ILT

Performance and Results Annual Report 2006

Annual Report Fraunhofer Institute for Laser Technology ILT 2006 Foreword

manufacturing techniques that we will The Fraunhofer ILT has actively accom- be able to hold onto or even expand panied its implementation from the our top-league position as an export very start. The initiative has already nation and justify our claim to being produced its first results: the signing-up the Land of Ideas. It is the only way to of over 500 members, the submission generate growth and create jobs for of a European agenda to EU commis- the future. And this implies that govern- sioner Viviane Reding, and the creation ment and industry must demonstrate of a new unit dedicated to optical tech- an even greater commitment than in nologies by the European Commission. the past, both ideologically and finan- Total funding of 90 million euros has cially, to research and education. been earmarked for photonics projects in 2007 and 2008 under the 7th Frame- »Germany - Land of Ideas« is the title The German government has followed work Programme. of an initiative under the patronage this call to action by making available of German president Horst Köhler, around 15 billion euros between now The Fraunhofer ILT intends to strengthen launched in 2006, the year in which and 2009 under its high-tech strategy its focus on nanophotonics, microen- the country was hosting the FIFA World to promote innovation. More specifi- gineering and surface engineering in Cup, as a means of illustrating to the cally, 310 million euros have been set the coming years. The Institute has ob- world how innovative and creative Ger- aside for projects in the field of optical tained certification for a number of many can be. The Fraunhofer Institute technologies, and 250 million euros for applications used in the aircraft industry for Laser Technology was among the production technologies. Such support for the repair of engine components. 365 »landmarks« selected to represent gives us the motivation to continue There is still considerable potential for the Land of Ideas. This was not the first working on promising innovations with new polishing, structuring, and gene- social marketing campaign launched in our partners. In the field of nano-pho- ration techniques. Advances in laser- an effort to make the German people tonics, EUV technology is one of the assisted microfabrication processes are more aware of their strengths and major thematic areas that the Fraun- being driven by innovative sectors of encourage them to take up the chal- hofer ILT has been driving forward for industry including medical devices, lenge of designing their own future. many years. Over the next few months, mechatronics, and solar technology. An earlier campaign in 2005, pro- our industrial partner will be testing A foretaste of things to come was pro- claiming »You are Germany«, carried the first alpha version of the tools we vided by the Aachen Colloquium for a similar message. The all-important have designed for an industrial EUV Laser Technology AKL’06 held on May question we must ask ourselves, how- lithography plant for semiconductor 3 to 5, 2006. Over 430 participants ever, is how best to channel all that manufacturing, with a view to their gathered to hear about the latest creative energy into preserving and future implementation in a full-scale developments in laser technology for improving our standard of living, given production environment. Interesting the production environment and dis- that the world around us is developing things are also happening in the field cuss its future prospects. The response at such a tremendous pace. of laser beam sources. Fiber technology, was so positive that we will be inviting tunable lasers, high-quality fiber-coupled the laser community to meet in Aachen One of the key aspects with regard diode lasers, are all areas of research once again in 2008, on May 7 to 9. to the global market is no doubt the in which the Fraunhofer ILT is heavily We can promise you a highly interest- competitive status of our manufactur- involved. ing program and a chance to do some ing industry and the service sector that efficient business networking. All that relies on its vitality. Because ours is a Now that the European Commission’s remains is for me to wish you every high-wage country, we have to con- 7th Framework Programme is under success with your development projects. centrate our strengths on producing way, the conditions are right for pur- premium-quality goods, with a special suing urgently needed pre-competitive Sincerely, focus on those products that can be research on a transnational scale in the manufactured using a high level of au- context of collaborative projects. The tomation. The key to this is innovation. technology platform »Photonics 21« For it is only by designing innovative serves as a communication network for products and employing automated interested companies and institutes. Professor Reinhart Poprawe M.A.

Fraunhofer ILT Annual Report 2006 3

Contents

Profile of the Institute 6 Some Special Research Results from the Business Areas Declaration of Principles 7 of Fraunhofer ILT

Business Areas 8 Laser and Plasma Sources 33 - 58

Board and Committees 10 Laser Material Processing 59 - 100

Contacts 11 Laser Plant and System Technology 101 - 110 Core Areas 12 Laser Measurement Services 14 and Testing Technology 111 - 132

Facts and Figures 16 European Laser Institute ELI 110

References 19 Patents 133

Fraunhofer USA Center Dissertations 134 for Laser Technology CLT 20 Diploma Theses 134 Coopération Laser Franco-Allemande CLFA 22 Scientific Publications 135

Fraunhofer Alliance Surface Lectures 137 Engineering and Photonics VOP 24 Conventions and Conferences 141 The Fraunhofer-Gesellschaft at a Glance 26 Trade Fairs 145

Laser Technology Publications 146 at RWTH Aachen 28 Technical Book »Laser Cluster of Excellence Technology for Manufacturing« 149 »Integrative Production Technology for High-Wage Countries« 30 Video Films and Multimedia Software 150 PhotonAix e. V. - Competence Network for Optical Technologies 32 Information Service 152

Imprint 153

Fraunhofer ILT Annual Report 2006 5 Profile of the Institute

In the business area »laser plant and Short Profile system technology« prototypes are developed, built up and installed on site. ILT - for more than twenty years, this ab- Process monitoring and control as well breviation has stood for extensive know- as system components and control how in laser technology. Innovative software are part of the activities. In solutions for manufacturing and pro- the business area »laser measurement duction problems, development of and testing technology« processes and new technical components, competent systems for inspection of surfaces, for DQS certified by advice and training, highly-qualified chemical analysis, for testing the accu- DIN EN ISO 9001 personnel, the latest technologies and racy of dimensions and geometry of Reg.-No.: DE-69572-01 an international reputation: these are workpieces as well as for analysis of the guarantors for long-term business static and dynamic deformations are relations. The numerous customers of developed. the Fraunhofer Institute for Laser Tech- nology ILT belong to various sectors The comprehensive offer of services like automobile industry, mechanical of the Fraunhofer Institute for Laser engineering, chemical and electrical Technology ranges from research and engineering, steel construction, preci- development as well as system construc- sion mechanics and optics. tion and quality assurance to advice and training. Industrial laser systems With more than 250 employees and from various manufacturers as well as 10.000 m2 of usable floor space the an extensive infrastructure are available Fraunhofer Institute for Laser Technolo- for the work on research and gy is world-wide one of the most development projects. important development and contract research institutes of its specific field. In the Laser User Center of the Fraun- The four business areas cover a wide hofer Institute for Laser Technology range of actual and vertical integrated guest companies work in their own topics. In the business area »laser and separated laboratories and offices. The plasma sources« development activities basis of this special form of technology are concentrated on innovative diode transfer is a long-term cooperation and solid state lasers for industrial use agreement with the institute in the as well as compact EUV-sources for field of research and development. lithographic use in semiconductor The surplus value lies in the use of the production. The business area »laser technical infrastructure and in the material processing« offers solutions information exchange with ILT´s in cutting, ablation, drilling, welding, experts. Already 10 companies profit soldering, surface treatment and micro from the advantages of the Laser User processing. The activities cover a wide Center. Besides laser manufacturers range of applications from macro and laser users, entrepreneurs from processing via nano structuring to the areas of special machine production, biophotonics. laser processing and laser measurement find a suitable frame to realize their ideas on an industrial scale.

6 Fraunhofer ILT Annual Report 2006 Declaration of Principles

Mission

We occupy an international top position in transferring laser technology to industrial application.

We continually expand the knowledge base and know-how in our sector and make significant contributions to the ongoing development of science and technology.

Working with our partners in industry, science and government, we create innovations on the basis of new beam sources and new applications.

Customers

The customers needs are the focus of our work.

Discretion, fairness and a spirit of part- Fascination: Laser Management style nership are top priorities in our customer relationships. Our customers can rely The unique characteristics of laser light Cooperative, demanding and suppor- on us. and the resulting diversity of applica- tive. Knowing the value of our staff as tions, are a constant source of inspiration individuals and the value of their We tailor solutions and their cost- and fascination. know-how and their commitment effective implementation to the forms the basis of our management demands and expectations of our philosophy. We involve our staff in the customers, with the objective of formulation of goals and the decision- creating a competitive advantage. Staff making process. We place a high value on effective communication, goal- We support industry’s needs for new Teamwork between the individual oriented and efficient work and clear specialists and managerial staff and the group is the foundation of our decisions. through project-based partnerships success. with our customers.

We want our customers to be satisfied Position - because we want them to return. Strengths We work within vertical structures, Our broad spectrum of resources from research to application. enables us to offer one-stop solutions. Chances Our expertise extends from beam source, machining and measuring techniques, We strategically expand our knowledge to application, through to integration base across the network. of systems into the customer’s produc- tion line.

Fraunhofer ILT Annual Report 2006 7 Business Areas

Laser and Plasma Sources Laser Material Processing

This business area encompasses the Production processes addressed by development of diode laser modules this business area include cutting and and systems as well as diode-pumped joining techniques applying micro- and solid-state lasers with different reso- macro-technology, as well as surface nator structures (stab,slab,fiber), the engineering. The services provided design of new diode laser structures, extend from process development for the microassembly of diode lasers and the manufacture of sector-specific optical components, and the develop- products and the integration of these ment of plasma systems. processes in production lines, through simulation services for laser applications, For more than 10 years spinn-offs of to the production of samples in sup- the Fraunhofer ILT are set up in the port of series production start-up. The framework of some projects. In coope- strength of the business area is rooted ration with the Fraunhofer IAF new in its extensive process know-how, structures are being designed which which is tailored to specific customer permit the manufacture of diode lasers requirements in each case. In addition demonstrating higher beam quality. to process development, the business The business area continues to enjoy area offers complete system solutions a unique reputation in the assembly which utilize selected technology net- of high-power diode lasers and in works. Customers are offered laser- particular the installation of automated specific solutions that encompass design assembly and test facilities. Work in engineering, material specification, the plasma technology sphere focuses product design, production equipment on the development of EUV beam and quality assurance. In addition to sources for semiconductor lithography. the target market of material process- The main target markets for the busi- ing, the business area also addresses ness area as a whole are laser machining, customers in the medical engineering, medical engineering and metrology, biotechnology and chemical sectors. along with the component market for information and communications tech- nology.

8 Fraunhofer ILT Annual Report 2006 Business Areas

Laser Plant and Laser Measurement System Technology and Testing Technology

This business area focuses on the deve- The services provided by this business lopment of prototype equipment for area include the development of mea- laser and plasma-technology applica- surement and testing processes and tions, as well as on laser systems related equipment for material analysis engineering, particularly in the fields and for geometric testing and surface of automation and quality assurance. inspection. The requisite measurement Areas of application embrace welding, and testing software is tailored to cutting, hardening, repair coating, customer-specific problem areas. Material drilling and micro-joining. The system analysis is based on the deployment of technology offered provides complete laser-spectroscopic processes, focusing solutions for process monitoring, com- on the analysis of metallic and oxidic ponents and control systems for preci- materials, identification testing of high- sion machining, laser-specific CAD/CAM alloy steels, rapid recognition of mate- technology modules, as well as soft- rials for recycling tasks and analysis of ware for measurement, open- and gases and dust. Special electronic com- closed-loop control and testing. For ponents are developed for the parallel its work in process monitoring in parti- processing of detector signals of high cular the business area can draw on bandwidth. extensive and, where required, patent- protected know-how. In this sector In biophotonics joint projects are car- numerous systems have already been ried out in the field of highly sensitive licensed for companies. Target markets fluorecence detection for protein chips include laser equipment and compo- and laser scattered light measurements nent manufacture as well as all sectors in sub-µl test volumes for protein of production industry which deploy crystallization. As part of the area’s lasers in their manufacturing activity work on geometric testing and surface or intend to do so. inspection components, devices and equipment are being developed for obtaining 1 to 3D information about the geometry or surface properties of workpieces. These include processes and special systems for testing the stability of bar and strip products and devices for the 1D to 3D scanning of unit goods. Target markets include the production and the recycling industry which conduct measurement and testing fast and close to the process.

Fraunhofer ILT Annual Report 2006 9 Board and Committees

Dr. Ulrich Steger Board Ministerium für Innovation, Science & Technology Council Wissenschaft, Forschung The Board of Trustees advises the und Technologie des Landes NRW The Fraunhofer-Gesellschaft’s Science Fraunhofer-Gesellschaft as well as the & Technology Council supports and Institute’s management and supports Dr. Dieter Steegmüller advises the various bodies of the the links between interest groups and DaimlerChrysler AG Fraunhofer-Gesellschaft on scientific the research activities at the institute. and technical issues. The members The Board of Trustees during the year Dr. Klaus Wallmeroth are the institutes’directors and one under review consisted of: TRUMPF Laser GmbH & Co. KG representative elected from the science/ technology staff per institute. C. Baasel (Vorsitzender) The 22nd Board of Trustees meeting Carl Baasel Lasertechnik GmbH was held on September 20, 2006 Members of the Council from the ILT at the Fraunhofer ILT in Aachen. are: Prof. Dr. R. Poprawe, B. Theisen, Dr. R. G. Gossink Dr. C. Janzen. Philips Forschungslabor GmbH

H.-J. Haepp Directors’ Committee DaimlerChrysler AG Department of Laser Technology LLT The Directors’ Committee advises the at the RWTH Aachen Dr. Ulrich Hefter Institute’s managers and is involved Rofin-Sinar Laser GmbH in deciding on research and business The Fraunhofer ILT is home to most of policy. The members of this committee the Department of Laser Technology. Dipl.-Ing. H. Hornig are: Vasvija Alagic, Dipl.-Phys. This means that a close scientific relation- BMW AG A. Bauer, Dr. K. Boucke, Dr. A. Gillner, ship between the Fraunhofer ILT and Dr. J. Gottmann, Dipl.-Ing. H. D. Hoff- the Department of Laser Technology Dr. U. Jaroni mann, Dr. S. Kaierle, Dr. I. Kelbassa has been built up, based on a contract ThyssenKrupp Stahl AG (since Aug. 2006), Dr. E.-W. Kreutz, of cooperation. Prof. Dr. rer. nat. Prof. Dr. P. Loosen, Dr. W. Neff, Dr. R. Reinhart Poprawe M.A. is Director of Prof. Dr. G. Marowsky Noll, Dr. D. Petring, Prof. Dr. R. Poprawe, the Department of Laser Technology, Laserlaboratorium Göttingen e. V. Prof. Dr. W. Schulz, B. Theisen, Dr. Ingomar Kelbassa is Academic Dr. B. Weikl, Dr. K. Wissenbach. Director z. A.. MinRat Dipl.-Phys. T. Monsau Ministerium für Arbeit und Soziales, Qualifikation und Technologie des Landes NRW Health & Safety Committee Betriebsrat

Dr. Rüdiger Müller The Health & Safety Committee is In March 2003 the staff association Osram Opto Semiconductors responsible for all aspects of safety was elected by the employees of the GmbH & Co. OHG and laser safety at the Fraunhofer ILT. Fraunhofer ILT and the Department Members of this committee are: of Laser Technology. Members are: Dr. Joseph Pankert Vasvija Alagic, K. Bongard, M. Brankers, Dipl.-Ing. P. Abels, Dipl.-Ing. G. Backes, Philips Lighting B.V. A. Hilgers, Dr. E.-W. Kreutz, A. Lennertz, M. Brankers, Dipl.-Phys. J. Geiger, Dr. W. Neff, E. Neuroth, Dipl.-Ing M. Janßen, Dipl.-Phys. G. Otto, Prof. R. Salathé M. Poggel, Prof. Dr. R. Poprawe, B. Theisen (chair), Dr. A. Weisheit, Ecole Polytechnique Fédéral B. Theisen, Dipl.-Ing. F. Voigt, Dipl.-Ing. Dipl.-Ing. N. Wolf. de Lausanne N. Wolf, Dr. R. Keul (Berufsgenossen- schaftlicher Arbeitsmedizinischer Dienst MinR Dr. Frank Schlie-Roosen BAD). Bundesministerium für Bildung und Forschung BMBF

10 Fraunhofer ILT Annual Report 2006 Contacts

Prof. Dr. Reinhart Poprawe (-110) Prof. Dr. Peter Loosen (-162) Dr. Dirk Petring (-210) Director Vice Director Cutting and Joining

Dipl.-Phys. Axel Bauer (-194) Dr. Konstantin Boucke (-132) Dr. Konrad Wissenbach (-147) Marketing and Communication Laser Components Surface Treatment

Vasvija Alagic (-181) Dipl.-Ing. Dieter Hoffmann (-206) Dr. Arnold Gillner (-148) Administration Solid State and Diode Lasers Micro Technology

Dr. Bruno Weikl (-134) Dr. Reinhard Noll (-138) Dr. Stefan Kaierle (-212) IT-Management Laser Measurement and System Technology Testing Technology

Dr. Alexander Drenker (-223) Dr. Willi Neff (-142) Prof. Dr. W. Schulz (-204) Quality Management Plasma Technology Modelling and Simulation

Fraunhofer ILT Annual Report 2006 11 Core Areas

Laser Components Laser Measurement and Testing Cutting and Joining Dr. Konstantin Boucke Technology Dr. Dirk Petring Dr. Reinhard Noll • Active und passive cooling • Cutting, perforating, drilling, of diode lasers • Laser measurement processes deep-engraving • Expansion-matched coolers and for online inspection tasks • Welding, brazing, soldering mounting technologies for laser • Development, construction, • High-speed processing diode bars integration and testing of laser • Thick section processing • Mounting of laser diode bars measurement and testing equipment • Cutting and joining of special with indium- and AuSn solder • Chemical analysis of solid, liquid materials • Characterization and testing and gaseous substances with laser • Welding with filler material of diode lasers in the wavelength spectroscopy • Laser-arc hybrid technologies regime between 630 nm and • Spectroscopic monitoring • Product-oriented process 2.1 µm of welding processes optimization • Design and assembly • Fluorescence analysis • Multi-functional manufacturing of micro-optical systems • Quantification of protein processes • Fiber coupling for singlemode interactions using label-free laser • Design and implementation and multimode fibers scattering methods of processing heads • Automation of high-precision • In vivo diagnostics for online mo- • Sensor-based process control assembly processes for lasers nitoring of minimal invasive surgery • Computer-supported simulation and optical systems • Measurement of distances, profiles and optimization and shapes with laser triangulation • Multimedia training and information • Real time operation and automation systems

Solid State and Diode Lasers Plasma Technology Surface Treatment Dipl.-Ing. Dieter Hoffmann Dr. Willi Neff Dr. Konrad Wissenbach

• Development of solid state • Development of plasma based • Transformation hardening, remelting, and diode lasers EUV/XUV-sources cladding, alloying and dispersing • Development of fiber lasers • Development, construction and for the production of load orientated • Methods and components integration of components for layers for frequency doubling EUV/XUV-measuring systems • Development of powder feeding • Optical design for lasers, beam guid- (microscopy, surface characterization, systems ing and forming of laser radiation measurement of reflectivity …) • Heat treatment of coated and • Development of diode laser modules • Power generators for pulsed uncoated surfaces and systems plasma formation • Functionalising of nano-particulate • Design and characterization • Process control and monitoring coatings of optical components systems for spatially arranged • Cleaning and modification of surfaces • Development of components systems based on micro seconds such as burr removing, activation and for solid state and diode lasers • Atmospheric pressure plasma for structuring surface modification (sterilization • Rapid prototyping und rapid of packaging material, functiona- manufacturing for production lization …) of metallic parts and tools • Polishing of metals and glass

12 Fraunhofer ILT Annual Report 2006 Core Areas

Micro Technology Modelling and Simulation System Technology Dr. Arnold Gillner Prof. Dr. W. Schulz Dr. Stefan Kaierle

• Laser micro soldering and • Generation of EUV-radiation • Process monitoring and control micro welding • Design of optical resonators for quality assurance • Laser supported adjustment for high power diode lasers • Process analysis and process • Laser assisted deep drawing • Beam guiding, beam shaping development tools and punching • Flow and heat transport in gases • Development of online sensors and • Micro tool technology and melt control systems (e. g. seam tracking, • Precision cutting and drilling • Movement of phase boundaries velocity measurement, positioning, of metals, ceramics, semiconductors • Dynamical models of removing, distance measurement and control, and diamonds cutting, welding and drilling multi-sensor technology and net- • Micro structuring with excimer, • Evaluation and visualization of data works) Nd:YAG- and short pulse lasers from measurement and simulation • Automated testing of processing • Marking and lettering • Computational steering of results (e. g. systems for seam • Cutting and perforating of paper, simulations evaluation) plastics and composite materials • Numerical methods and codes, • Process trials and testing • Welding of thermoplasts and finite elements and finite volumes • Feasibility studies thermoplastic elastomeres in domains with free boundaries, • Pilot-run series • Laser medicine adaptive cross linking • Integration of laser technology into • Biophotonics • Diagnostics of laser radiation and existing production facilities • Photochemical processes laser manufacturing processes • Remote and scanner applications • Nano structuring with laser • Integrated processing heads radiation • CAD/CAM-supported laser • Laser modification for bio processing functional surfaces • Offline path planning and simulation • Micro manipulation of cells • Conception and design of plants with laser radiation • Pilot plants • Control techniques for laser plants • Consulting, education and training

Fraunhofer ILT Annual Report 2006 13 Services

Services Cooperations with R&D-Partners

The services of the Fraunhofer Institute The Fraunhofer Institute for Laser for Laser Technology ILT are continually Technology ILT is cooperating with being adapted to the practical require- R&D-partners in different ways: ments of industry and include the • Realization of bilateral, company solution of manufacturing problems specific R&D-projects with and as well as the realization of test series. without public support In detail this means: (contract for work and services) • development of laser beam sources • participation of companies in • manufacturing and assembling public-funded cooperative projects technology (cofinancing contract) • pulsed power supplies and control • Production of test, pilot and technology prototype series by Fraunhofer ILT • beam guiding and forming to determine the reliability of • development, set-up and testing the process and minimize the of pilot plants starting risk • process development (contract for work and services) • process monitoring and control • companies with guest status at • model and test series Fraunhofer ILT • integration of laser technology into (special cooperation contracts) already existing production plants • X-ray and plasma systems By means of cooperation with other research organizations and specialized companies the Fraunhofer Institute for Laser Technology offers solutions even in the case of interdisciplinary tasks. A special advantage hereby consists in the direct access to the large resources of the Fraunhofer Society.

During the implementation phase of new laser processes and products, companies can acquire ‘guest status’ at the Fraunhofer Institute for Laser Technology and use the equipment, infrastructure and know-how of the institute as well as install their own systems.

14 Fraunhofer ILT Annual Report 2006 Services

• sensors for process control in laser Facilities material processing Fraunhofer ILT abroad • direct-writing and laser-PVD stations The usable floor space at the Fraun- • clean rooms for assembly of diode Since its foundation, Fraunhofer ILT hofer Institute for Laser Technology ILT lasers, diode laser systems and has been involved in many international amounts to more than 10,000 m2. diode pumped solid state lasers cooperations. The objective of these • live sience laboratory with S1 and cooperations is to recognize new Technical Infrastructure S2 classification trends and current developments and The technical infrastructure of the • devices for process diagnostics and to acquire further know-how. The institute includes a mechanical and high speed video analysis customers of Fraunhofer ILT can directly electronic workshop, a metallurgic • laser spectroscopic systems for the benefit from this. Fraunhofer ILT carries laboratory, a photographic laboratory, chemical analysis of solid, liquid and out bilateral projects as well as interna- a laboratory for optical metrology as gaseous materials tional cooperative projects with foreign well as a department for design and • laser triangulation sensors for companies and subsidiaries of German construction. The Fraunhofer ILT also distance and contour measurement companies abroad. These companies has a video conference room and a • laser coordinate measuring machine can also contact Fraunhofer ILT computer network. • confocal laser scanning microscopy through: • international subsidiaries of Scientific Infrastructure Fraunhofer ILT The scientific infrastructure includes • foreign cooperation partners of a library with international literature, Fraunhofer ILT patent and literature data bases as • liaison offices of the Fraunhofer well as programmes for calculation Society abroad of scientific problems and data bases for process documentation.

Equipment The equipment of the Fraunhofer Institute for Laser Technology ILT is permanently being adapted to the state-of-the-art. At present, essential components are:

• CO2-lasers up to 20 kW • lamps and diode pumped solid © AVIA-Luftbild, Aachen state lasers up to 8 kw Dipl.-Ing. Martin Jochum • fiber lasers, up to 4 kW • diode laser systems up to 3 kW • SLAB laser • excimer lasers • ultra short pulse laser • broardband tunable laser • five-axis gantry systems • three-axis processing stations • beam guiding systems • robot systems

Fraunhofer ILT Annual Report 2006 15 Facts and Figures

Employees

Employees at the Fraunhofer ILT 2006 number

Personnel 137 - Scientists and engineers 84 - Technical staff 33 - Administrative staff 20 Other employees 128 - Undergraduate assistants 119 - External employees 7 - Trainees 2 Total number of employees at the Fraunhofer ILT 265

• 6 members of staff completed their doctorates • 26 undergraduates carried out their final year projects at the Fraunhofer ILT

Employees 2006

45 % Undergraduate assistants

8 % Administrative staff

12% Technical staff

3 % External employees, trainees • 6 Mitarbeiter haben ihre Promotion abgeschlossen 32 % Scientists/engineers • 26 Studenten haben ihre Diplomarbeit am Fraunhofer ILT durchgeführt

16 Fraunhofer ILT Annual Report 2006 Facts and Figures

Revenues and Expenses

Expenses 2006 Mill. EUR

- Staff costs 9,0 - Material costs 9,0 Expenses operating budget 18,0

Investments 2,7

Revenues 2006 Mill. EUR

- Industrial revenues 7,0 - Additional financing from Federal Government, States and the EU 6,1 - Basic financing from the Fraunhofer-Gesellschaft 4,9 Revenues operating budget 18,0 - Revenues from projects abroad (already included in total) 3,3

Investment revenues from industry 0,3

Fraunhofer industry ρInd 41 %

Expenses 2006 (100 %) Revenues 2006 (100 %)

43,5 % Material costs 34 % Additional financing from Federal Government, States and EU

13 % Investments 27 % Industrial revenues

43,5 % Staff costs 39 % Basic financing from the Fraunhofer-Gesellschaft

Fraunhofer ILT Annual Report 2006 17 Facts and Figures

Budget Growth

The following graph illustrates the budget trend over the last 7 years.

Project revenues - public funding Project revenues - industrial funding Basic financing by Fraunhofer

18,6 18,0 17,5 17,1 17,4 16,4

14,8

18 Fraunhofer ILT Annual Report 2006 References

March 2007 Printed with the kind permission of our partners.

The companies listed here represent a selection of the Fraunhofer ILT’s many clients. Fraunhofer USA Center for Laser Technology CLT

The American partners’ interest Short Profile concentrates on: • Using the competence of the The Fraunhofer Center for Laser Tech- Fraunhofer Institutes for American nology CLT, located in Plymouth, companies Michigan, has a 1250 m2 development • Using the experience in the center housing $9 million worth of the introduction of new technologies most varied, leading edge laser equip- • Providing the connection between ment in North America. This area has industry and university established itself as the center for laser • Providing practical training for production, system integration and students and graduate students industrial users in the USA. In cooperation with the University of Michigan fiber lasers are developed. The on-going goals are: Basic technology and new concepts for • Integration in scientific and components and fibers emerge at the industrial development in the USA university. Fraunhofer undertakes the • Growth in know-how by faster development of suitable pump sour- recognition of trends in the field of ces, system integration and prototype laser and production technology building. The focus of the investigation • Accelerated use of R&D and work is on diffraction limited radiation, fle- methods, in which the USA is the xible pulse characteristic and monolithic leader construction, as well as systems with • Know-how growth through close kW-output power are deployed inten- cooperation with the Wayne State sively. University and the University of Michigan. In collaboration with the Wayne State • Strengthening position in the University, durably stable implants for R&D market neurostimulation of the human brain • Increase of industrial return from are being developed. The CLT is also the USA the main sponsor of the »Laserspot« • Increase of motivation and organization, founded in 2000, and qualification level of employees meanwhile supported by over 20 members. The purpose of Laserspot is The central philosophy of Fraunhofer to promote applications of laser tech- USA is the creation of a German- nology in various branches of industry. American joint venture where give and take occur in harmony. The win-win Due to rapid commercialization of situation is an essential prerequisite research results and common process- for both sides. The Fraunhofer ing of research results, Visotek was Gesellschaft is always interested in established out of the CLT in 2001. considering and trying to develop Visotek produces intelligent laser tools relationships on the American side and runs job order production for the that strengthen mutually. automobile industry. Fiber coupled diode lasers with kilowatt output power were successfully transferred from the research into the market. A further common development is a special optic, which enables rapid two dimensional scanning and auto focus for lasers with an output power up to

20 Fraunhofer ILT Annual Report 2006 Fraunhofer USA Center for Laser Technology CLT

15 kW. This optic was successfully applied in the shipbuilding for welding Equipment Contact of thick plates with variable weld seam width and in the automotive industry Current equipment in the CLT lab con- for robotic remote welding. Visotek sists of: CO2 lasers with up to 8 kW can perform 250 welding spots per power, Nd:YAG laser from 250 W to minute with 6 kW laser power. 4.4 kW, diode lasers from 30 W to 3 kW, frequency trebled Nd:YAG laser and excimer laser, a number of special and hybrid optics, a series of 3, 5 and Services 6 axes systems, as well as several Dr. Stefan Heinemann robots. Director The CLT offers services in the field of laser processing, the development 46025 Port Street of optical components and special Plymouth laser systems. This covers the entire References Michigan 48170 spectrum from feasibility studies, USA process development to pre-series • US Air Force Research Laboratories development as well as prototype • Office of Naval Research Telefon: +1 734 / 354 -6300 production of laser beam sources and • Michigan Lifescience Corridor Extension: -210 laser systems which are ready to use. • Alcan Fax: +1 734 / 354 -3335 As an independent institution small • Borg Warner Automotive and mid-sized companies are given the • Dana Corporation [email protected] opportunity to develop and test their • DaimlerChrysler www.clt.fraunhofer.com processes on Fraunhofer machines • Ford Motor Company with the help of Fraunhofer personnel. • General Motors It is also possible to develop and test • Hemlock Semiconductors complete systems at the CLT. Our • Nuvonyx customers come from the automobile • LASAG industry, construction industry, ship • PRC building and medical engineering. • Rofin Sinar • Spectra Physics • Siemens VDO • Trumpf Employees • Visteon

Both Germans and Americans are employed at the CLT. The goal is to rotate German employees so that the Operating Budget 2006* collected experience can be brought over to the parent institutes and to Mio. US$ offer German employees the opportu- nity to become further qualified during Operating budget 2.35 their stay in the USA. Furthermore, - Staff costs 1.15 students from the Technical University - Material costs 1.20 in Aachen write their diploma thesis *Post-calculation has not occurred yet in the USA.

Fraunhofer ILT Annual Report 2006 21 Coopération Laser Franco-Allemande CLFA

The CLFA is actively participating in the Short Profile realization of European research and is a result of increasing link of application At the CLFA in Paris, the Fraunhofer oriented research and development in Institute for Laser Technology ILT has the field of laser technology in Europe. been cooperating since 1997 with The cooperation of the Fraunhofer ILT leading French research organizations, with the French partners contributes including ARMINES, the École Nationale to the improvement of the presence of Supérieure des Mines de Paris ENSMP, the Fraunhofer Gesellschaft in Europe the Institut de Soudure, the Institut with the advantages for the French Universitaire de Technologie du Creusot, and German sides equally taken into the École Nationale Supérieure de consideration. On an international scale Mécanique et des Microtechniques this cooperation further strengthens the ENSMM in Besançon and other major leading position of European industry laser application centers in France. in the laser supported manufacturing Multidisciplinary teams of specialists process. from Germany and France work to- gether on the transfer of laserassisted The French partners’ interests concen- manufacturing processes to European trate on: industry. The Coopération Laser Franco- • Using the competence of the Allemande is a member of the Club Fraunhofer ILT for French companies Laser et Procédés, the French association • Using the experience of the Fraun- of laser manufacturers and users. hofer ILT in the introduction of new technologies The on-going goals of the CLFA are: • Providing the connection between • Integration into scientific and industry and university with practical industrial development in France training for students and graduate • Growth in know-how by faster students recognition of trends in the fields of European laser and production technology • Strengthening the position in the R&D market • Assembly of a European competence center for laser technology • Increase of mobility and qualification level of employees

Visit of the French research minister François Goulard at the »Fête de la Science« from October 9 bis 15, 2006 in Paris.

22 Fraunhofer ILT Annual Report 2006 Coopération Laser Franco-Allemande CLFA

Services Equipment Contact

The CLFA offers services in the field of In addition to the technical resources laser material processing. This covers available at the Fraunhofer ILT in the entire spectrum from application Germany, the CLFA possesses its oriented fundamental research and own infrastructure at the Centre des training, feasibility studies and process Matériaux Pierre-Marie Fourt, an out- development to pre-series development station of the Ecole des Mines de Paris and system integration. Small and mid- based in Evry, south of Paris. Facilities sized companies have the opportunity include access to the center’s material Dr. Wolfgang Knapp here to get to know and test laser analysis laboratories. The technical Director technology in an independent system. infrastructure of other French partners The open development platform allows can also be shared on a project- or CLFA c/o Armines the French customers to test and qua- customer-specific basis. 60 Boulevard Saint Michel lify new laser supported manufacturing 75272 PARIS Cedex 6 processes. France

Locations Telephone: +33 1 / 4051 -9476 Fax: +33 1/4634-2305 Employees Paris - at the École Nationale Supérieure des Mines de Paris ENSMP, in central [email protected] At the CLFA employees from France Paris. www.ilt.fraunhofer.de/clfa.html and Germany work together. A mutual exchange of personnel occurs between Evry - on the premises of the Centre Aachen and Paris for joint projects. des Matériaux Pierre-Marie Fourt, The employees therefore have the roughly 40 km south of Paris. opportunity to improve their compe- tence especially with regard to mobility and international project management.

Fraunhofer ILT Annual Report 2006 23 Fraunhofer Alliance Surface Engineering and Photonics VOP

Competence by Networking Fraunhofer Institute for Physical Measurement Techniques IPM Six Fraunhofer Institutes cooperate in the Network Surface Engineering and The Fraunhofer IPM develops optical Photonics VOP. Complementary com- systems for applications in spectros- petencies allow to adapt the research copy and light exposure technology. activities to the rapid technological A major focus is the realisation of highly progress in all industrial application dynamical systems. Besides a rapid fields in a permanent, apace and flexible activation, they require special compe- way. Co-ordinated strategies, in line tencies in signal processing as realised with the currents needs of the market, through robust and lowmaintenance create synergy effects and provide measurement systems for the infra- a larger service for the benefit of the structure monitoring of highspeed roads. customers.

Fraunhofer Institute for Fraunhofer Institute for Electron Laser Technology ILT Beam and Plasma Technology FEP In the area of laser technology, the The ambition of FEP is the research interactive relationship between laser and development of innovative development and laser applications is processes for the utilisation of high of prime importance. New lasers allow performance electron beams and new applications, and new applications vacuum sealed plasmas for surface set the stage for new laser systems. technology. Priority is given to problems This is why the Fraunhofer ILT is conti- like process monitoring, quality control, nually expanding its core competencies reproducibility, scaling, and profitability. through close cooperation with leading laser manufacturers and innovative laser consumers.

Above: Fraunhofer FEP Middle: Fraunhofer IPM Below: Fraunhofer ILT

24 Fraunhofer ILT Annual Report 2006 Fraunhofer Network Surface Engineering and Photonics VOP

Fraunhofer Institute for Surface Fraunhofer Institute for Material Engineering and Thin Films IST and Beam Technology IWS

As an industry oriented R&D service The Fraunhofer IWS is conducting centre, the Fraunhofer Institute for research in the areas of laser techno- Surface Engineering and Thin Films IST logy (e.g. laser beam welding, cutting, is pooling competencies in the areas hardening), surface technology (e.g. film deposition, coating application build-up welding), micro machining as and film characterization. Presently, the well as thin film and nano technology. institute is operating in the following The integration of material testing and business fields: mechanical and auto- characterisation into research and motive engineering; tools; energy; development constitutes and upgrades glass and facade; optics; information the IWS spectrum. and communication; life science and ecology.

Contact und Coordination

Fraunhofer Institute for Applied Speaker of the Network Optics and Precision Engineering IOF Prof. Dr. Eckhard Beyer

The core of the research activity of Coordination Fraunhofer IOF is optical systems Udo Klotzbach engineering aimed at a steady improve- Telephone: ++49 (0)351 / 2583252 ment of light control. The institute's [email protected] focus is on multifunctional optical www.vop.fraunhofer.de coatings, optical measurement systems, micro-optical systems, systems for the The Institutes characterisation of optics and compo- www.fep.fraunhofer.de nents for precision mechanics assem- www.ipm.fraunhofer.de blies and systems. www.ilt.fraunhofer.de www.ist.fraunhofer.de www.iof.fraunhofer.de IST www.iws.fraunhofer.de

FEP ILT

Above: Fraunhofer IST IWS Middle: Fraunhofer IOF Below: Fraunhofer IWS

IOF

IPM

Fraunhofer ILT Annual Report 2006 25 The Fraunhofer-Gesellschaft at a Glance

At present, the Fraunhofer-Gesellschaft • Process engineering The Fraunhofer-Gesellschaft maintains more than 80 research units, • Energy and construction including 56 Fraunhofer Institutes, at engineering, environmental and Research of practical utility lies at the 40 different locations in Germany. The health research heart of all activities pursued by the majority of the 12,500 staff are quali- • Technical/economic studies, Fraunhofer-Gesellschaft. Founded in fied scientists and engineers, who work information transfer 1949, the research organization under- with an annual research budget of EUR takes applied research that drives eco- 1.2 billion. Of this sum, more than EUR nomic development and serves the 1 billion is generated through contract wider benefit of society. Its services are research. Two thirds of the Fraunhofer- Target Groups solicited by customers and contractual Gesellschaft’s contract research revenue partners in industry, the service sector is derived from contracts with industry The Fraunhofer-Gesellschaft is commit- and public administration. The orga- and from publicly financed research ted to working for the economy as a nization also accepts commissions from projects. Only one third is contributed whole, for individual businesses and German federal and Länder ministries by the German federal and Länder for society. The targets and benefi- and government departments to parti- governments in the form of institutional ciaries of our research activities are: cipate in future-oriented research pro- funding, enabling the institutes to • The Economy: Small, medium-sized jects with the aim of finding innovative work ahead on solutions to problems and large companies from industry solutions to issues concerning the in- that will not become acutely relevant and service sectors can all benefit dustrial economy and society in general. to industry and society until five or ten from contract research. The Fraun- years from now. hofer-Gesellschaft develops con- Applied research has a knock-on effect crete, practical and innovative that extends beyond the direct benefits Affiliated research centers and represen- solutions and furthers the application perceived by the customer: Through tative offices in Europe, the USA and of new technologies.The Fraun- their research and development work, Asia provide contact with the regions hofer-Gesellschaft is an important the Fraunhofer Institutes help to rein- of greatest importance to present and ‘supplier’ of innovative know-how force the competitive strength of the future scientific progress and economic to small and medium-sized com- economy in their local region, and development. panies (SMEs) not equipped with throughout Germany and Europe. They their own R&D department. do so by promoting innovation, accele- The Fraunhofer-Gesellschaft is a re- • Country and society: Strategic rating technological progress, improving cognized non-profit organization research projects are carried out at the acceptance of new technologies, which takes its name from Joseph von federal and state level, promoting and not least by disseminating their Fraunhofer (1787-1826), the illustrious key technologies or innovations in knowledge and helping to train the Munich researcher, inventor and fields of particular public interest, urgently needed future generation of entrepreneur. e.g. environmental protection, scientists and engineers. energy technologies and preven- tative health care. The Fraunhofer- As an employer, the Fraunhofer-Gesell- Gesellschaft also participates in schaft offers its staff the opportunity to Fields of Research technology programs initiated by develop the professional and personal the European Union. skills that will allow them to take up The Fraunhofer-Gesellschaft concentrates positions of responsibility within their on research in the following fields: institute, in other scientific domains, • Materials technology, component in industry and in society. Students behavior working at the Fraunhofer Institutes • Production and manufacturing have excellent prospects of starting and technology developing a career in industry by virtue • Information and communication of the practical training and experience technology they have acquired. • Microelectronics, microsystems engineering • Sensor systems, testing technology

26 Fraunhofer ILT Annual Report 2006 The Fraunhofer-Gesellschaft at a Glance

Range of Services The Advantages of Contract Research Facilities in Germany Research The Fraunhofer-Gesellschaft develops products and services to full maturity. Cooperation between all the Fraunho- We work closely with our clients to fer institutes means that our clients create individual solutions, combining have access to a large number of the efforts of several Fraunhofer insti- experts covering a wide range of com- tutes if necessary, in order to develop petencies. Thanks to common quality more complex system solutions. The standards and professional project services provided by the Fraunhofer- management, the Fraunhofer institutes Gesellschaft are: ensure that research projects achieve • Product optimization and results that can be relied on. Our insti- development through to prototype tutes are equipped with up-to-date manufacture laboratory technology, making them • Optimization and development attractive to companies of all sizes and of technologies and production from all industrial sectors. As a strong processes community, we can provide our part- • Support for the introduction of ners with reliability and economic new technologies via: benefits: the Fraunhofer-Gesellschaft - Testing in demonstration centers can bring the knowledge already using highly advanced equipment gained from cost-intensive preliminary - In-house training for the staff research into joint projects. involved - On-going support, also sub- sequent to the introduction of new processes and products • Assistance in assessing new technologies via: - Feasibility studies - Market analyses - Trend analyses - Life cycle analyses - Evaluation of cost-effectiveness • Supplementary services, e.g.: - Advice on funding, especially for SMEs - Testing services and quality validation

Fraunhofer ILT Annual Report 2006 27 Laser Technology at RWTH Aachen

Jointly shaping the future Chair for Laser Technology LLT

The RWTH Aachen University Chairs The department of laser technology at for Laser Technology LLT and the Tech- RWTH Aachen has been engaged in nology of Optical Systems TOS, along application-oriented research and with the study and research depart- development in the fields of micro, ment for the non-linear dynamics of thin film, surface and x-ray technology laser production methods NLD, repre- and in integrated optics since 1985. sent an outstanding cluster of exper- Laser beam sources with short pulse tise in the field of optical technologies. durations of between 10-13 and 10-3 This permits supercritical treatment of seconds are employed in the micro basic and application-related research structuring of materials by ablation topics. The close cooperation with the and modification. Applications include Fraunhofer Institute for Laser Technolo- the drilling of holes in metal for aero- gy ILT not only permits industrial con- space engineering and the processing tract research on the basis of sound of glass by changing the index of fundamental knowledge, but also pro- refraction. vides new stimuli for the advanced development of optical methods, com- Pulsed laser deposition is used to pro- ponents and systems. The synergy of duce thin coatings for wear protection, infrastructure and know-how is put to electronics, integrated optics and active use under a single roof. medical engineering applications. Coating with laser beams makes it This structure particularly benefits up- possible to produce complex multi- and-coming young scientists and engi- component materials with controlled neers. Knowledge of current industrial film structures. and scientific requirements in the opti- cal technologies flows directly into the Laser-beam deposition welding is used planning of the curriculum. Further- in wear and corrosion protection, more, undergraduates and postgradu- maintenance and the production of 3D ate students can put their theoretical components. The chief customers are knowledge into practice through pro- mechanical engineering, tool manufac- ject work at the Fraunhofer ILT. Univer- turing and engine building companies. sity courses are drawn up jointly as well. The interdisciplinary collaboration Contact between physicians and engineers, for Prof. Dr. Reinhart Poprawe M. A. instance, has resulted in a university Phone: +49 (0)241/8906-109 seminar for advanced dental training Fax: +49 (0)241/8906-121 being set up. Teaching, research and [email protected] innovation – those are the bricks with which the three university departments and the Fraunhofer ILT are building the future.

28 Fraunhofer ILT Annual Report 2006 Laser Technology at RWTH Aachen

Chair for the Technology Study and research department of Optical Systems TOS for the non-linear dynamics of laser production methods NLD By establishing the Chair for the Tech- nology of Optical Systems in 2004, Founded in 2005, the study and re- RWTH Aachen accorded recognition to search department for the non-linear the increasingly central role of highly dynamics of laser production methods developed optical systems in manufac- NLD complements the system-oriented turing, the IT industries and the life R&D activities of the LLT and TOS de- sciences. Research activities focus on partments. the development and integration of optical components and systems for The goal of non-linear dynamics is laser beam sources and laser devices. to investigate technical systems by mathematical, physical and experimen- Highly corrected focusing systems for tal means and to make these research a high laser output, beam homogeni- findings available for industrial zation facilities and innovative beam production and teaching purposes. shaping systems are all key compo- nents of laser systems used in produc- Solving equations to determine the tion engineering. The performance continuum limit in physical systems of fiber lasers and diode-pumped solid- makes it possible to analyze flow state lasers, for instance, is determined patterns in process gases and molten by optical coupling and pump light charges that constitute boundary homogenizers. Waveguide structures layers, for instance. It is only through for frequency conversion are yet an- simulation and modeling, moreover, other topic of research. In the area of that thermal radiation during welding high-power diode lasers, micro- and can be diagnosed. macro-optical components are deve- loped and combined to form complete The application of mathematical systems. In addition, assembly tech- models not only makes it easier to niques are optimized. understand dynamic processes, but actually gives rise to entirely new pro- Contact duction engineering concepts. Thanks Prof. Dr. Peter Loosen to the close cooperation with the Phone: + 49 (0)241/8906-162 Fraunhofer ILT, the insights gained can Fax: +49 (0)241/8906-121 be directly implemented in industrial [email protected] laser materials processing. As an ex- ample, online monitoring systems are systematically expanded and adapted to meet practical needs.

Contact Prof. Dr. Wolfgang Schulz Phone: +49 (0)241/8906-204 Fax: +49 (0)241/8906-121 [email protected]

Fraunhofer ILT Annual Report 2006 29 Cluster of Excellence »Integrative Production Technology for High-Wage Countries«

A similar divergence is evident with res- Cluster of Excellence pect to the second factor, that of plann- ing efficiency. Manufacturers in high- In the Cluster of Excellence »Integra- wage countries aim to continuously tive Production Technology for High- optimize their processes, using corres- Wage Countries«, for which DFG pondingly sophisticated, capital-intensive funding was approved in October 2006, planning methods and instruments, process engineers and materials scien- and technologically superior production tists based in Aachen are developing systems. In low-wage countries, by new concepts and technologies offer- contrast, production needs are better ing a sustainable approach to industrial served by simple, robust, supply-chain- manufacturing. oriented processes.

A total of 18 chairs and institutes In order to maintain a sustainable com- of RWTH Aachen, together with the petitive advantage for production sites Fraunhofer Institutes for Laser Techno- in high-wage countries, it is no longer logy ILT and for Production Technology sufficient to aim for a better position IPT, are working on this project, which that maximizes economies of scale in the first instance will run until the and scope or reconciles the opposing end of 2011. extremes of a planning-oriented and a value-oriented approach. Instead, the Funding of approx. 40 million euros goal of research must be to cancel out has been granted to this Cluster of these opposite poles as far as possible. Excellence, an initiative that unites the Ways must be found to allow a greater largest number of research groups in variability of products while at the Europe devoted to the objective of same time being able to manufacture preserving manufacturing activities in them at cost levels equivalent to mass high-wage countries. production. This calls for value-optimized supply chains suited to each product, without excessive planning overheads The production dilemma: Scale/scope that would compromise their cost- vs. planning-oriented/value-oriented, Production in high-wage countries effectiveness. source: WZL Aachen. The competition between manufac- Tomorrow’s production technology turers in high-wage and low-wage therefore requires a thoroughly new countries typically manifests itself as understanding of these elementary, a two-dimensional problem, opposing interrelated factors. production efficiency and planning efficiency.

In each case there are divergent ap- Integrative production proaches. With respect to production efficiency, low-wage countries tend The Cluster of Excellence »Integrative to focus exclusively on economies of Production Technology for High-Wage scale, whereas high-wage countries Countries« is aiming for the long-term are obliged to seek a balanced equili- goal of increasing the competitiveness brium between scale and scope, in of German production technology. The other words being able to satisfy cus- overarching hypothetical solution lies tomer requirements in respect of a in achieving the next higher level of particular product while at the same production integration. time attaining a minimum production volume.

30 Fraunhofer ILT Annual Report 2006 Cluster of Excellence »Integrative Production Technology for High-Wage Countries«

Individualized production Self-optimizing production

Individualized production involves Self-optimization is a way of optimiz- allowing for a high degree of product ing production processes without variability and dynamics at costs equi- increasing the volume of upstream valent to those of mass production. planning activities. In the cluster Concepts are being developed that will domain Self-optimizing Production, enable the optimum combination and methods and technologies are being configuration of the different elements developed to increase the cognitive in a production system to be identified. capabilities of production systems such At the same time, advanced manufac- as a laser cutting plant or an assembly turing technologies such as selective system for optical components. laser melting (SLM) are being further refined, and will eventually enable one-piece-flow concepts to be imple- mented at the same costs as mass Contacts production. Fraunhofer ILT The official opening of the Dipl.-Phys. Christian Hinke Cluster of Excellence in October Phone: +49 (0)241/8906-352 2006, source: WZL Aachen. Virtual production [email protected]

The introduction of greater flexibility in Cluster of Exellence Office production processes necessarily results Dr. Frank Possel-Dölken in an increased volume of preparatory Phone: +49 (0)241/80-27590 and planning activities. In the cluster [email protected] domain Virtual Production Systems, the aim is therefore to improve plann- ing quality while simultaneously re- ducing the quantity of work involved. This is being done by developing dis- crete models representing, for instance, laser welding processes and materials, linking them together and integrating them in a virtual supply chain.

Hybrid production

By integrating a number of discrete processes in a single hybrid process, it is possible to reduce the length of supply chains and hence organize them more efficiently. In the cluster domain Hybrid Production, methods are being investigated that will enable supply chains to be systematically hybridized, and hybrid technologies such as laser-assisted incremental sheet Source: WZL Aachen. forming are being developed.

Fraunhofer ILT Annual Report 2006 31 PhotonAix e. V. Competence Network for Optical Technologies

Short Profile Highlights 2006

PhotonAix, the Competence Network Besides participating in Photonics West for Optical Technologies and Systems, 2006 in San Jose, USA, and Optatec was founded in 2002 by the Fraun- 2006 in Frankfurt as a joint exhibitor hofer Institute for Laser Technology ILT, with the other German competence the Fraunhofer Institute for Production networks for optical technologies, the Technologies IPT and the Laboratory major event of 2006 was the establish- of Machine Tools and Production ment of the European technology plat- Engineering WZL of the RWTH Aachen. form Photonics21. Following the for- Aachen-based PhotonAix and eight mal acceptance by Brussels of the other regional competence networks proposal to create the technology plat- made up of more than 400 members form in December 2005, PhotonAix from research and industry are concen- was heavily involved in the drafting of trating their skills with the mutual goal a Strategic Research Agenda. of promoting optical technologies in their respective regions. The Strategic Research Agenda entitled »Towards a Bright Future for Europe«, These competence networks represent which will form the basis for collabora- the full range of »Made in Germany« tive research on optical technologies in optical technologies, from laser-based Europe, was submitted to the Commis- materials processing and biophotonics sioner for Information Society and to transportation and aerospace appli- Media, Viviane Reding, in April 2006. cations. The networks are primarily engaged in providing services such Seven thematic workshops (on Infor- as technology management, start-up mation and Communication, Industrial consulting, regional technology and Production/Manufacturing and Quality, Professor Reinhart Poprawe industry marketing, quality training Life Sciences and Health, Lighting and among the members of the and education initiatives, and fostering Displays, Metrology and Sensors, Board of Stakeholders of the communications within the network. Design and Manufacturing of Compo- European technology platform Photonics21. The regional concentration of expertise nents and Systems, Photonics Research leads to practical, real-time problem and Education and Training) were resolution and an accelerated transfer held in December 2006 to identify of research results into market-ready appropriate themes for future research products. projects.

Contact

PhotonAix e. V. Dipl.-Phys. Christian Hinke Managing director Steinbachstraße 15 52074 Aachen

Phone: +49 (0) 241/8906-352 Fax: +49 (0) 241/8906-121 [email protected] www.photonaix.de

32 Fraunhofer ILT Annual Report 2006 Laser and Plasma Sources Business Area Laser and Plasma Sources

This business area encompasses the development of diode laser modules and systems as well as diode-pumped solid-state lasers with different reso- nator structures (stab,slab,fiber), the design of new diode laser structures, the microassembly of diode lasers and optical components, and the develop- ment of plasma systems.

For more than 10 years spinn-offs of the Fraunhofer ILT are set up in the framework of some projects. In coope- ration with the Fraunhofer IAF new structures are being designed which permit the manufacture of diode lasers demonstrating higher beam quality. The business area continues to enjoy a unique reputation in the assembly of high-power diode lasers and in particular the installation of automated assembly and test facilities. Work in Direct generation of pulsed the plasma technology sphere focuses laser beams at 935 nm with mixed-garnet crystals. on the development of EUV beam sources for semiconductor lithography. The main target markets for the busi- ness area as a whole are laser machining, medical engineering and metrology, along with the component market for information and communications tech- nology.

34 Fraunhofer ILT Annual Report 2006 Contents

Visualization and optimization Diode-seeded fiber amplifier for of flow in microchannel heat sinks 36 LIDAR applications 48

Assembly of diode laser bars using Direct generation of pulsed gold-tin vapor deposition 37 laser beams at 935 nm with mixed-garnet crystals 49 Emitter-resolved characterization of diode laser bars 38 Ultra-stable single-frequency oscillator-amplifier configuration Characterization facility for with high average output power 50 collimated and uncollimated diode lasers 39 Numerical modeling of ytterbium-doped slab amplifiers 51 Pump module for frequency doubling of 405 nm wavelength 40 Computation of unstable resonators for laser altimeters 52 Raman pump source with 4 wavelengths based on high-power Fiber-integrated base module diode lasers 41 for multi-kilowatt fiber lasers 53

Fiber-coupled diode laser Numerical simulation of non-linear beam source of high spectral three-wave coupling in waveguide and spatial brilliance 42 structures 54

Fiber-coupled diode-laser Beam source delivering pump module for the BepiColombo wavelengths in the water window space probes 43 region for X-ray microscopy 55

Development of homogenization EUV microscopy for defect optics for a bichromatic diode laser 44 inspection on surfaces and thin films 56

Q-switched Nd:YVO4 oscillator on a customer-specific platform 45 Energy monitor for extreme ultraviolet radiation 57 Frequency-stabilized pulsed lasers for aerospace LIDAR applications 46 Simulation of laser-induced vacuum discharge 58 A highly efficient laser pulse source for satellite-based atmospheric research with LIDAR 47

Note from Institute Director We would like to point out that the publication of the following industry projects has been coordinated with our customers. In principle, industry projects are subject to the strictest obligation to maintain secrecy. We would like to take this time to thank our industrial partners for their willingness to have their reports listed published.

Fraunhofer ILT Annual Report 2006 35 Visualization and optimization of flow in microchannel heat sinks

Task Results and Applications

Microchannel heat sinks for diode lasers PIV measurements carried out on a have a limited service life because they 2:1 model of a heat sink reveal distinct quickly exhibit signs of wear. Erosion by areas of turbulent flow in the vicinity the cooling medium as a result of turbu- of channel inlets. The measurements lence and separation zones in the heat clearly show the effect of the flow ve- sink is one limiting factor. Excessively high locity on the formation of boundary- local temperatures due to inefficient cool- layer flow patterns in the microchan- ing in the microchannels can also result nels. The different throughput in the in premature failure of the diode laser. Vi- individual channels can also be dis- sualization of these problem zones helps cerned. Varying the flow velocity causes to identify vulnerable areas in a heat sink. the boundary-layer flow in the chan- Any necessary changes to the design or nels to enlarge to different extents. the boundary conditions are checked by This results in a less than optimum means of FEM calculations. cooling performance, because parts of the channel wall are not in contact with the flow and therefore cannot dissipate any heat. Design changes are Method being made to the heat sink to rectify this situation. CFD simulations help Particle Image Velocimetry (PIV) is a to adapt the geometry and directly non-contact optical measuring tech- visualize the effect on cooling perfor- nique that enables quantitative and mance. qualitative statements to be made about flow properties in complex geo- metries. Particles admixed with the water make it possible to visualize the Contact flow using PIV. The particles are illumi- nated by laser in a certain plane, after Dipl.-Ing. M. Leers, Tel.: -343 which a series of digital images is made [email protected] in quick succession. A software pro- Dr. K. Boucke, Tel.: -132 gram evaluates the images and gene- [email protected] rates a vector-based flow diagram. The results thus obtained are compared with flow simulations (CFD). Design improvements are made in the critical areas and verified with the aid of further simulations. A more efficient cooling performance can also be achieved by Above: Visualization of flow adapting boundary conditions such as velocities using PIV. Middle: Magnified image of flow velocities. the flow pattern at the tip of a microchannel. Below: Result of flow simulations at the inlet to the microchannels.

36 Fraunhofer ILT Annual Report 2006 Assembly of diode laser bars using gold-tin vapor deposition

Task Results and Applications

Conventional heat sinks for diode la- An EDX analysis of the solder’s stoichio- sers are made of copper. The laser bars metrical composition confirms the re- are mounted with a soft solder mate- quired mass ratio of 80 percent gold to rial, usually indium. One of its functions 20 percent tin. At the same time, solder- is to compensate for the different ing tests reveal flawless wetting of the coefficients of thermal expansion po- solder. ssessed by the heat sink and the laser Laser bar AuSn bar. Particularly in pulsed operation, The optical performance data of laser these soldered bonds do not always bars assembled on heat sinks with remain stable for long periods. matched thermal expansion using gold- tin solder are not different from those WCu Compensation with soft solder is not of indium-soldered bars. Investigations required if the heat sinks used are have shown that the stresses induced nickel matched to the thermal expansion pro- in the laser bar are minimal. One of 100 µm perties of the laser bars. In this case, the main causes of the previously expe- hard solders that remain stable over rienced aging deterioration has thus Above: Dome-shaped section long periods such as eutectic gold-tin been eliminated. The combination of through a laser bar assembled alloy (AuSn) can be used. The solder heat sinks with matched thermal expan- using gold-tin solder. is provided either as a preform or as a sion and gold-tin soldering of the laser Below: Laser bar mounted on a heat sink with matched thermal layer applied to the heat sink. A process bars means that a long service life can expansion using gold-tin solder. for vapor deposition of eutectic AuSn be expected. solder layers was developed in the con- text of a project at the Fraunhofer ILT.

Contact

Method Dipl.-Ing. M. Leers, Tel.: -343 [email protected] The vapor deposition of the solder on Dr. K. Boucke, Tel.: -132 the heat sinks is carried out in a high [email protected] vacuum using two vaporizers for the basic materials of gold and tin. Para- meters such as the quantity of material to be vaporized, the vapor deposition rates and the order of the layers are varied in order to create the necessary layer thicknesses and the overall com- position. Dome-shaped sections are cut in order to verify the correct structure of the individual layers using REM and EDX. This is followed by re- flow tests to determine the behavior of the solder during the process and the liquidus temperature. The composition of the solder can be determined by examining the melted samples.

Fraunhofer ILT Annual Report 2006 37 Emitter-resolved characterization of diode laser bars

Task Results and Applications

To obtain a more detailed analysis of The test bench constitutes an extension the packaging and aging of diode laser of the semiautomatic electro-optical bars, a test bench that enables emitter- characterization facility. It has made resolved measurements is required. emitter-resolved intensity and polariza- The purpose of this test bench is to tion measurement a standard compo- measure laterally resolved intensity, nent of characterization. wavelength and polarization distribu- tions reliably and with as few adjust- The position of the emitter focal points ments as possible. This information in fast-axis (smile) can be measured allows the packaging layout and also with a resolution of 0.4 µm. The emit- the aging to be analyzed and qualified ter spectra are determined with a rela- for each emitter. The wavelength dis- tive resolution < 0.2 nm, enabling late- tribution reflects the temperature dis- ral temperature variations < 1 K to be tribution. The polarization distribution displayed. The degree of polarization provides information about the inter- of individual emitter beams is deter- nal mechanical stress in the laser bar. mined with an error rate of < 1 %. Above: Layout of the test bench. Below: Smile, wavelength and polarization measurement. Since the measurement is performed simultaneously for all emitters, time- Method resolved measurements are possible, for instance during pulsed operation The test bench maps the emission of the diode laser. facet of the laser bar onto a CMOS camera. The lens is so designed that it possesses a wide depth of focus, in order to minimize the adjustments Contact ] m µ

[ necessary for each separate measure- e l i

m ment. Attenuating elements enable Dipl.-Phys. T. Westphalen, Tel.: -423 s the laser bar to be measured both [email protected] above and below the laser threshold. Dr. K. Boucke, Tel.: -132 ] m

n The camera images and the test bench [email protected] [ h t are analyzed and controlled by a soft- g n e l

e ware program. v a w The relative intensity distribution, the e e

r position of the emitters and thus the g e d “smile” can be determined in the basic n o i t configuration. The polarization degree a z i r a

l of the emitters can be determined by o p inserting a polarization filter into the

emitter beam path. A laterally resolved wave- length spectrum is mapped onto the camera via a grid positioned in the beam path.

38 Fraunhofer ILT Annual Report 2006 Characterization facility for collimated and uncollimated diode lasers

Task Results and Applications

There are many applications where it The characterization facility is suitable is important to know the radiation for measuring both diode laser bars and characteristic of the diode lasers em- whole stacks. The measurements can ployed. The task is therefore to deve- be performed in continuous or pulsed lop a facility that can be used for com- operation. The maximum operating plete, automated characterization of current is 150 A for cw operation and high-power diode lasers and stacks. 200 A for qcw operation, and the maxi- The following optical and electro-opti- mum operational voltage is 25 V. Pulse cal properties are to be determined in lengths of 400 µs to 20 ms can be tes- a single series of measurements: ted in pulsed operation. Beam diver- • Beam divergence angle (in fast gence angles of up to ± 60° with a and slow axis) resolution < 0.2 mrad can be measured • Wavelength in the fast axis, and beam divergence • PUI characteristic angles of up to ± 15° with a resolution < 5 mrad can be measured in the slow The diode lasers to be measured axis. The beam divergence angle is can be actively or passively cooled and determined by the FWHM, 1/e2 or the either collimated or uncollimated. 95 percent method. The wavelength measurement resolved into individual bars is carried out with a spectrometer in a range from 780 to 1000 nm with Method a resolution of 0.25 nm. The thermal measuring head is capable of measuring To determine the beam divergence a total output of up to 1 kW. angle in fast axis direction, the diode laser is revolved around a rotational axis, and to determine the beam diver- Above: View of the overall gence angle in slow axis direction the Contact facility with PC workstation emitted beam is deflected with the aid (left) and optics box (right). of a scanner mirror. The angle-depen- Dipl.-Ing. (FH) K. Wieching, Tel.: -195 Below: Detailed view of the dent intensity is registered by a photo- [email protected] three-part measuring setup (beam initial divergence angle, diode whose distance from the diode Dr. K. Boucke, Tel.: -132 wavelength and PUI measure- laser can be varied. This means that [email protected] ment). both collimated and uncollimated diode lasers can be measured.

To measure the wavelength of diode laser stacks resolved into individual bars, the stack is moved past an adju- stable aperture. The laser beam impin- ges on a detector which is connected to a spectrometer via an optical wave- guide. The relative motion of the diode laser with respect to the aperture en- ables the output and a wavelength dis- tribution across the stack to be deter- mined. To measure the PUI characteris- tic the diode laser is moved directly in front of a thermal measuring head.

Fraunhofer ILT Annual Report 2006 39 Pump module for frequency doubling of 405 nm wavelength

Task Results and Applications

The first diode lasers with a wave- With an operating current of 5 A, length of 405 nm are now commercial- the module delivers an optical output ly available, but their maximum CW power in excess of 3 W. The wave- output of approximately 50 mW is still length can be varied between 787 and relatively low. Higher output values can 803 nm by changing the position of be achieved by applying the principle the grating at a cooling temperature of of frequency doubling, in which a crys- 18°C. The spectral width of the emit- tal is pumped at a wavelength of 810 ted light was measured as < 0.1 nm nm so that it will emit 405 nm after (intensity at 1/e2). frequency conversion. Taking a tapered amplifier as the basis, the task was to The frequency tuning range can be develop a frequency-stabilized pump adapted to the respective requirements module with as narrow a bandwidth as by selecting the most suitable tapered possible and close to diffraction-limited amplifier and by varying the operating beam quality, whose output power is temperature. > 2 W and whose wavelength can be Structure of the pump module. freely adjusted within a range of ap- prox. 10 nm. Contact

Dip.-Ing. M. Haverkamp, Tel.: -442 Method [email protected] Dr. K. Boucke, Tel.: -132 To stabilize the frequency of the tapered [email protected] amplifier, the emitted beam is collima- ted on the back side by an aspherical lens. The beam falls on a blazed grating, positioned in the Littrow configuration. Depending on its angle of inclination, a certain wavelength is refracted back into the laser, thus building up an ex- ternal resonator. On the front side, the laser beam is collimated by a rotation- symmetrical aspherical lens in fast axis and subsequently by a cylindrical lens in slow axis to compensate for the astigmatism. To ensure a high longi- tudinal mode stability, the resonator length must not vary by more than λ/2 (400 nm) as a result of thermal influ- ences. To ensure that this is the case, the laser is temperature-regulated and all resonator components susceptible to thermal expansion are made of silica glass, which possesses a very low coefficient of thermal expansion of only ≈ 0,5 x 10-6/K (at 20°C).

40 Fraunhofer ILT Annual Report 2006 Raman pump source with 4 wavelengths based on high-power diode lasers

length. This corresponds to an output Task of 400 mW in the SMF at a wave- length of 1426 - 1480 nm. Four fre- In contrast to doped-fiber amplification, quency-stabilized modules are integra- Raman amplification produces lower ted in a pump source prototype using amplifier noise and higher amplification, fiber Bragg gratings at wavelengths and opens up further amplification of 1426 nm, 1435 nm, 1444 nm and bands besides the C-band and the 1480 nm. Thanks to the grating, the L-band. This means that Raman am- amplification spectrum is not depen- plifiers are of great interest to the dent on the temperature or the diode

telecommunications market for signal operating current. The four wave- n o i t a

transmission over long fiber-optic lengths are coupled in a SMF with c i f i l routes. the aid of a fusion coupler, thus gene- p m a

rating an optical pump output of f f o /

In order to generate a flat amplification 1.1 W on 4 wavelengths. The entire n o spectrum with a width of 100 nm, pump source is housed in a 19’’ plug- for example, multi-wavelength pump in module. sources are needed. These are built wavelenth either on the basis of fiber lasers or on the basis of high-power diode lasers. Multi-wavelength Raman pump sour- Results and Applications ces (MWRP) based on fiber lasers have the drawback that it is not possible to With a CW signal output of -3 dBm, adjust the output of individual wave- a fiber length of 52.8 km SMF and a lengths without affecting the outputs pump output of 1.1 W running counter of other wavelengths, and their relative to the signal direction, the new MWRP intensity noise is greater than in high- delivers an amplification spectrum power diode lasers. As a result, the of 60 nm in the C-band (1520 nm - only feasible way of pumping is in the 1580 nm) with 12 dB on/off amplifi- opposite direction to the signal. The cation, an optical signal-to-noise ratio Above: On/Off amplification aim of this project is therefore to deve- of 43 dB and a flatness of < 1.5 dB. in the C-band for signals with lop a high-output MWRP based on In contrast to Raman fiber lasers, the an output of -3 dBm. high-power diode lasers. MWRP developed is also capable of Below: Raman pump source. pumping in the same direction as the signal.

Method The results demonstrated were achieved in a joint project by the Fraunhofer In- Since Raman amplification increases stitutes HHI, IAF and ILT. exponentially with the pump output, and the output of diode lasers is limi- ted due to inherent properties, a highly efficient way of coupling the pump la- Contact sers in single-mode fibers (SMF) is nee- ded. The optical construction tested in Dipl.-Ing. M. Haverkamp, Tel.: -442 the laboratory was successfully trans- [email protected] formed into a laser module, making it Dr. K. Boucke, Tel.: -132 possible to achieve a coupling efficien- [email protected] cy of > 80 % in the module when using single-mode lasers in conjunction with aspherical lenses of short focal

Fraunhofer ILT Annual Report 2006 41 Fiber-coupled diode laser beam source of high spectral and spatial brilliance

Task Results and Applications

Fiber-coupled diode lasers with optical A fiber with a diameter of 600 µm is output powers in the multi-kilowatt used to generate a laser beam output range are increasingly competing of 952 W within a numerical aperture against solid-state lasers as a direct of 0.175 (95 % power inclusion). The beam source for materials processing. spectrum of the wavelength-stabilized A novel spectral beam superposition diode laser features narrowband emis- technique provides the brilliance of a sion of the four center wavelengths lamp-pumped solid-state laser. within a spectral width of less than 1 nm in the entire power range.

Owing to its spatial brilliance, the Method diode laser is suitable for direct applications in materials processing, The brilliance of diode lasers is increased such as the welding of thin-sheet alu- by spectral superposition of individual minum. Its high spectral brilliance also beam sources. The state of the art is allows the efficient optical pumping Above: 1-kW diode laser with fiber coupling (fiber diameter to use dielectric filters for beam super- of fiber and solid-state lasers within 600 µm, housing dimensions position. This method requires a gap narrowly limited pump bands. 700 x 550 x 220 mm3) and pro- of 20 nm to 30 nm between the diode cessing optics (image scale 4:1). Below: Partial view of six wave- laser wavelengths, thus only permitting length-stabilized diode laser a limited number of beams to be super- modules with dual beam super- imposed in the wavelength range Contact position at a close wavelength of high-power diode lasers. Current spacing of 3 nm. developments in this area build on Dipl.-Ing. C.Wessling, Tel.: -467 wavelength stabilization and spectral [email protected] superposition with volume diffraction Dipl.-Ing. H.-D.Hoffmann, Tel.: -206 gratings to increase brightness. The [email protected] emission bandwidth of a diode laser is reduced, and the laser beams are selected and superimposed with their center wavelengths very close together.

The diode lasers are stabilized at 908 nm, 911 nm, 975 nm and 978 nm respec- tively. With volume diffraction gratings, this fourfold spectral superposition is carried out at a center wavelength spacing of 3 nm.

42 Fraunhofer ILT Annual Report 2006 Fiber-coupled diode-laser pump module for the BepiColombo space probes

Task Results and Applications

In 2012, ESA plans to launch two space The Fraunhofer ILT has developed the probes on an exploratory mission to optical and mechanical design of the Mercury. The BepiColombo mission will pump module, and successfully built employ a laser altimeter to produce a and tested its prototype. During tests, topographical map of the planet. By a peak pulse output of 530 W was scanning the surface with this instru- achieved at the fiber output. The mo- ment and measuring the propagation dule weighs 650 g and measures 150 delay of the reflected laser pulses, it x 50 x 50 mm. The module's flexible will be possible to create a spatially switching arrangement allows reliabili- resolved elevation profile of Mercury. ty to be increased at lower output The solid-state laser employed by the power by means of cold redundancy. instrument will incorporate a fiber- The modular structure of the pump coupled, pulsed pump source, which module also enables it to be easily is being developed on behalf of TESAT adapted to the requirements of other Spacecom GmbH & Co. KG in Back- missions. nang. Its design has to take into ac- count the special requirements of this application in terms of size, weight and robustness. Contact

Dipl.-Ing. M. Traub, Tel.: - 342 [email protected] Method Dipl.-Ing. H.-D. Hoffmann, Tel.: - 206 [email protected] In order to obtain the required output power, several diode laser bars are jointly coupled into a fiber with a core diameter of 800 µm. Unlike in previous designs, this pump module is built using a planar arrangement of the bars, which are mounted on individual Prototype of the fiber-coupled heat sinks. This enables each bar to diode-laser pump module. be qualified separately and allows the heat to spread more easily than in con- ventional vertical stacks. To shape the beam for efficient fiber-coupling of the bars, extensive use has been made of off-the-shelf components and assem- bly methods used in previously quali- fied cw pump modules that are already being produced in large volumes. This will simplify the task of qualifying the pump module for use in space applica- tions.

Fraunhofer ILT Annual Report 2006 43 Development of homogenization optics for a bichromatic diode laser

an optimum heating process for each Task different component geometry. An ex- tremely homogeneous distribution is The surface processing of fiber-rein- also to be generated. Because the ho- forced plastic components has so far mogenization optics, together with the been carried out in a special produc- laser head, are to be fixed onto a robot tion process at the Dutch company arm, the system's design has to be as AFPT using high-power diode lasers compact and light as possible. In order whose beam shape is not adapted to to meet the special requirements of the process. The power density distri- industrial mass production, the optics bution of commercial diode laser sys- must be hermetically sealed and water- tems leads to undesirable temperature cooled. gradients which, due to local melting, have a negative effect on the results of this application. In an innovative process, a rectangular diode laser beam Results and Applications with homogeneous power density distribution is to be used. This will help A beam-shaping lens system for the to make the production process more specified diode laser was set up at the economical and more reproducible. Fraunhofer ILT and successfully quali- fied in collaboration with the Fraunho- fer IPT and AFPT. This system can pro- vide homogeneous power density dis- Method tributions in the machining plane with dimensions of 20 mm x 40 mm, 40 mm The beam source employed is a bichro- x 40 mm and 11 mm x 40 mm. Thanks matic diode laser built by Rofin Sinar to their size- and weight-optimized with a maximum output of 2.1 kW. design, the optics measure as little as The Fraunhofer ILT has developed flexi- 200 mm x 60 mm x 60 mm and weigh ble beam-shaping optics which provide only 1450 g. In collaboration with the a customized, process-optimized Fraunhofer IPT, the industry-standard power density distribution. This enables beam-shaping optics were integrated the lens to be adapted to different into the existing installation. The optics beam geometries in order to achieve helped to achieve a transfer efficiency Beam-shaping optics. of 90% and a homogeneity of over 90%.

Contact

Dipl.-Ing. M. Traub, Tel.: - 342 [email protected] Dipl.-Ing. H.-D. Hoffmann, Tel.: - 206 [email protected]

44 Fraunhofer ILT Annual Report 2006 Q-switched Nd:YVO4 oscillator on a customer-specific platform

Task Results and Applications

At the request of a customer, a marking The laser was implemented according laser was to be integrated in an existing to the customer's specifications. The laser welding system. In order to avoid result is a robust, near-production pro- an expensive retrofit of the given instal- totype. The overall height of the con- lation, the marking laser had to be set trol units, including the water-air coo- up on a platform whose mechanical, ler, is 6 HU. The laser was integrated optical and electrical interfaces were into the existing system. precisely adapted to the existing system. The available platform can be employed for a variety of applications, and is cur- rently being used as a base for setting Method up a UV source.

The mechanical interfaces of a plat- form developed at the Fraunhofer ILT were adapted to the existing installation Contact Near-production prototype according to the customer's specifi- of an Nd:YVO4 oscillator. cations. Dipl.-Phys. D. Esser, Tel.: -437 [email protected] In order to meet the requirements im- Dipl.-Ing. H.-D. Hoffmann, Tel.: -206 posed on the electrical interfaces, such [email protected] as a separate shutter control and ad- ditional interlock circuits, the power supply unit of a commercially available diode laser was modified to suit the customer's wishes. In addition, an AOM driver was integrated in the power supply unit. The marking laser is pumped with a high-power laser diode and, depending on the selected work- ing point, has an average laser output of up to 6 W with a good beam quality in Q-switched mode. The output beam of the oscillator was adapted to the customer's processing optics.

Fraunhofer ILT Annual Report 2006 45 Frequency-stabilized pulsed lasers for aerospace LIDAR applications

The methods being developed to ad- Task just the resonator length are based on measurements of the seed signal and High-resolution measurements of wind enable the suppression of mechanical speeds or the concentration of gases oscillations up to the multi-kHz range.

such as water vapor, methane and CO2 in the atmosphere using LIDAR (Light Detection And Ranging) require highly stable narrowband laser pulses with Results and Applications pulse energies in the range of 10 - 100 mJ and bandwidth-limited pulse dura- The resulting oscillators achieve pulse tions in the range of 10 - 100 ns. These energies of 12 mJ and M2 < 1.1 during are normally generated by seeding a seeded and frequency-stabilized ope- Q-switched laser with a highly stable ration with a pulse repetition rate of low-power narrowband laser source 100 Hz and a pulse duration of 30 ns. while actively stabilizing the resonator Within a temperature range of 12 °C, length. their pulse energy fluctuates by less than two percent. Systems used in laboratories, where Laboratory setup of a passively cooled, frequency-stabilized there is little mechanical interference, The 'Ramp-Delay-Fire' control process oscillator with a piezo-actuator the so-called pulse-build-up control developed by the researchers enables for active length adjustment. process is often used, which can only a frequency stability of < 1 MHz (rms), suppress mechanical oscillations below a pulse bandwidth of less than 8 MHz the pulse repetition rate. (FWHM) and an exceptionally high fre- quency stability even under the influ- The systems required for aerospace ence of major disturbances to the reso- applications have a pulse repetition rate nator length. At a parasitic frequency of 100 Hz and must ensure frequency- of 1.05 kHz and an amplitude of 160 stable operation even in the presence nm, for example, a frequency stability of parasitic oscillations in the kHz range, of 3 MHz (rms) is recorded, while at with amplitudes of changes in the re- 320 nm the stability lies at 8 MHz. In sonator length in the range of several contrast to previously used methods, it tens of nanometers. is still possible under these circumstan- ces to predict the pulse emission accu- rately to within just a few nanose- conds. Method

The researchers are developing entirely passively cooled, Q-switched funda- Contact mental-mode oscillators with a high efficiency and low sensitivity to misa- Dipl. Phys. K. Nicklaus, Tel.: -224 lignment and temperature fluctuations. [email protected] These characteristics are to be achieved Dipl. Ing. H.-D. Hoffmann, Tel.: -206 by means of a compact structure in [email protected] combination with a fault-tolerant reso- nator design.

46 Fraunhofer ILT Annual Report 2006 A highly efficient laser pulse source for satellite-based atmospheric research with LIDAR

ser crystal and the beam path. Any Task parasitic effects competing against the amplification of the laser pulses are mi- Spatially resolved measurements of nimized. The special geometry of the concentrations of molecules (such as InnoSlab laser provides the ideal basis water vapor or carbon dioxide) or ae- for this task and also renders the system rosols in the atmosphere using LIDAR insensitive to ageing of the pump diodes (Light Detection And Ranging) require and temperature fluctuations. highly stable, narrowband, short laser pulses of high energy. The key criteria when selecting a suitable laser source for satellite-based operation are that Results and Applications the system be reliable and efficient, and of a compact and light design. Successful tests with the laser oscillator were followed by a series of experi- As part of a project currently being im- ments to optimize the amplifier. These plemented together with EADS ASTRI- tests were carried out using a flexible UM to design a 'pre-development mo- laboratory setup which will later be del', a laser source is being developed translated into a compact design that which generates laser pulses with an closely corresponds to the actual di- energy of at least 70 mJ and a wave- mensions of the final laser system. A length of 1064 nm at a repetition rate special feature of this design is that it of 100 Hz. These laser pulses are then incorporates redundant pump diodes Preliminary design of the satellite- tripled in frequency with the help of to compensate for diode failures with- based laser source (exploded nonlinear crystals. The system should out affecting the overall performance. diagram). be capable of operating in space for at least 3 years. Cascaded amplifier stages featured in the design provide an excellent means of scaling to higher pulse energies such as those required, for example, in LIDAR systems used for molecule Method detection.

A Q-switched, stable resonator with a diode-pumped Nd:YAG rod serves as the laser oscillator. Pulse generation is frequency-stabilized with the help of Contact a seed laser. This enables laser pulses with an energy of 8 mJ to be genera- Dipl.-Phys. J. Luttmann, Tel.: -128 ted in excellent spatial and temporal [email protected] quality. Dipl.-Ing. H.-D. Hoffmann, Tel.: -206 [email protected] Downstream of this is a diode-pumped Nd:YAG amplifier operating according to the InnoSlab principle, which ampli- fies the laser pulses to 70 mJ without sacrificing quality. Given that the slab amplifier largely determines the effi- ciency of the overall system, a series of detailed simulations was carried out to establish the ideal geometry of the la-

Fraunhofer ILT Annual Report 2006 47 Diode-seeded fiber amplifier for LIDAR applications

Task Method

Pulsed LIDAR systems emit short laser In order to meet high demands on tim- pulses and can determine the distance ing, i.e. pulse durations in the sub-ns to diffusely scattering objects by measur- range with low pulse jitter combined ing the signals' time delay. The perfor- with the necessary pulse peak outputs mance potential depends directly on the in the kilowatt range and average out- laser system itself. The repetition rate puts of several watts, the laser must be (approx. 0.5 to 2 MHz) is defined by the designed in an oscillator-amplifier con- number of measuring points required in figuration. The temporal and spectral a given time period. The maximum range properties of the laser pulse are deter- of the measuring instrument is prede- mined by a pulsed laser diode, whose termined by the pulse peak output signal then runs through a two-stage (greater than 1 kW) in connection with fiber amplifier arrangement. Fiber am- the beam quality (M2 < 1.5). Temporal plifiers have several advantages over properties such as pulse duration and laser-rod amplifiers: jitter determine the achievable accuracy. • They do not need adjustment. • The beam parameters are not Above: Laboratory setup of the fiber amplifier. As part of an internal Fraunhofer pro- influenced by the power setting. Below: CAD drawing of gram, the ILT is currently developing a • A high amplification and efficiency the laser module. fiber laser system for scan-based dis- can be achieved. tance measurement together with the Fraunhofer IPM.

Results and Applications

The laser properties required for the given application were demonstrated in the laboratory. The next step is to in- tegrate the fiber optics into a housing and equip them with the necessary control electronics.

Other possible areas of application for this laser system are measurement technologies with temporally shaped laser pulses, micro-material processing or laser-beam drilling.

Contact

Dipl.-Phys J. Geiger, Tel.: -123 [email protected] Dipl.-Ing. H.-D.Hoffmann, Tel.: -206 [email protected]

48 Fraunhofer ILT Annual Report 2006 Direct generation of pulsed laser beams at 935 nm with mixed-garnet crystals

Task Results and Applications

In order to carry out satellite-based During the experiments in qcw mode, measurements of climate-relevant water up to 16 mJ was generated with an vapor distributions with LIDAR/DILAR optical pump energy of 63 mJ. This systems, the running time-dependent corresponds to an efficiency of 25%. absorption of single-frequency pulses With an efficiency of 9%, a pulse is measured. The most suitable wave- energy of 4 mJ was produced for the lengths for such measurements lie in first time in Q-switched mode. Higher the range of 935 - 936 nm and are energies are to be generated in future currently generated with titanium-sap- using suitable InnoSlab amplifiers. phire lasers or optical parametric oscil- lators, which are characterized by low Given that water vapor largely deter- efficiencies and high complexity. Alter- mines the energy balance in the atmos- natively, this wavelength range can phere, robust LIDAR systems with be generated directly in a new type emissions at a wavelength of 935 nm of mixed-garnet crystal. By varying the are likely to be employed on mobile garnet composition of the crystal me- platforms such as aircraft and satellites, dium, the energy levels of the Nd ion but also as ground-based systems. can be specifically adapted to the re- quired wavelengths. The University of Essentially, it is being demonstrated Hamburg has for the first time success- that, by using customized laser crystals fully grown Nd:YGG crystals and de- and adapting the laser's design, it is tected laser emissions in cw mode with possible to generate application-speci- high efficiency at 935 nm. Crystals fic wavelengths directly and efficiently based on this development are to be for both test and measurement and tested in Q-switched mode. materials processing.

Above: Left: Nd:YGG boule made by the ILP. The rod-making Method Contact material has been removed. Right: Nd:YGG boule made Cylindrical Nd:YGG laser rods are Dipl.-Phys J. Löhring, Tel.: -128 by the FFE. Below: Folded resonator with pumped at both ends in a stable folded [email protected] an Nd:YGG crystal pumped at resonator assembly with a pulse repe- Dipl.-Ing. H.-D.Hoffmann, Tel.: -206 both ends. tition rate of 100 Hz. The system is [email protected] Q-switched by means of a Pockels cell.

Fraunhofer ILT Annual Report 2006 49 Ultra-stable single-frequency oscillator-amplifier configuration with high average output power

Task Results and Applications

Metrological and scientific applications After the amplifier stage, the following require long-term-stable, low-noise results were achieved: and extremely narrowband single-fre- • Average output: 45 W quency laser sources with high average • M2: < 1.2 output power and diffraction limited • Wavelength: 1064 nm beam quality. Areas of application in- • Emission spectrum: single frequency clude LIDAR (Light Detection And Rang- • Line width: 1 kHz / 100 ms ing), precision interferometry and the • Tuning range: 30 GHz cooling of atoms in atom traps. In non- • Relative intensity noise (RIN): linear optics, such sources can be used 5 ·10-7 Hz-1/2 (> 10 kHz) together with external resonators for SHG, DFG and OPO processes. In colla- Due to the modular design of the am- boration with INNOLIGHT GmbH, the plifier stage, both actively and passive- researchers are developing compact ly cooled laser diodes can be used as single-frequency laser sources with an a pump source. The amplifier stage average laser output in the range of can be scaled to higher output power Above: Laboratory model of an oscillator-amplifier unit. 10 - 40 watts. Below: Beam profiles after ampli- fier. Above: scaled beam profile in focus. Below: beam profile in far field. Contact Method Dipl.-Phys. M. Höfer, Tel.: -128 A diffraction-limited, ultra-stable, [email protected] nonplanar ring oscillator built by INNO- Dipl.-Ing. H.-D. Hoffmann, Tel.: -206 LIGHT GmbH is amplified from 1 - 2 W [email protected] to 40 - 45 W in a multiple-folded con- figuration using an INNOSLAB amplifier stage. The oscillator's excellent beam properties such as beam quality, polari- zation, spectral bandwidth and low in- tensity noise can be largely preserved in the amplification process.

50 Fraunhofer ILT Annual Report 2006 Numerical modeling of ytterbium-doped slab amplifiers

Task Results and Applications

The suitability of ytterbium-doped laser With the help of these models, the crystals as a lasing medium for the ef- overlap between amplification and laser ficient operation of end-pumped slab mode in the laser crystal and the degree lasers (InnoSlab) is to be investigated of doping in crystals can be optimized. in this study. Ytterbium is utilized as In experimental use, they can provide a laser-active ion in a whole range of insights into the effects of factors such host materials. However, in contrast to as seed and pump capacity and the in- widely employed 4-level systems (e.g. ternal temperature of the laser crystal Neodymium), the interaction between on amplification levels. A suitable diver- pump radiation and laser radiation has gence of the pump radiation in 3-level crystal to be taken into account when ytter- systems can, for example, considerably bium, a pseudo 3-level system, is used increase the efficiency of a laser by re- in diode-pumped solid-state laser sys- distributing the pump capacity in the la- Above: Local intensities in an ytterbium-doped slab crystal. tems. This is, for example, because ser crystal from unused areas to areas Below: Intensity distribution on areas with no pump radiation tend to with high beam intensity. a laser mirror (top and bottom) absorb laser radiation and because of and on a laser crystal (middle). the mutual dependence of the local In conclusion, software tools are now absorption of pump radiation and laser available with which ytterbium-doped radiation. Additionally, the inversion laser amplifiers can be numerically opti- of ytterbium-doped host materials, and mized by simply altering the geometric therefore also their amplification cha- data or the boundary values. racteristics, is temperature-dependant.

Contact Method Dipl.-Phys. T. Mans, Tel.: -379 A software module was employed that [email protected] numerically solves the rate equations Dr. P. Rußbüldt, Tel.: -303 for cw operation on the assumption of [email protected] a thermally relaxed population of the Dipl.-Ing. H.-D. Hoffmann, Tel.: -206 Stark-split sublevels of the upper and [email protected] lower laser levels. This module is inte- grated into a software tool (OPT) that enables the rigorous propagation of complex electromagnetic waves and is also utilized in a further program that enables the propagation of virtually diffraction-limited beams by means of expansion to higher-order modes. The propagation of the pump radiation is taken into consideration in order to establish the level of amplification in the laser crystal and recursion is em- ployed to determine the self-consistent spatial distribution of the inversion and the laser or pump radiation.

Fraunhofer ILT Annual Report 2006 51 Computation of unstable resonators for laser altimeters

Task Method

Laser-based altimeters for use in sa- The OPT software simulation tool tellites require high pulse energies (50 developed by the Fraunhofer ILT is a - 100 mJ) and high beam quality (M2 powerful environment for the compu- < 1.5). However, they must also be tation of diffraction theory problems. robust and of relatively simple con- Intensity and phase distribution of a struction. In stable resonators with a laser beam are represented in two-di- high beam quality, pulse energy is limi- mensional complex matrices. Propaga- ted to a few mJ, necessitating the use tion and the effects of optical elements of elaborate MOPA arrangements to such as mirrors, lasing media or non- achieve the required pulse energy levels. linear crystals are then determined by However, in unstable resonators, high applying operators to these matrices. beam quality can be achieved with With the help of Fox and Li algorithms, high mode volumes, resulting in high the stable intensity distribution and pulse energies. While the design of phase distribution in an unstable reso- stable resonators is generally based on nator can be calculated. relatively straightforward ABCD-matrix calculations, unstable resonators ne- cessitate the use of numerical calcula- tions based on diffraction theory, due Results and Applications Above: Beam profile computed to the lack of any specific analytical so- according to Fox and Li. lutions. These calculations are primarily Suitably robust resonator configurations Below: Basic layout of an unstable resonator. employed to determine the dimensions with the necessary beam quality, effi- of the Gauss-shaped, coated variable ciency and sensitivity for use in satellite- reflectivity mirror (VRM) and the level based altimeters were identified by car- of magnification. rying out numerous parameter studies.

Contact

Dipl.-Phys J. Löhring, Tel.: -128 [email protected] Dipl.-Ing. H.-D.Hoffmann, Tel.: -206 pump-light [email protected]

Q-switch

end mirror VRM reflectivity mirror lasing medium

52 Fraunhofer ILT Annual Report 2006 Fiber-integrated base module for multi-kilowatt fiber lasers

Task Results and Applications

An important characteristic of fiber The suitability of a variety of fiber types lasers is their ability to generate a dif- for operation in the required output fraction-limited beam at average laser range, at a laser output of up to 910 W powers of 1 kW or higher. By employ- and a measured beam quality of M2 = ing fiber-integrated laser components, 1.04 to 1.3, was investigated. rugged, compact setups can be con- structed that allow the fiber laser to Basic pump concepts were analyzed be used as a tool for laser materials and two arrangements were selected processing. for further development. These are currently being built. On the basis of the thermal investigations, a cooling concept could be developed that is Method relatively simple to implement and adequately guarantees the long-term Commercially available active fibers stable operation of all the relevant and fiber-integrated components, such components of a fiber laser with an Above: Fiber laser setup. as fiber Bragg gratings and fiber coup- output power of up to 2 kW. Middle: Measurement of tem- lers, were investigated for their suitabi- peratures in an active fiber. lity for applications in the output range Below: Temperature profile through the cross-section of a of one kilowatt or more. Optimized fiber when cooled on one side active laser fibers were developed and Contact only. tested in collaboration with the Institut für Photonische Technologie IPHT in Dipl.-Phys. J. Geiger, Tel.: -123 Jena, Germany. [email protected] Dipl.-Ing. B. Zintzen, Tel.: -123 A number of pump concepts were [email protected] investigated with regard to relevant Dipl.-Ing. H.-D. Hoffmann, Tel.: -206 characteristics such as preservation of [email protected] beam quality, efficiency, reliability and cost.

A further consideration was the ther- mal management of both active and passive components; these included laser fibers, fiber couplers and splice connections. To this end, measure- ments were performed that enabled to calculate the heat generated by these components. The cooling of the com- ponents was then optimized with the help of FEM simulation.

Fraunhofer ILT Annual Report 2006 53 Numerical simulation of non-linear three-wave coupling in waveguide structures

employed for operations requiring a Task large amount of processing capacity. This combination of programming A current trend in laser design is the languages takes advantage of the development of small laser systems speed of the native compiled C code that rely on waveguide structures to and the flexibility of Python. guide propagation, rather than the free space propagation of radiation fields. This allows considerably smaller diameters to be employed. Small dia- Results and Applications meters are particularly advantageous for non-linear coupling processes, be- The input consists of a so-called signal cause high beam intensities can be ge- wave at a wavelength of 1.5 µm and a nerated with relatively low output le- power of 0.4 W, and two pump waves vels. This is an important prerequisite at wavelengths of 0.98 µm and 0.5 µm. to obtaining high power conversion ef- The phase matching condition, when ficiencies. In the case under considera- the three waves are in phase synchro- tion, radiation with a wavelength of nization, is achieved by periodically 2.83 µm is produced from two radiation switching the polarity of the crystal. Output of the frequency-con- fields with respective wavelengths of The accompanying graph shows the verted idler wave. The rising 1.5 µm and 0.98 µm by generating a output throughout the entire length of steps in the output curve corres- pond to the period length difference frequency. Such systems can the resulting wave, the so called idler of the crystal in successive be optimized by analyzing experimental wave. switching states. results and carrying out simulations.

Contact Method Dr. R. Wester, Tel.: -401 A software tool was developed to nu- [email protected] merically simulate difference frequen- Prof. Dr. W. Schulz, Tel.: -204 cies in periodically polarized non-linear [email protected] crystals. This allows the three waves in the waveguide structure and the non- linear coupling of the three waves to be analyzed with the help of the split step method. Wave propagation is solved by means of semivector appro- ximation using a method based on wide angle beam propagation, and the non-linear coupling of the three waves by numerically integrating the coupling equations (4th order Runge-Kutte me- thod). The algorithms are implemented in the Python interpreted programming language with embedded C code being

54 Fraunhofer ILT Annual Report 2006 Beam source delivering wavelengths in the water window region for X-ray microscopy

Task Results and Applications

Soft X-ray microscopy has the potential Measurement of the 1s2-1s2p transition to open up a wide range of new appli- in helium-like nitrogen at 2.88 nm cations in the fields of biological and showed that the source emitted 1·1014 materials science. High-performance photons per pulse into the half-space. instruments require beam sources ca- This corresponds to an energy of about pable of delivering a brilliance that un- 7 mJ. The lateral half-intensity width of til now has only been provided by the plasma lay in the region of 300 µm. electron-beam storage rings. By deve- Thus, at a discharge frequency of loping high-output compact plasma between 1 and 2 kHz, the source is sources, it will be possible to construct sufficiently brilliant to generate photon laboratory-scale X-ray microscopes. flows on microscopic samples, similar to those observed using instruments connected to a beam line.

Method In addition to their use in laboratory X- ray microscopes, the availability of af- On the basis of our experience with fordable compact beam sources operat- pinch plasmas producing 13.5-nano- ing in the soft x-ray region will permit meter EUV emission, we developed an the development of a new generation efficient source capable of producing of compact instruments for high-reso- line emission at 2.88 nanometers from lution surface structuring and analysis. Three-dimensional represen- tation of beam-source intensity nitrogen plasma. The gas is ionized by (1 pixel represents about 3.7 µm). a pulsed voltage and briefly heated to Characteristics a high temperature. A portion of this • Spectral range: 1 - 10 nm inserted energy is emitted in the form depending on process gas of characteristic soft x-rays. • Frequency: 1 - 2 kHz • Brilliance (nitrogen): 1·1017 Ph/(mm2 sr line) • Power input: 10 kW

Contact

Dipl.-Ing. (FH) M. Benk, Tel.: -137 [email protected] Dr. K. Bergmann, Tel.: -302 [email protected] Dr. W. Neff, Tel.: -142 [email protected]

Fraunhofer ILT Annual Report 2006 55 EUV microscopy for defect inspection on surfaces and thin films

This increases the contrast and sensiti- Task vity of the system, enabling it to detect very small defects. Microscopes using extreme ultraviolet light are capable of detecting all types of defects on a scale of magnitude down to several tens of nanometers, Results and Applications because of the short wavelength and λ =13.5 nm the highly efficient interaction with The top illustration shows the dark- matter. Many applications, such as the field image of a cluster of spherical na- mapping of EUV masks for EUV litho- noparticles made of polystyrene latex, graphy, require an ability to scan large with a diameter of 112 nm, on a film surfaces for the presence of small prin- of silicon nitride with a thickness of table defects as rapidly as possible. The 150 nm, taken using the EUV transmis- technique of scattered-light measure- sion microscope at the Fraunhofer ILT ment in the EUV region is well suited in cooperation with the Chair of Optical for this purpose. Through the use Systems Technologies TOS at RWTH 60 x 80 Pixels of an optical system that both collects Aachen. A defect scan at 0.1 mJ/cm2 and images light, for instance a on the surface (single-pulse mode) was Schwarzschild objective in dark field successfully demonstrated. The scann- mode, and a detector that is sensitive ing rate is limited by the readout time to EUV light, it is possible to obtain and the size of the CCD. If transferred

s additional information on the position to applications such as mask-blank or t c

, and size of the defects. The method’s wafer inspection, this corresponds to a y t

i 2

s feasibility has been demonstrated maximum scanning rate of 3 cm /hour. n e

t using the existing laboratory EUV mi- n I croscope by means of experiments on When the system is used to measure test structures with bright-field and particles, it is possible to derive the in- dark-field illumination. The apparatus tensity of the scattered light from the Number of pixels was characterized with a view to known variables: detector sensitivity, establishing design parameters and intensity of the incident light, and the Above: Dark-field image the main characteristics of a system transmission of the optical system. of a cluster of spherical nano- particles at 13.5 nm. for commercial instruments. Comparing this result with calculations Middle: Line scan along the performed using the Mie theory, which white line in the image above. provides an exact description of the Below: EUV transmission mi- croscope at the Fraunhofer ILT. light scattered by spherical particles, Method enables not only the size but also the refractive index (and hence the mate- The EUV microscope developed at the rial) of the light-scattering particles to Fraunhofer ILT, consisting of a xenon be determined. gas-discharge source, grazing-incidence collector, sample positioner, multilayer- coated Schwarzschild objective, and EUV-CCD, was adapted for use in Contact dark-field mode. A zero-order dia- phragm placed in front of the objective Dr. L. Juschkin, Tel.: -313 protects the optical path against the [email protected] incidence of direct light, ensuring that Dr. W. Neff, Tel.: -142 only the light scattered by surface de- [email protected] fects (e.g. particles on the surface of a Prof. Dr. P. Loosen, Tel.: -162 thin film) will be collected and imaged. [email protected]

56 Fraunhofer ILT Annual Report 2006 Energy monitor for extreme ultraviolet radiation

the same time and at the same relative Task angle to the beam source. The repro- ducibility of the results is better than 1%. Compact, easy-to-operate devices for monitoring extreme ultraviolet radiation Because the reflectivity of the multilayer are indispensable to the development mirror varies as a function of the angle of beam sources operating in this re- of incidence, it must be ensured that gion of the spectrum. The activity of the optical axis of the energy monitor greatest interest today, that of deve- is perfectly aligned with the beam loping sources for extreme ultraviolet source. Repeated measurements of the lithography, calls for energy detectors emission spectra of tin and xenon re- capable of monitoring the photon flow vealed that an angular misalignment within a limited spectral bandwidth of approximately 1 degree could be of 2% or 0.27 nm with a center wave- regarded as the tolerance limit when length of 13.5 nm. aiming to achieve an accuracy of better than 2%, which as a general rule is automatically ensured by the mechani- cal design of the vacuum system. Method Energy monitor for emissions in the region of 13.5 nm. An energy monitor of the described type was built and tested as part of Results and Applications the Fraunhofer ILT’s joint development work on high-power sources for EUV The energy monitor has a length of lithography, conducted in partnership 22 cm and is connected to the source’s with Philips. The monitor is based on vacuum system by means of a CF40 an off-the-shelf photodiode coated flange. A center wavelength of 13.5 with a material that filters out wave- nm is produced at a spectral band- lengths above the extreme ultraviolet width of 0.27 nm. The signals are read range. The diode is connected to a out via a 50 Ω oscilloscope input. The spectral filter consisting of two multi- minimum pulse duration is determined layer mirrors, which have the necessary by the diode and lies in the region bandwidth of 2% and are thus ideally of 2 µs. The typical signal amplitude suited for simulating the spectral trans- is 30 mV/(mJ sr) when the monitor is mission characteristic of optical systems placed at a distance of 70 cm from used in EUV lithography. The signal the source. emitted by the diode can be read out directly on an oscilloscope connected to the monitor by a BNC cable. Contact The energy monitors are calibrated at the Fraunhofer ILT with reference to a Dr. K. Bergmann, Tel.: -302 known standard whose characteristics [email protected] have been defined by a recognized Dr. W. Neff, Tel.: -142 metrology institute such as the Physi- [email protected] kalisch-Technische Bundesanstalt (PTB) in Berlin. Calibration is performed using a compact pulsed source to which both energy monitors are connected at

Fraunhofer ILT Annual Report 2006 57 Simulation of laser-induced vacuum discharge

Lorentz force accelerates the plasma Task towards the axis of symmetry and the cathode (middle image left). The two Extreme ultraviolet (EUV) radiation is opposing flows form a stagnant zone generated with a vacuum arc ignited on the axis of symmetry containing a by laser-induced ablation of the cathode density maximum (top image left). The surface. The radiant power of the laser current distribution exhibits its highest creates a plasma, which propagates to values at the surface of cathode and the anode. When the plasma touches anode respectively (bottom image left). the surface of the anode, electrical The zone producing the highest EUV discharge begins. This heats the plas- emissions corresponds to the zone ma to the point of emitting EUV radia- with the highest electron density, tion. As well as being dependent on which is found in the vicinity of the the laser parameters, the radiation cathode. This result has been validated characteristic is determined by the experimentally. current distribution in the plasma. The plasma variables and the current density are calculated. Contact

Dr. M. Aden, Tel.: -469 Method [email protected] Prof. Dr. W. Schulz, Tel.: -204 Maxwell equations were implemented [email protected] for the two-dimensional plasma model developed the year before. A cathode drop model was produced for the transition between the plasma and the cathode and integrated in the plasma model. The new model can be used to calculate the electromagnetic variables as a function of time and space, in ad- dition to the plasma variables.

Results and Applications

The electron density, current density and velocity field were calculated for the instant of maximum current Above: Electron density at (approx. 12 kA). The greatest electron the instant of maximum current between cathode (0) and density is found at the surface of the anode (d). cathode (0) (top image left). Middle: Velocity field at the instant of maximum current. Below: Current density at the As a result of the pressure gradient, instant of maximum current. the plasma velocity increases towards the anode. The Lorentz force inhibits radial expansion, obliging the distribu- tion to spread chiefly along the axis of symmetry (0-d). At the anode (d), the

58 Fraunhofer ILT Annual Report 2006 Laser Material Processing Business Area Laser Material Processing

Production processes addressed by this business area include cutting and joining techniques applying micro- and macro-technology, as well as surface engineering. The services provided extend from process development for the manufacture of sector-specific products and the integration of these processes in production lines, through simulation services for laser applications, to the production of samples in sup- port of series production start-up. The strength of the business area is rooted in its extensive process know-how, which is tailored to specific customer requirements in each case. In addition to process development, the business area offers complete system solutions which utilize selected technology net- works. Customers are offered laser- specific solutions that encompass design engineering, material specification, Mold cores of an injection product design, production equipment molding tool. Left: Blank, right: Finish-machined part. and quality assurance. In addition to the target market of material process- ing, the business area also addresses customers in the medical engineering, biotechnology and chemical sectors.

60 Fraunhofer ILT Annual Report 2006 Contents

Überschrift

High-speed cutting with Generative production Sub-wavelength ripples: Forming fiber lasers 62 of microcoolers 76 periodic nanostructures by fs-laser radiation 89 Remote cutting of sheet metal 63 Manufacturing of ceramic components by selective laser Laser-assisted punching 90 Welding of electric contacts melting 77 for high peak currents 64 Laser-based solar cell technology 91 Computational steering

CO2 laser MAG hybrid welding system for parallelized Drill holes with a high aspect ratio 92 for wall thicknesses up to 30 mm 65 simulation calculations 78 Drilling and cutting High-speed welding of steels Process control in microwelding 79 of contoured holes 93 using fiber lasers 66 Detection of process faults Offline determination of Integrated production of tailored in micro-spot-welding 80 workpiece-penetration during blanks using the combi-head 67 percussion drilling 94 Development of a miniaturized Combi processing with fiber scanner system for laser-beam Efficient expulsion of melt diameters of 50 and 600 µm 68 microjoining 81 during laser percussion drilling 95

Laser post-treatment of ceramic Microwelding of plastics Effective ray tracing for multiple coatings 69 by fiber laser 82 reflections during laser cutting and drilling 96 Surface melting of a single-crystal Laser welding of thermoplastics solidified nickel alloy for gas turbine without the addition of absorbers 83 High-speed microdrilling of components 70 transparent metal foils 97 Beam widening during laser Polishing of titanium welding of plastics: Determining Microdrilling of holes in by pulsed laser 71 the scattering coefficient of PA 66 84 pharmaceutical packaging for the validation of test equipment 98 Analysis of the flow-off Laser-assisted selective bonding behavior during laser cleaning 72 of similar and dissimilar classes Laser-diode-assisted transformation of brittle hard material 85 of plant cells 99 Process simulation for laser-beam structuring 73 Colored markings in glass 86 Temporally resolved quantitative phase microscopy 100 Graduated materials yield Product labeling with the aid improved characteristics 74 of nanostructures 87

Micro-laser-beam Manufacturing of waveguide deposition welding 75 lasers by pulsed laser deposition and fs-laser microstructuring 88

Note from Institute Director We would like to point out that the publication of the following industry projects has been coordinated with our customers. In principle, industry projects are subject to the strictest obligation to maintain secrecy. We would like to take this time to thank our industrial partners for their willingness to have their reports listed published.

Fraunhofer ILT Annual Report 2006 61 High-speed cutting with fiber lasers

Task Results and Applications

Up to an output of 4 kW (as at the We succeeded in producing cuts with end of 2006), the beam quality of fiber an excellent edge quality at extremely lasers is significantly higher than the high cutting speeds (v = 135 m/min best beam quality theoretically possible @ 4 kW, Rz = 6.6 µm). The numerical

for CO2 lasers. This means that, taken simulations and the experimental in conjunction with the better absorp- results were highly concordant. The tion of solid-state lasers over a wide simulation also shows that the maxi- range of parameters, fiber lasers can mum speeds attained are not far short achieve considerably better process of the theoretical limit that can be

efficiencies than CO2 lasers. In terms reached using diffraction-limited lasers of cutting processes, this is particularly with a corresponding power output. useful for handling thin sheet metals. The maximum speeds for different out- Speeds as high as these are of particu- puts were determined, using mild steel lar interest for linear applications such of 1 mm thickness as an example. as trimming or longitudinal and lateral splitting of strip material. Even profil- Cut edge of 1 mm mild steel, ing facilities with very high acceleration cut at 135 m/min (Rz = 6,6 µm, burr-free). rates can only realize these speeds Method when the contours are large enough. For 2-D and 3-D applications using lower The cutting tests were carried out speeds, the installed laser power can using a fiber laser with a maximum be reduced accordingly. Among the laser beam output of 4 kW and a fiber applications that benefit from these diameter of 50 µm. The beam para- developments is the cutting and trimm- meter product was 1.8 mm mrad. ing of deep-drawn components, par- ticularly those made of high-strength The focusing dimensions and the sett- materials that are difficult to handle ings for all other process parameters in mechanical cutting. Together with were adjusted to match the low thick- the excellent process efficiency of fiber ness of the metal sheet. lasers (approx. 25%), the method offers potential savings in terms of both invest- To make it possible to classify the ex- ment and operating costs. perimental results, the probable maxi- mum speed was calculated at the same time, using the CALCut simulation program. Contact

Dr. F. Schneider, Tel.: -426 [email protected] Dr. D. Petring, Tel.: -210 [email protected]

62 Fraunhofer ILT Annual Report 2006 Remote cutting of sheet metal

If this method is further optimized and Task developed to industrial maturity, the use of the scanner and the ability to The outstanding brilliance of modern dispense with the cutting head will fiber and disc lasers has the potential produce practical benefits due to the for developing processes which have simpler machining setup and the shorter not been able to be implemented until processing times that is possible to now. The task was to examine whether achieve as a result of the more dynamic the advantages of remote processing process. It will thus be possible to reach with scanners can also be used for high cutting speeds even in small radii, cutting metals. and the times between the cutting operations will be virtually negligible.

Method

Experiments were performed using a Contact fiber laser connected to a scanner. The useful power was limited to 1.5 kW Dr. F. Schneider, Tel.: -426 due to restrictions of the used scanner. [email protected] The tests were carried out on thin Dr. D. Petring, Tel.: -210 stainless steel sheets with thicknesses ≤ [email protected] 0.5 mm.

Results and Applications

The selected system configuration provides demonstrable proof of the feasibility of the remote cutting of metals.

In the present case, as in conventional cutting techniques, most of the material in the cut gap is ablated in its molten form. The physical process used to drive the melt out of the cut gap, even Above: Remote cutting without the driving force of a gas jet, of steels. is the vapor pressure gradient in the Below: Edge produced interaction zone. Since this effect is by remote cutting. promoted with increasing intensity, it is particularly important that the laser beams employed should be well fo- cusable. Recent progress in the output and beam quality of solid-state lasers offers promising prospects for the re- mote technique.

Fraunhofer ILT Annual Report 2006 63 Welding of electric contacts for high peak currents

Task Results and Applications

In the field of industrial electronics, With a welding time of 0.045 sec new ways of welding electric contacts for each contact, an adhesion width more cheaply and efficiently are being of more than 0.8 mm at the joining sought. section and a full penetration weld of the seam, the specified requirements In future, resistance welding will be for the welding process were fulfilled. replaced by laser beam welding as a means of joining tin-plated con- Laser welding of copper materials ductors. In contrast to the resistance holds attractive potential for develop- welding method, laser welding is ing sophisticated joining techniques distortion-free and has a shorter cycle for use in such fields as high-power time. There is no need for parts to be electronics, cooling technology and pressed together from two sides to solar thermal applications. create a welded joint; it is sufficient for the seam to be accessible from one side. Contact The welded seam must be capable of withstanding high peak currents V. Nazery Goneghany, Tel.: -159 of several multiples of 10 kA and [email protected] a mechanical shearing force of at least Dr. D. Petring, Tel.: -210 400 N. [email protected]

Cross-section through a weld in tin-plated copper at the lap joint. Method

In the context of a feasibility study, the process parameters were set in such a way that a full penetration weld of the seam with a joining width ≥ 0.8 mm was achieved with a laser output of approx. 3 kW.

The welds were produced using a fiber laser of high beam quality (1.8 mm mrad, maximum output 4 kW, fiber diameter 50 µm). The materials welded were copper alloys with a material thickness of 1.5 mm and 0.8 mm in the lap joint.

64 Fraunhofer ILT Annual Report 2006 CO2 laser MAG hybrid welding for wall thicknesses up to 30 mm

gations, large samples measuring Task 2,000 mm x 500 mm were prepared. Besides plate material, we also produced

In the shipbuilding industry, CO2 laser demonstrators such as joints of pipes MAG hybrid welding is a firmly estab- to plate flanges. Fine-grained structural lished technique for metal plates with steel of 30 mm thickness was laser wall thicknesses up to 15 mm. How- hybrid welded with satisfactory results, ever, there is a great need to further welding from both sides simultaneous- refine the technique so that it can also ly with two MAG power sources. In be used for wall thicknesses up to the thickness range up to 25 mm, we 30 mm. The goal of HYBLAS, a current were able to produce welds without European project funded by the RFCS, any hot cracks compliant with the is to develop process procedures for highest assessment group B of EN ISO laser hybrid welding of structural and 13919-1. fine-grained structural steels with yield strengths of up to 690 MPa and wall The advantages of laser MAG hybrid thicknesses up to 30 mm. welding are its high welding speed, low distortion, ability to bridge gaps, and the capability of single-pass weld- ing. Applications for these wall thick- Method nesses can be found in pipeline con- struction, shipbuilding, load-bearing

A Trumpf TLF 20000t CO2 laser and a structures, off-shore engineering, spe- Fronius TPS450 programmable welding cial constructions and in heavy vehicle power source were used for the tests. construction. The test welds were performed in the PA, PB and PC weld positions. To op- The work is being performed as part of timize the results, not only the laser the EU project »Economical and safe parameters and the wire feed, but also laser hybrid welding of structural steel a variety of weld preparations such as - HYBLAS«, which is sponsored by the V, Y, HY and DY welds with different Research Fund for Coal and Steel. included angles were examined. The welds were performed on butt, T and corner joints. Contact

Dipl.-Ing. N. Wolf, Tel.: -448 Results and Applications [email protected] Dr. D. Petring, Tel.: -210 For material thicknesses in the 15-25 [email protected] mm range, wide process windows in terms of the laser output and the gap were developed for MAG process con- figurations with leading or trailing wire feed, enabling high-quality welds to be performed. Using optimized para- Above: 25 mm laser-MAG meters, we achieved results such as hybrid weld, butt joint, vs = 0,6 the ability to bridge gaps of up to m/min, PL = 14.1 kW, PC position. 3 mm in a wall thickness of 15 mm. Below: Demonstrator compo- nent. In addition to the usual samples for mechanical and technological investi-

Fraunhofer ILT Annual Report 2006 65 High-speed welding of steels using fiber lasers

Task Results and Applications

For a steel material with a sheet thick- In the welding of thin metal sheets, ness of up to 3 mm, the maximum feed as in other materials processing tech- rates at which welding is possible with- niques, it can be observed that the out humping are to be determined. high beam quality of fiber lasers per- »Humping« is a term used to refer to a mits a significant increase in the pro- dynamic process in the weld pool that cessing speed. The speed at which occurs particularly at high welding the weld penetration limit is reached speeds, causing unwanted humps and is considerably higher than in compa-

deficiencies to form at periodic intervals rable test results using a CO2 laser. along the weld. By varying the parame- By adjusting the laser beam output, it ters, it is hoped to push the humping proved possible to raise the threshold threshold to speeds as high as possible. at which the humping effect occurs to speeds of up to 40 m/min (sheet thick- ness 0.6 mm), an important considera- tion for the customer. The welding Method results were excellent.

A 4 kW fiber laser with a fiber diameter Optimizing measures, such as specially of 50 µm was used for the tests. The shaping or directing the beam, were sheet thickness, the laser output and not used in this experiment and will in the welding speed were varied within future produce even higher boundary a certain experimental matrix in order speeds that are of great interest to to determine the weld penetration industry, particularly for use on long,

Weld cross-section at a welding limits and the threshold below which linear welds. speed of 18 m/min below the the process can be performed without humping threshold (sheet thick- humping. ness 1.6 mm, laser beam output 2 kW). The high beam quality helps to comply Contact with the requirement for narrow welds. Dr. F. Schneider, Tel.: -426 [email protected] Dr. D. Petring, Tel.: -210 [email protected]

66 Fraunhofer ILT Annual Report 2006 Integrated production of tailored blanks using the combi-head

Task Results and Applications

Particularly in the production of non- The integrated manufacturing process linear tailored blanks, lack of precision was demonstrated to produce non- causes gaps to form between the edges linear cuts and welds of very high quality. being joined. This makes it all the more It is particularly worth noting that the important to trace the weld accurately. welding line can be located without a Integrated cutting and welding with the weld tracking system because the precise combi-head opens up new possibilities position of the weld is known to the in this context. machine coordinate system from the laser cut that precedes it. The combi-head is software-controlled and can switch rapidly between the la- After welding, drill-holes, contoured ser-beam cutting and welding processes cutouts or edge cuts can be performed without any need to adjust the tool it- on the metal sheets while clamped in self. the same position. This option further enhances manufacturing flexibility and the number of different variations that can economically be produced. These Method subsequent cutouts can even be made across the weld itself, resulting in a Demonstration blanks with small di- high-precision component. mensions are prepared with the aid of an off-the-shelf combi-head based on The integrated production of tailored the Fraunhofer ILT demonstrator. Inte- blanks is an attractive alternative in the grated focusing optics and a z-axis for manufacture of small and mid-sized distance control enable it to meet the batches in view of the fact that signi- demands of industrial operation. A fiber ficant progress has been achieved, laser with a process fiber diameter of particularly in terms of the processing 100 µm is employed as the beam source. speeds for cutting thin metal sheets, not least as a result of the meanwhile

The joining edges of the two blanks are excellent beam quality of CO2 and solid- first prepared with two laser cuts, then state lasers. immediately welded along the identical path within the same clamping device. To conclude the process, two elongated holes positioned exactly to one another Contact are cut out. Dr. F. Schneider, Tel.: -426 The blanks are made from two differ- [email protected] ently galvanized car body materials with Dr. D. Petring, Tel.: -210 thicknesses of 1.0 and 1.2 mm. [email protected]

Cutting of joining edges followed immediately by welding.

Fraunhofer ILT Annual Report 2006 67 Combi processing with fiber diameters of 50 and 600 µm

Task Results and Applications

Materials processing with solid-state Just as in specialized cutting and weld- lasers can be subject to distinctly diffe- ing applications, it was found that rent focusing conditions, depending high welding and cutting speeds, in on the beam source employed. For some cases up to a factor of 2 higher example, the beam quality of lamp- than the standard values so far, can pumped rod lasers with a fiber diame- also be achieved in combi processing ter of 600 µm, which are still extremely using the small fiber diameter of 50 µm widespread, is inferior by a factor of and the good beam quality associated more than 10 to that of state-of-the- with it. In other words, narrow welds art fiber lasers with a fiber diameter with a high depth of penetration can of 50 µm. A comparative investigation be produced. was performed to find out what effect the use of such widely varying fiber However, combi processing particularly diameters has on combi processing in benefits from the narrow caustic that particular. can be produced with the 50 µm fiber because the window within which the desired weld shape and penetration can be adjusted by defocusing is sig- Method nificantly larger than when using a lesser beam quality. The nozzle spacing Spatial distribution of the Meaningful system and process para- during welding, which may thus vary isophots at the focus of a fiber meters were defined for the purposes within a correspondingly wide range, laser (left) and of a conventional Nd:YAG laser (right) under the of the comparison and had to be ob- has very little influence on the process. focusing conditions defined by served in all tests using the two fiber the process parameters. diameters of 50 and 600 µm. They The experiments revealed viable para- included Rayleigh length ≥ 2 mm, F meter windows for combi processing number ≥ 5, laser beam output 4 kW, also with lamp-pumped lasers. How- nozzle spacing for cutting 1 mm, ever, greater flexibility and a broader nozzle spacing for welding ≥ 6 mm, spectrum of applications in terms working distance for optics ≥ 200 mm, of speed, quality, ways of shaping processing speed 5 m/min. the weld, etc., can be achieved when using more modern beam sources such The process windows for the focus as fiber or disk lasers. position and nozzle spacing are smaller for cutting than for welding. The sett- ings used for cutting are therefore taken as a starting point for deter- Contact mining the scope available for welding in terms of weld penetration and Dr. F. Schneider, Tel.: -426 shaping at different nozzle distances. [email protected] Dr. D. Petring, Tel.: -210 [email protected]

68 Fraunhofer ILT Annual Report 2006 Laser post-treatment of ceramic coatings

Task Results and Applications

Thermal spray ceramic coatings have The Cr3C2-NiCr coating was surface- excellent wear-resistance properties. In melted to a melt depth of up to 20 µm corrosive environments, however, they when processed at room temperature. can only be used to a limited extent However, it was not possible to pre- owing to their residual porosity (upper vent the formation of cracks in the figure). This project sets out to increase melted surface layer, no matter which the corrosion-resistance of ceramic parameters were used. coatings by laser surface melting of a Cr3C2-NiCr coating. A recurring The lower figure shows a cross-section problem in the laser treatment of the of a Cr3C2-NiCr coating after laser Cr3C2-NiCr coating is the formation treatment. A crack-free surface layer of cracks due to the high brittleness of was achieved by carefully selecting the ceramic materials. process parameters especially the pre- heating temperature so as to reduce 10 µm thermal stress. The melt depth was 25 µm. Method One potentially interesting industrial The process parameters were deter- application of thermal sprayed Cr3C2- mined using flat samples made of du- NiCr coatings would be for the plex steel. The thickness of the duplex functional surfaces of high-pressure steel substrate was 5 mm and the pumps for seawater desalination. thickness of the Cr3C2-NiCr film was 70 µm to 90 µm. A Nd:YAG laser with a beam diameter of 400 µm was em- 100 µm ployed. The preheating temperature, Contact the laser output power, the feed rate Above: SEM image of the and the trace offset were varied. Dipl.-Ing. D. Maischner, Tel.: -361 surface of an untreated Cr3C2- [email protected] NiCr coating. Dr. K. Wissenbach, Tel.: -147 Below: OM image of the [email protected] cross-section of a Cr3C2-NiCr coating after laser treatment.

Fraunhofer ILT Annual Report 2006 69 Surface melting of a single-crystal solidified nickel alloy for gas turbine components

Task Results and Applications

The aim of the investigation is to de- The selection of suitable process para- velop a remelting process for repairing meters enabled a remelt zone with a damaged areas of single-crystal solidi- single-crystal structure to be produced. fied alloy turbine blades with a single- Subsequently, an area of the surface crystal solidified material. Cracks in the was remelted using an overlapping platform, the radius or the blade of strategy. A further positive outcome the gas turbine blade are removed by of the project was the implementation remelting whilst retaining the single- of a special process control system crystal structure. The remelted areas which made it possible to achieve a must be free of pores and cracks, and remelt of a depth relevant to turbine exhibit homogenous dendritic growth blade repairs. along the whole length of the layer. On the basis of these results, laser 1000 µm surface melting is to be tested on other sample geometries and on whole Method turbine blades.

2000 µm First of all, a suitable set of equipment with a laser beam source, optics and handling system is prepared. The sup- Contact Above: Cross-section of a melted track with a single- ply of inert gas to prevent oxidation re- crystal structure. presents a special challenge. To protect Dipl.-Ing. Bernd Burbaum, Tel.: -535 Below: Cross-section of two the surface from oxidation, the flat test [email protected] overlapping tracks with a single- pieces are remelted in a processing Dipl.-Ing. Torsten Jambor, Tel.: -193 crystal structure. chamber flooded with the inert gas [email protected] argon. In the first step, the remelt pro- Dr. Konrad Wissenbach, Tel.: -147 perties - remelt depth, remelt width [email protected] and dendritic growth - are examined as a function of the process parame- ters, e.g. laser output power, beam geometry and feed rate, in order to determine the most suitable parame- ters. The laser remelting process is per- formed on flat test pieces.

70 Fraunhofer ILT Annual Report 2006 Polishing of titanium by pulsed laser

Task Results and Applications

The polishing of titanium and titanium The roughness of milled titanium sur- alloys such as TiAl6V4 is a work-inten- faces can currently be reduced from sive process when using conventional Ra = 0.25 µm to Ra = 0.08 µm. The machining techniques, because the processing time in this case is of 3.3 material tends to 'smear' under con- s/cm2. tact with mechanical tools. As part of a project called 'LaserFinish', researchers Conventional grinding and polishing are investigating the use of a pulsed la- processes can result in scoring, and ser to polish titanium parts. Such parts subsequent grinding steps can produce are intended for applications in human 'smeared-over' surface defects. Rem- medicine, in the fabrication of blood- nants of the grinding agent, bacteria conducting implants. The main require- and other impurities can then cling to ments for the surface of these compo- these defective areas. During laser po- nents are that it should: lishing, the surface solidifies from the • reduce the friction between blood molten state. Sharp-edged scratches, constituents and the surface, to smeared-over grinding ridges and un- Above: Titanium implants, minimize or prevent damage to the dercuts do not occur. When examined right: initial state, left: polished blood. under a microscope, the surface is thus with a laser. • prevent blood constituents from free of defects and offers a high level Middle: Initial state, milled. Below: Polished with a laser. adhering to the surface, to prevent of biocompatibility. thrombosis. Divided into 11 subareas, the entire geometry of a titanium part was po- lished in 2 minutes. No borders are visible Method between the consecutively polished subareas, for example between the By performing tests on flat samples, wing and the cylinder. The next step is the researchers established suitable for the project partner to characterize process parameters for laser-polishing the properties of the laser-polished of the titanium material TiAl6V4. Pro- surfaces and finished parts in greater cessing strategies were developed for detail. polishing complete three-dimensional parts, and their geometry was pro- grammed. The surfaces were analyzed by means of white-light interferometry, Contact light microscopy and scanning electron 50 µm microscopy. Functional testing of the Dipl.-Ing. S. Hack, Tel.: -299 parts is being carried out by the project [email protected] partner. Dr. E. Willenborg, Tel.: -213 [email protected] Dr. K. Wissenbach, Tel.: -147 [email protected]

50 µm

Fraunhofer ILT Annual Report 2006 71 Analysis of the flow-off behavior during laser cleaning

in a single plane with a depth of approx. Task 1 mm. By analyzing individual frames and image sequences, quantitative Laser cleaning is an ablative process conclusions can be drawn regarding which generates ablated products in the main flow-off direction as well as the form of gases and particles. It is the speed and direction of individual important that these ablated products particles under various test conditions. are collected thoroughly by means of an adapted suction technique to ensure high process efficiency, a high surface cleanliness, compliance with Results and Applications workplace health and safety regula- tions, and adequate protection of the Without suction (top image left), the laser optics against soiling. To achieve dominant flow-off direction is almost high ablation rates, the tendency is to perpendicular to the surface. The laser use increased laser outputs (> 500 W), light interacts with the ablated pro- particularly when cleaning with Q- ducts over a considerable distance, switched Nd:YAG lasers. This intensifies resulting in poor process efficiency. the problem of collecting the ablated The particles reach a velocity of up to products, as these accumulate in in- 90 m/s. By finding a more suitable po- creasingly large amounts per given time sition for the suction nozzle relative to period. The goal is thus to develop the incident laser light (bottom image suitable methods of analyzing the left), this interaction is reduced and the flow-off behavior of the material during ablated products are almost fully collec- laser cleaning, such that the collection ted. This not only helps to improve rate may be increased by means of a process efficiency but also to prevent suitable suction technique and with the lens system from becoming soiled. the help of optimized nozzle geome- tries and arrangements. The next step is to automate the extremely time-consuming manual analysis of the image sequences.

Method

In order to analyze the highly dynamic Contact flow-off processes taking place, the re- searchers set-up a visualization system Dipl.-Phys. C. Johnigk, Tel.: -301 based on a high-speed video camera [email protected] (4,500 frames/s). The illumination and Dr. K. Wissenbach, Tel.: -147 filter systems employed must fulfill [email protected] special requirements in order to filter out light emitted by the process. A diode laser combined with a band-pass filter has proven to be a suitable option. The laser beam is shaped in such a way that a kind of 'light section' is genera- Above: Free flow-off without suction. ted in the observation plane, allowing Below: Ablation process with the flow-off behavior to be monitored suitably positioned suction nozzle.

72 Fraunhofer ILT Annual Report 2006 Process simulation for laser-beam structuring

For this purpose, a model was created Task which takes into account the pressure balance equation for calculating the In addition to structure and chemical geometry of the melt surface, a balance composition, the topography of a sur- equation for the melt volume and the face has a significant bearing on its coupling between deformation of the functional properties. melt surface and the kinematics of the three-phase line along the solidification A completely new technique for the front. structuring of surfaces is that of laser- beam remelting. By combining this technique with the laser polishing me- thod developed at the Fraunhofer ILT, Results and Applications which is also a remelting process, it is possible to achieve significant synergy The comparison with experimental effects, as surfaces can be simulta- results for single tracks shows a good neously polished and structured in a concordance with regard to the result- single process step (figure top left). ing surface topography (figure bottom left). The surface structure was produced The surface is structured by redistri- by harmonically modulating the laser buting the material in its molten state. output power. The model will be used The topography obtained results from to determine the cause-and-effect re- the kinematics of the three-phase line, lationship between the process para- which can be influenced, for example, meters and the resulting surface topo- by modulating the laser output power. graphy, and will thus help to establish In mathematical terms, surface melting the process limits, initially for single with laser radiation can be represented tracks. In addition, the model will be as a free boundary value problem. An expanded in order to calculate which in-depth understanding of the process kind of surface structures can be gene- is being developed on the basis of a rated by overlap processing of single self-consistent numerical solution, in tracks. order to derive the information requi- red to improve process layout.

Contact Above: Topography of a steel surface (15 * 15 mm2) structured Method Dr. N. Pirch, Tel.: -403 and polished with a laser. [email protected] Below: Comparison of the surface topography of a single A solution to the free boundary value Dr. K. Wissenbach, Tel.: -147 track, experimental (above) problem comprises the self-consistent [email protected] and calculated (below), in a reciprocally coupled calculation of tem- 3-D isopleth diagram perature distribution and Marangoni flow, and the dynamic of the free phase transformation interface and the melt surface, which is important for surface topography formation.

Fraunhofer ILT Annual Report 2006 73 Graduated materials yield improved characteristics

Task Results and Applications

The manufacturers of injection-molding Injection mold cores have to quickly and die-casting tools are seeking to conduct the heat away from the plastic develop products which will meet in- in order to keep the cycle time down creasingly complex requirements and and to ensure good demoldability. provide improved functional properties. Copper fulfills the requirements in this In many cases these aims cannot be respect but its resistance to wear and achieved with a single, homogeneous corrosion is inadequate for most ap- material. A solution to this problem plications. The top figure shows the is offered by graduated materials in blank and a finish-machined mold core which various properties, such as which has been coated with a gradua- corrosion and wear resistance or ted layer on a steel basis. Field tests toughness and strength, are combined show that this mold core cools more through variation of the chemical com- quickly after the injection operation position. compared with mold cores made of tool steel, and as a result demoldability The objective is to harmonize the pro- is improved. The gradient coating en- perties in such a way that tool life is sures wear resistance on a par with increased and cycle times for the pro- tool steel. The bottom figure shows a duction of plastic or aluminum compo- graduated tool insert for a die-casting nents are reduced. mold, produced by a means of laser generation. The core is made of tough 20 mm stainless steel and the enclosure con- sists of a wear- and corrosion-resistant Method steel alloy. The aim is to reduce the risk of heat cracking by combining Two different approaches are being toughness and strength in the volume pursued for the manufacture of of the mold. The tool inserts are cur- gradient layers: rently being tested. • Laser-beam deposition welding of gradient layers on a blank. • Laser-beam generation of complete tool inserts which have a graduated Contact structure. Dr. A. Weisheit, Tel.: -403 [email protected] Dr. K. Wissenbach, Tel.: -147 15 mm [email protected]

Above: Mold cores of an injection molding tool. Left: Blank, right: Finish- machined part. Below: Laser-generated tool insert.

74 Fraunhofer ILT Annual Report 2006 Micro-laser-beam deposition welding

Task Results and Applications

Process techniques are being developed Powder-focus diameters of < 200 µm for laser-beam deposition welding can be achieved using the adapted using powder filler material which will coaxial nozzle, which improves the make it possible to produce structure powder inflow efficiency compared sizes of < 100 µm. With precise ma- with conventional powder infeed terial deposition, the surfaces of micro- nozzles by a factor of 2. By using components will be repaired by depo- metal powders with particle diameters sition of similar material or selectively of < 20 µm, structure resolution can be modified (coating, dispersion) by de- refined by a factor of 3 to 5 compared position of dissimilar material. With with the state of the art. By way of selected parameters 2-D and 3-D example, the top picture shows a single functional surfaces are being produced track of 316L with a track width of on components from the tool and die, about 45 µm and a track height of electrical and medical device sectors. 10 µm. Surface coatings can be pro- 50 µm The repaired or modified surfaces duced by juxtaposing single tracks are being tested and assessed by the (middle and bottom figures). The project partners in respect of their pro- coating consists of 20 individual tracks cessability and functional properties. and has a coating height of 10 µm.

Method Contact

To achieve the required structural sizes, Dipl.-Ing. T. Jambor, Tel.: -193 continuous-wave fiber lasers and [email protected] 100 µm pulsed Nd:YAG lasers are used. The Dr. K. Wissenbach, Tel.: -147 powder gas system is being further [email protected] developed to deliver filler powders with grain fractions of < 20 µm. The aim is to increase the efficiency of the powder inflow by adapting existing coaxial nozzles. The impact of the pro- cess parameters including laser power, beam diameter, feed rate, powder mass flow and powder particle size on the welding result is being examined in experimental investigations.

Fundamental studies are being con- Above: Micrograph of a single track of 316L on stainless steel. ducted with the filler materials 1.2343 Middle: Micrograph of a and 316L on steel. In parallel, para- coating created by 20 individual meter windows for nickel-based and tracks of 316L on stainless steel. Below: Surface topography of a cobalt-based alloys, titanium, gold and coating created by 20 individual silver are being determined. tracks of 316L on stainless steel.

Fraunhofer ILT Annual Report 2006 75 Generative production of microcoolers

Task Results and Applications

Diode laser bars are actively cooled By reducing the beam diameter and to remove the heat generated in laser adapting the process accordingly, the operation. The microchannel heat sinks smallest structure size (rib width) of used for this purpose are made of approx. 300 µm which can be produced copper and feature an internal water- using SLM can be reduced to approx. conducting microstructure. Unfortu- 100 µm, which is adequate for creating nately, the service life of the diode laser the inner microstructure for the micro- bars is often shortened because the channel heat sink. This means that heat sinks become corroded. For this SLM can be used to produce micro- reason, microchannel heat sinks made channel heat sinks with outer dimen- of corrosion-resistant material are re- sions of 1.2 mm x 12 mm x 26 mm quired. One approach in pursuit of this and an internal microstructure con- objective is to generatively produce sisting of water-conducting channels 1 mm them from a corrosion-resistant nickel with a width of 250 µm / 150 µm and alloy by means of Selective Laser Melt- ribs between the channels of 100 µm. ing (SLM). The aim is to make up for The powder remaining inside the mi- SEM image showing the micro- structure of a microchannel the lower thermal conductivity of the crostructure on completion of the pro- heat sink produced using SLM. Ni material compared with copper by cess can be removed without difficulty creating an inner microstructure which using compressed air. Depending is more effective in terms of heat on the geometry of the inner micro- transfer. This requires the development structure, the water throughflow rate of a SLM process to produce structure reaches 1.2 l/min at a pressure of sizes of approx. 100 µm. 1.5 bar. The SLM system can produce approx. 50 microchannel heat sinks with the above dimensions simulta- neously. Method

In SLM the size of the structure that can be produced is determined by the Contact diameter of the focused laser beam. Up to now, a diode-pumped solid-state Dr. W. Meiners, Tel.: -301 laser with a beam diameter in the fo- [email protected] cus of 200 µm has been used for the Dr. K. Wissenbach, Tel.: -147 SLM process. A fiber laser is now being [email protected] used to create microstructures. Thanks to the higher beam quality it is possi- ble to achieve a beam diameter in the focus of 70 µm while retaining the same optical conditions. The SLM pro- cess parameters are adapted to the re- duced beam diameter in such a way that the components produced exhibit a density of approx. 100 %. In addition, a suitable scanning strategy is being developed for the production of micro- structures.

76 Fraunhofer ILT Annual Report 2006 Manufacturing of ceramic components by selective laser melting

Task Results and Applications

The generative process of selective Using a zircon oxide (ZrO2)-based ma- laser melting makes it possible to terial, a very high component density produce complex three-dimensional of over 98%, i.e. an almost pore-free components very quickly layer by layer structure, is attained. The demonstration from a powder starting material. This components illustrated here exhibit process is already used in industry an accuracy of better than ± 0.2 mm to make many series-produced com- and a good surface finish (Rz < 60 µm). ponents from metallic materials. In principle, spinel (MgAl2O4) and

aluminum oxide (Al2O3) can also be At the Fraunhofer ILT, work is being processed by laser melting. On all the conducted on the further development materials used up to now, however, of selective laser melting for processing fine structural cracks can be observed ceramic materials. The aim is to deve- which limit the material’s strength. lop a process by which components One way of solving this crack problem 10 mm made of high-strength oxide ceramic is to preheat the basic platform and to can be produced generatively with heat the component during the entire great accuracy. process in order to reduce thermally in- duced stresses. Preheating temperatures of up to 900 °C have already been achieved and a device which will pro- Method duce distinctly higher temperatures is currently being developed. The subse- Various approaches are being pursued, quent glass infiltration of the ceramic including direct melting of ceramic bodies produced is also being examined powder, a reaction-sintering method as an alternative. 5 µm and a technique in which a composite ceramic and glass material is processed One potential application is e.g. the Above: Demonstration com- by laser melting. The first approach production of shell moulds for precision ponent of ZrO2-based ceramic mentioned, which focuses on the casting. As soon as an adequate produced by selective laser complete melting of purely ceramic strength can be attained, the produc- melting. powder, is delivering promising results. tion of fully ceramic dentures, e.g. Below: Demonstrator for a fully ceramic dental restoration By using flexibly modified test facilities of zircon oxide ceramic, will be an in- of ZrO2-based ceramic. in combination with various laser-beam teresting application. sources, the technology is being adap- ted to the specific requirements of ce- ramic materials. Contact

Dipl.-Ing. J. Wilkes, Tel.: -361 [email protected] Dr. K. Wissenbach, Tel.: -147 [email protected]

Fraunhofer ILT Annual Report 2006 77 Computational steering system for parallelized simulation calculations

Task Results and Applications

Complex simulation calculations are The CS system is used to compute melt distributed over several high-perfor- flow and heat transfer. The complex mance computers. The calculation and simulation tasks are put together from the visualization of the results are con- existing and tested modules. With the trolled in real time by means of a com- developed computational steering sys- putational steering system (CSS). The tem, a tool is available for producing internal interfaces for communication new parallelized simulation programs with the graphical user interface (GUI) including visualization using already can be integrated in existing simula- existing modules. This procedure tions with little maintenance expense. shortens development times for new The CS system is designed in such a simulation programs and supports the way that the development time for analysis of variants in the model simulations with various model struc- structure. tures is shortened.

Above: GUI of the computational steering system for visualizing Contact temperature. Method Below: Flow diagram of the U. Jansen, Tel.: -163 computational steering system (CSS). CSS light blue, simulation The CS system uses a client-server [email protected] blue-gray, spawn light yellow. spawn architecture and communication Dr. M. Nießen, Tel.: -307 is handled by the message passing [email protected] interface (MPI). On the basis of this Prof. W. Schulz, Tel.: -204 architecture, the GUI (client) launches [email protected] simulations (server) which the spawn system connects with simulations that are already running. Control com- mands, e.g. for interrupting or termi- nating the simulation process and ex- changing parameter and calculation data, are implemented through a sui- table protocol. The protocol is encap- sulated in a dedicated library, which simplifies integration in existing pro- grams or the creation of new pro- grams. Data exchange with the GUI is conducted by means of associative arrays and functions along the same lines for various programs. Program control data and input masks for the parameters are created in XML format. As various visualizations are required for different simulations, these are based on plug-ins which use the visua- lization toolkit (VTK) based on OpenGL.

78 Fraunhofer ILT Annual Report 2006 Process control in microwelding

Task Results and Applications

With increasing product miniaturization, Using this system, it has been possible laser technology today plays an essen- to detect welding faults caused by tial role in the production of micro- a concealed gap in the lap weld. To engineered components and assemblies. this end, the size of the molten bath Rising quality requirements not only is continuously measured during the set higher and higher requirements welding process. By comparing the real gap size 100 µm for the process technology but also contour of the melt pool with an idea- l

o gap size 0 µm demand quality-assurance measures lized, circular contour, a specially deve- o p t l which ensure the reliable recognition loped algorithm permits robust, real- e of process faults. For this reason, post- time-enabled melt pool measurement m process inspections are frequently con- even if e.g. splashes occur. ducted. A 100-per-cent post-process process duration inspection as a rule entails considera- Because a gap in the joint can influ- ble time and effort, however, and so ence both the pressure conditions in it is often restricted to surface faults. the key hole as well as the thermal As a result, there is a need for reliable conduction conditions, irregularities online detection of welding faults by in the development of the melt pool means of in-process control. can be detected if such a gap occurs. Compared with conventional techniques, the method offers the advantage that the recognition of faults is based on Method physical effects and does not rely on comparing incoming signals with re- The camera-based system for coaxial ference values. As a result the system process control (CPC) developed by offers great flexibility and can be used 0,1 mm the Fraunhofer ILT makes it possible to in a wide range of applications. conduct locally resolved observation of microwelding processes with a time re- solution of up to 10 kHz. The key part of the system is a CMOS camera, with Contact which the welding process is observed coaxially to the laser beam by the op- Dipl.-Ing. J. Gedicke, Tel.: -145 tical processing system. Likewise by [email protected] means of coaxial illumination of the Dipl.-Ing. B. Regaard, Tel.: -320 workpiece surface, it is also possible [email protected] to detect the phase boundary between Dr. A. Gillner, Tel.: -148 0,1 mm solid and molten material with a diode [email protected] laser. This enables certain physical con- ditions which correlate with process Above: Development of the molten bath in the lap welding faults to be identified, e.g. in spot of stainless steel sheets with welding. and without a gap in the joint. Below: Measuring the molten bath by fitting a circular con- tour into the recognized molten bath geometry.

Fraunhofer ILT Annual Report 2006 79 Detection of process faults in micro-spot-welding

For detecting splatter, an algorithm Task has been developed which recognizes »dark« round objects on the surface Spot welding or spaced spot welding structure. By analyzing consecutive using pulsed laser radiation is an images the system can differentiate established process, especially in the between lying and flying splatter. electronics industry, for joining over- Restriction of the possible maximum lapping connections in series produc- and minimum splatter size and the tion. The high production volumes in area of measurement reduces the this sector (up to 108 p.a.) and the pseudo-fault rate. high requirements in respect of process capability (Cpk ≥1.67) call for efficient Inadequate fusion is detected by ana- and reliable methods of process con- lyzing the melt pool. Its size varies trol. The following major causes of during the weld as a function of the faults have been identified: gap between the joining partners; • lack of fusion causing contact therefore a missing connection can failures in electrical components. be detected by analyzing the increase • splatter which can lead to faulty of the melt pool (lower figure). contacts.

The aim is to provide monitoring systems for detecting such faults. Results and Applications

The techniques for recognizing lack of fusion and splatter can be deployed Method in spot welding applications where the beam is introduced vertically. So far, At the Fraunhofer ILT, a process obser- tests have been conducted on copper vation technique has been developed and steel materials up to a thickness of which uses a camera to monitor the 0.5 mm. The process is currently being externally illuminated workpiece sur- further developed for applications with face coaxially to the processing laser. scanner optics. With frame speeds of up to 7,000 images per second, the melt pool and splatter outside the molten zone can be observed (middle figure). Contact

Dipl.-Ing. B. Regaard, Tel.: -320 [email protected] Dipl.-Ing. J. Gedicke, Tel.: -145 [email protected] Above: Optical setup for the Dr. S. Kaierle, Tel.: -212 coaxial illumination and obser- [email protected] vation of the workpiece surface during laser welding. Middle: Image of a spot welding process with coaxial external illu- mination. Splashes are detected using image-processing algorithms. Below: Development of the size of the molten bath in a spot-weld- ing process. Melting takes place more slowly if the joining partners are not properly connected.

80 Fraunhofer ILT Annual Report 2006 Development of a miniaturized scanner system for laser-beam microjoining

Task Results and Applications

The use of fiber-guided laser beam As a first step, the complete optical sources of extremely high optical qua- system was designed using the ray lity in combination with miniaturized tracing method. Compared with already beam guidance and beam shaping developed miniaturized projection systems and tiny visual monitoring scanners, the laser power required for systems makes it possible for the first materials processing and the high reso- time to create laser beam-based gripp- lution in the 1 µm range along with a ing and joining systems integrated in high numeric aperture represent a par- conventional high-performance assem- ticular challenge. The integration of an bly units for packaging in electronics. external illumination source for camera- based process monitoring with a smaller In the DFG-funded Collaborative wavelength than the laser wavelength Research Centre 440 »Assembly of requires a chromatic adjustment of the Hybrid Microsystems«, a miniaturized complete optical system. The reduction scanner system with a size of a match- of the raw beam diameter at a minimal box is being produced which incorpo- focus diameter of up to 20 µm and rates innovative scanner mirrors. Be- a working range relevant for materials cause this system is distinctly smaller processing of 30 x 30 mm2 , as well than the systems currently available as a working distance of 50 mm, is a on the commercial market it can be decisive factor in the design of the op- integrated in highly dynamic assembly tical system. units.

Contact Method Dipl.-Ing. F. Schmitt, Tel.: -322 Above: Ray tracing of the Parameters are taken into account in [email protected] f-theta focusing optics. the design of the beam path which Dr. A. Gillner, Tel.: -148 Below: Size of a commercially result from miniaturization of the total [email protected] available scanner compared system. They include availability of mi- with the development target. niaturized optical systems, intensities on the scanner mirrors, and the beam guidance and shaping of various wave- lengths (VIS, NIR, IR). Also, the laser processes for welding metals and for welding plastics entail opposing require- ments for the system as a whole, such as imaging quality, intensities and focus geometry. The miniaturization of scanner systems for micromaterials processing is limited by the available optical coat- ings of the elements used and by the dimensions of the optical components. Minimal dimensions for usable raw beam diameters are the result.

Fraunhofer ILT Annual Report 2006 81 Microwelding of plastics by fiber laser

The application of an innovative irra- Task diation strategy for introducing the energy is required, as the intensity In recent years, laser-beam welding of the focused fiber laser beam of plastics has become an established (106 W/cm2) is much higher than the processing technique for many indus- usual values for plastics welding trial applications. It has limitations, (300 W/cm2). By using a highly dynamic however, with respect to weld seam rapid circular movement along the width and operating speed. New deve- direction of feed, welds can be made lopments in medical and biotechnolo- without destroying the material even gical microsystems have increased the at great intensities. requirements which have to be met in the laser welding of plastics. The widen- ing of the range of materials used in microsystems engineering to include Results and Applications plastics has both opened up new pro- 500 µm spects and created new requirements With the new irradiation strategy and for innovative concepts and methods use of the fiber laser, microfluidic com- that can be applied. ponents made of PMMA and PC can be sealed along the complex weld con- Production techniques are required tour with a laser output as low as 3.5 which will enable plastics to be reliably W and an operating speed of 2 m/min. welded at geometries of 100 µm. On The width of the weld seam is less the basis of a fiber laser and an inno- than 500 µm, and a cycle time of vative irradiation strategy, a new tech- below 6 s can be achieved with cor- nique has been developed for the laser responding scaling of the process para- welding of plastics. meters. On the polycarbonate samples, weld seams with a good visual appea- rance can be produced at an output of 8 W and a feed rate of 18 m/min. Above: Light-microscope image of two 120 µm-wide weld seams Method The weld seam width can be reduced on a sample of polycarbonate. to 100 µm. The new process has great Below: Welded microfluidic com- In the tests, a fiber laser with a wave- potential for use in the large-scale pro- ponent made of PMMA with a length of 1112 nm and a maximum duction of microfluidic components. complex channel structure. output of 9 W is used as the beam source. Thanks to its excellent beam quality of M2 < 1.1 a focus diameter of 30 µm can be attained for a working Contact distance of 100 mm. Dipl.-Ing. A. L. Boglea, Tel.: -217 [email protected] Dr. A. Gillner, Tel.: -148 [email protected]

82 Fraunhofer ILT Annual Report 2006 Laser welding of thermoplastics without the addition of absorbers

Task Results and Applications

Thermoplastic polymers usually exhibit By using innovative high-performance low absorption in the visible and near- laser-beam sources, it is possible for infrared region of the spectrum. In un- the first time to dispense with added modified condition, the plastics are op- pigments. Instead, the characteristics tically transparent or translucent. Laser- of the laser light are adapted to the beam transmission welding of these intrinsic absorption properties of the components entails the challenge of plastics. With suitable process control, ensuring by means of suitable pigmen- the advantages of transmission joining tation that the laser light is transmitted can be retained without influencing through the first of the two parts to be the surface of the plastic components joined and is absorbed in the second. facing the laser beam. Transparent plastics can also be welded in this way without using infrared absorbers. It must, however, be ensured that the Method greater part of the laser energy is con- verted into heat at the point where the At present, in the simplest case, a two plastic parts meet. transparent-black combination is crea- ted by admixing carbon black in the absorbing part. This addition of carbon black is not possible in cases where Contact the plastics have been colored using dyes or pigments, or when joining two Dipl.-Ing. M. Poggel, Tel.: -158 transparent plastics, as the carbon [email protected] black strongly influences the coloring Dr. A. Gillner, Tel.: -148 500 µm effect or transparency. In these cases, [email protected] an adequate level of absorption can be Above: Microfluidic component achieved by using either absorbent in- made of TROGAMID (PA PACM termediate layers or organic absorbers 12) with a meandering channel which are added to the absorbing part. structure. The absorbers have to be applied to Middle: Detail of channel branching. the component an additional process step and can influence the color effect of the parts to be joined.

Right: Transparent mini-housing. Foreground: Welded without using IR absorbers. Behind: Standard combination transparent/black.

Fraunhofer ILT Annual Report 2006 83 Beam widening during laser welding of plastics: Determining the scattering coefficient of PA 66

function of material thickness. An ex- Task ponential function is fitted to the mea- sured values and directly delivers the

During laser transmission welding of scattering coefficient µs. The scattering plastics, the laser beam widens as it coefficient thus obtained is unrelated passes through the upper of the two to the transmittance of the polymer, parts to be joined, provided that the as the measured beam diameters do other part is made of a semi-crystalline not vary as a function of the output. polymer (top image left). This has the effect of reducing the beam intensity in the weld zone and increasing the width of the weld seam. The phenomenon is Results and Applications well-known but has not been investi- gated previously. The scattering coefficient determined for PA 66 at a wavelength of 803 nm is 1.18 mm-1. This means that, accor- 50 µm ding to Method

Above: Transmitted light micro- scope image of a sample 10 µm A reliable expression of observations in thick made of semi-crystalline the field is that, when passing through polyamide 66. a polymer of thickness x, the intensity I the beam diameter d doubles in size Middle: Power density distribu- tion of an 803-nm diode laser (= power/surface area) of a laser beam after passing through PA 66 with a beam after passing through a is reduced according to an exponential thickness of x = 1.17 mm. 0.2-mm-thick PA 66 sample. Mea- function: sured beam diameter: 0.68 mm. With the components and processes Below: Same as middle image but with a sample thickness of described above, the Fraunhofer ILT 1.8 mm and a measured beam thus disposes of a test system for the diameter of 1.82 mm. where µa represents the loss of intensity qualification of materials during laser

resulting from absorption, and µs the welding of plastics. reduction in intensity caused by an in- crease in the beam diameter d. To de-

termine the value of µs for the material PA 66, samples of various thicknesses Contact were prepared, and the intensity distri- bution of a diode laser beam with a Dipl.-Phys. G. Otto, Tel.: -165 wavelength of 803 nm was recorded [email protected] with a CCD camera after the beam Dr. A. Gillner, Tel.: -148 had passed through the polymer mate- [email protected] rial (the laser output on the sample positioned directly in front of the CCD chip is approx. 40 mW after a 1:100 re- duction). For each intensity distribution, the beam diameter d is determined using the second-moment method, and the value 1/d2, which is propor- tional to the intensity, is plotted as a

84 Fraunhofer ILT Annual Report 2006 Laser-assisted selective bonding of similar and dissimilar classes of brittle hard material

Task Results and Applications

Hybrid microsystems often contain Selective laser bonding holds great po- discrete components made of different tential for application in the packaging materials, including glass, engineering of microsystems. It can be utilized at ceramics or single crystals such as wafer level as part of a bond station sapphire. These microsystems are often and used to fix or selectively bond sili- assembled on a silicon substrate which con and silicon, for example in micro- also contains the components of elec- electro-mechanical systems (MEMS), or tronic circuits. Commonly used me- silicon and glass, for instance in 'silicon thods for joining these components on insulator' (SOI) processes. The me- are silicon direct bonding or anodic thod of bonding similar classes of ma- bonding, both of which require bond- terials with absorbent intermediate la- ing of the entire surface. These joining yers can be used for packaging in the methods inflict a high thermal stress field of display technology. Minimizing on the components, and are relatively the extent of the heat-affected zone inflexible when it comes to bonding protects the functional metal and or- differently shaped surfaces. As an al- ganic films and electronic components ternative to these wide-area methods, in the immediate vicinity of the joining laser bonding helps to minimize the area. A set of promising first results heat-affected zone and the associated has been achieved in the bonding of warping by exact monitoring of the silicon and silicon. Good results have energy deposition. also been obtained for bonds between silicon and types of glass with diver- In addition to being able to join dissi- gent coefficients of thermal expansion, milar classes of material such as silicon such as silica and soda-lime glass. and glass, laser bonding can also be used to join similar materials. By using absorbent intermediate layers, the laser radiation is converted into heat Contact energy at the joining interface. Dipl.-Ing. F. Sarı, Tel.: -358 [email protected] Dr. A. Gillner, Tel.: -148 Method [email protected]

Selective laser bonding is based on the process of transmission joining. One of the parts is transparent to the laser light, while the other is absor- bent. Most of the laser beam's energy Above: Silica-glass packaging on a silicon chip. is converted into heat at the joining Middle: Bond between glass interface, thereby heating the area of and glass. contact. Below: Fractured surface of a silicon sample, bonding of silicon and silicon.

Fraunhofer ILT Annual Report 2006 85 Colored markings in glass

Task Results and Applications

Markings in glass are used for a variety The glass is modified with ns-pulsed of purposes such as ornamentation, UV light emitted by a Q-switched, product markings on bottles, measur- frequency-tripled Nd:YAG laser (wave- ing instruments and medical devices, length 355 nm, pulse duration 10 to and even security codes. One technique 80 ns) and with fs-pulsed IR light emit- already available for this purpose is ted by a mode-coupled Ti:sapphire laser laser micro-marking. Such markings (wavelength 800 nm, pulse duration are permanent, inexpensive, and im- 100 fs) using differing pulse repetition possible to forge, but they are colorless rates, pulse energies and overlaps bet- (white). One technique for creating ween consecutive pulses. colored areas in glass is by forming nano- particles of metal (preferably silver). The soda lime silicate and borosilicate However, only yellow, red and brown glass materials, which are doped with shades can be obtained by this method. rare earth and transition metal ions, An added drawback of both processes are colored by the interaction with (laser micro-marking and the irradiation laser radiation. The laser radiation is of metal nanoparticles) is that they absorbed by optically and photochemi- build up considerable stress in the cally active polyvalent ions, and the glass, thus detracting from the stability optical energy produces fluorescence, and service life of the marked glass ionization and the formation of colored objects. areas. Depending on the selected laser emission parameters, such as wave- length and pulse duration, the glass is either tinted in the mass (linear ab- Method sorption, top image left) or volumetri- cally modified to contain 3-dimensional In order to produce colored markings markings (multi-photon absorption, Above: Violet-colored marking in soda lime silicate glass (3 x 3 x 1 cm3) without measurable mechanical da- bottom image left). Colored markings doped with V2VO5 and Ce2O3 pro- mage due to induced stresses, glass is can be produced in transparent and duced by linear absorption of ns- doped with special photochemically tinted glass as a function of the chemi- pulsed UV laser radiation. active ions. The introduced laser light cal composition of the glass and the Below: Yellow 3-D colored marking in soda lime silicate glass (3 x 3 x 1 cm3) is absorbed by these ions, causing local laser and process parameters. The doped with AgO3 produced by multi- coloration (ion coloration). If the laser shades that can be obtained are violet, photon absorption of fs-pulsed IR beam is focused in the right way, co- yellow and reddish-brown, each in laser radiation. lored markings can be etched in glass monochrome. The laser-induced color without generating the stresses that markings in the glass are reproducible, normally occur when conventional resistant to the effect of heat and ultra- laser methods are used. Suitable glass violet rays, and do not crack the glass. materials and laser light irradiation technologies are now being developed and tested. Contact

Dr. A. Horn, Tel.: -205 [email protected] Dr. I. Kelbassa, Tel.: -356 [email protected]

86 Fraunhofer ILT Annual Report 2006 Manufacturing of waveguide lasers by pulsed laser deposition and fs-laser microstructuring

5. Using imaging optics, the diode laser Task output is coupled into the resonator. The resonator mirror on the opposite The Fraunhofer Institute for Laser Tech- side is semi-reflecting and serves to out- nology is developing structured planar coupling the laser radiation. waveguide lasers, and has for the first time demonstrated laser activity in structured waveguides made of Laser spectrum Flourescence Nd:Ga5Gd3O12. Owing to their tailored Results and Applications geometry and large numerical aperture, planar structured waveguide lasers en- Deposition and structuring of the active able direct pumping with high-power film directly in front of the pump diode y t i s

n diode lasers. allows highly integrated laser sources e t n I to be mass-produced at a low cost.

Together with industry partners, the Method researchers are testing a variety of laser- Wavelength active materials for the generation of From process development to manu- defined wavelengths, especially in the facturing, the following steps were visible spectral range. carried out on the basis of customers' optical, thermal and geometric specifi- The flexibility offered by both processes cations: (pulsed laser deposition and structuring by fs-laser radiation) in terms of the ma- 1. The laser-active material is deposited terials to be processed is of particular as a 1 - 5-µm-thick film on lattice-com- advantage. patible crystalline substrates by means of pulsed laser deposition (PLD). Either crystalline or amorphous vitreous films can be produced as a function of the Contact

Above: Emission spectrum of an process parameters temperature and amorphous waveguide at pump light processing gas pressure. Dipl.-Phys. D. Wortmann, Tel.: -406 intensities below and above the laser [email protected] threshold of the waveguide laser. 2. The films are ablated locally using a Dr. J. Gottmann, Tel.: -406 Below: Waveguide laser consisting of a structured planar waveguide femtosecond laser to produce parallel [email protected] between resonator mirrors. grooves which define the width of the resulting planar waveguides. Featuring rectangular cross-sections, the wave- guides are tailored to the beam cross- sections of the broad-area diode lasers that serve as the pump source.

3. The length of the waveguides is re- duced to a few mm using a wafer saw and by lapping, and the end faces are polished to optical quality to minimize coupling losses.

4. Dielectric mirrors are applied to the end faces of the waveguides to form the resonator.

88 Fraunhofer ILT Annual Report 2006 Sub-wavelength ripples: Forming periodic nanostructures by fs-laser radiation

The ripples are coherently continued Task by application of numerous overlapping pulses. By moving the focus perpendi- Femtosecond lasers are capable of cularly to the laser polarization, two creating coherent periodic structures parallel ripples each with a width of (or ripples) on the surface of various about 125 nm and a typical depth of materials with a periodicity significant- 100 nm are produced at intervals ly below the wavelength of the laser of approximately 240 nm. radiation employed. Periodic ripples can also be coherently Potential applications include gratings continued in two dimensions by apply- ing multiple scans with a constant pa- Riffelabstand 240 nm for integrated optics and structured Fokus surfaces for biotechnical and engineer- rallel offset. ing applications.

Verfahrrichtung

Polarisationsrichtung Contact 1µm Results Dipl.-Phys. D. Wortmann, Tel.: -406 On the materials tested (dielectrics, [email protected] plastics, semiconductors and metals), Dr. J. Gottmann, Tel.: -406 ripples were produced at intervals [email protected] Riffelabstand equivalent to 25 - 75% of the wave- 240 nm length of the laser radiation employed. Polarisationsrichtung

The ripples are always aligned perpen- Verfahrrichtung dicularly to the polarization of the laser beam. Changes in the direction of tra- 1µm vel do not influence ripple orientation.

Verfahrrichtung

Polarisation

Above and middle: Ripples in fused silica. Single scan with polarization parallel to the direction of travel (above) und perpendicular to the direction of travel (middle); wavelength λ = 800 nm. Below: Coherent continuation of ripples in 2 dimensions on fused silica by application of multiple scans with a constant parallel offset of 400 nm.

Fraunhofer ILT Annual Report 2006 89 Laser-assisted punching

Task Results and Applications

As chipless manufacturing process, A prototype of the newly developed punching permits the short-cycle batch laser-assisted micro-punching system production of complex workpieces was tested on the magnesium alloy with near-optimum utilization of ma- AZ31. Sheet magnesium is very diffi- terials. At atmospheric temperature, cult to cut and form, resulting in fre- the cut surface consists of a smooth quent chipping on the cut surface at cutting zone and a fracture zone. The atmospheric temperature. This can be latter is characterized primarily by its avoided by heating the material. rough surface, which limits its use as a functional surface. By heating the Toothed wheels are now being pro- sheet metal material, the smooth cut duced which can be used, for instance, proportion can be increased to up to in micromotors and their transmission 100%, irrespective of the material and systems or as parts of mechanical move- process employed. ments. The selected wheel geometry features 36 teeth and a diameter of 5 mm. The sheet metal employed is 0.5 mm thick. During punching tests Method on magnesium, a completely straight cut was achieved. The laser technique enables the sheet metal to be heated quickly and con- Other applications can be envisaged trollably. The laser light emitted from in areas requiring high-quality compo- the fiber of a diode laser is guided nents with small structural features. By through the tool die onto the under- lowering the yield stress and activating side of the metal sheet via an array additional glide planes, it is possible to of optical elements. The radiant heat process high-strength and brittle mate- emitted by the metal is simultaneously rials. measured and used to control the process.

The tests were carried out on a hy- Contact draulic open-sided press with a pneu- matic feed. In addition to a punch, a Dipl.-Ing. J. Holtkamp, Tel.: -273 die and a clamp, the tool employed [email protected] consists of components used for inte- Dr. A. Gillner, Tel.: -148 200 µm grating the laser output and sensors [email protected] and for handling the punched-out parts. Above: Punching tool. Below: SEM image of 2 toothed wheels, hot-punched (above) The aim of this project is to create and cold-punched (below). adapted systems and tool engineering processes and, in particular, to master the insufficiently researched warm- forming process as well as the short- run manufacturing of components with microscale structural features.

90 Fraunhofer ILT Annual Report 2006 Laser-based solar cell technology

help of high-repetition laser beam Task sources and highly dynamic beam moving devices. For this purpose, the Photovoltaics is one of the key techno- researchers are implementing a fast logies that promise to assure tomorrow’s beam-guide system in combination supply of electricity, not only in Ger- with a suitable beam source as part many but also in many other countries of the project. At present, it is possible too. to produce 500 drill holes per second by means of a single-pulse drilling One of the pressing needs is to increase process. A suitable technique for the the efficiency of solar cells and solar electrical contacting of solar cells is modules, and to reduce reject rates that of laser-beam soldering, due to during manufacture. Paired with the the low and locally restricted energy demand for a dramatically increased input involved. By selecting suitable production volume, this calls for tech- solders, the joining temperature can be nologies that allow efficiency-optimized reduced to a minimum, and thanks to solar cells to be manufactured at rates the non-contact process, the solar cells of over 1000 Si wafers per hour, while are not subjected to mechanical strain, at the same time limiting the quantity unlike with conventionally used bow- of rejects to a minimum. In order to type electrodes. A further advantage meet these requirements, an internal of the laser-beam soldering process is Fraunhofer research project aims to that it can be automated. Instead of develop new technologies and de- the linear contact employed so far, the monstrate them to industry as inline cell connectors are linked to the solar solutions. On the one hand, these cell at 20 contact points. By suitably technologies aim to increase the effi- selecting the quantity of solder and ciency of solar cells and eliminate the the surface area to be irradiated, it is efficiency losses associated with con- possible to reproducibly set the elec- ventional manufacturing processes, trical transition resistance required. and at the same time they aim to im- prove the efficiency of the production process itself, thus lowering the rejec- tion rate. Contact

Dipl.-Ing. F. Schmitt, Tel.: -322 [email protected] Results and Applications Dipl.-Ing. A. Dohrn, Tel.: -220 [email protected] As a non-contact and selective tool, Dr. A. Gillner, Tel.: -148 the laser is predestined for use along [email protected] the entire process chain, from the silicon source material to the assembly of Eintritt Austritt complete solar modules, including va- rious production steps such as separa- tion, drilling, structuring and soldering. In the course of the project, two stages of the process chain are being tested and optimized at the Fraunhofer ILT. In Above: Laser-soldered cell the case of laser drilling, for example, connectors on a solar cell. Below: Hole matrix in silicon the goal is to achieve more than wafer. 25 µm 10,000 drill holes per second with the

Fraunhofer ILT Annual Report 2006 91 Drill holes with a high aspect ratio

Task Results and Applications

Deep drill holes with a small diameter In conventional percussion drilling can only be produced to a limited ex- (not superimposed) with a slab laser, tent by laser, and are therefore made closure of the drill hole temporarily using alternative methods such as halts the drilling progress and leads to electro discharge machining (EDM) considerable fluctuations in the time and electro chemical machining (ECM), required to achieve drill-through. which are time-consuming and thus expensive. The depth to which holes If the output of a DPSS laser is super- can be drilled by laser percussion drilling imposed on the beam, the drill-through is restricted by incomplete expulsion time is reduced for all material thick- of the molten metal from the base of nesses as the DPSS laser output increa- the drill hole and the resulting recast ses. The number and size of closures left inside the hole. When the melt occurring in the drill hole are also re- 0,5 mm sets, it closes off the bore hole (top duced. This results in a higher drilling image left). The goal is to overcome speed without changing the diameter these restrictions, which are due to of the drill hole. system-specific limitations of the laser systems employed, by time modulation The results show which temporal in- of the laser beam. The speed of the tensity curve is most efficient for drilling, drilling process and thus also the depth and can thus be used to develop active of the drill holes is to be increased by pulse shaping laser systems. reducing the occurrence of defects such as closure. Laser beam superposition helps to achieve greater productivity and ensures higher process reliability owing to smaller fluctuations in the required Method through-drill time. Holes with a mini- Above: Percussion drilling in a multi-layer system with mum diameter of 150 µm can be closure by melt. By spatially and temporally superim- drilled through material thicknesses Below: Longitudinal section posing two laser beams, the drilling of up to 10 mm (bottom image left). of drill holes made with super- speed in stainless steel and aluminum imposed DPSS laser radiation in stainless steel 5 mm thick. can be increased by up to a factor of Drill-hole diameter: approx. 4. In this case, the output of a diode- 130 µm. pumped Nd:YAG solid-state laser is Contact superimposed on that of a lamp-pumped Nd:YAG slab laser. Holes were per- Dipl.-Phys. M. Brajdic, Tel.: -205 cussion-drilled in different material [email protected] thicknesses (5.8 and 10 mm) and the Dipl.-Ing. K. Walther, Tel.: -409 through-drill time was measured in [email protected] each case. Dr. I. Kelbassa, Tel.: -356 [email protected]

92 Fraunhofer ILT Annual Report 2006 Drilling and cutting of contoured holes

the geometries that can be generated Task and the reproducibility of the results obtained. Depending on the specifi- Hot gases subject turbine components cations, a variety of hole geometries to extreme thermodynamic stress dur- (e.g. conically tapering or elliptical) ing operation. In order to ensure reli- can be realized in a range of materials able long-term turbine operation and and material combinations (metals, high levels of efficiency at high tempe- ceramics, multi-layer systems and com- ratures, nickel-based superalloy coat- posites). ings are employed in the manufacture of turbine components. In addition, the turbines must also be effectively cooled. In a process known as effusion Results and Applications cooling, an increase in the density of the cooling holes (up to 100 holes per • The realization of contoured holes cm2) ensures a uniform distribution of by means of 5-axis trepanning is not the coolant fluid over the surface of confined to contouring the exit area the component concerned. A direct of the hole, but can be achieved interaction with the stream of hot gas along the entire length of the hole Above: Laser-drilled contoured that would lead to loss of efficiency through the workpiece. holes in high-pressure-turbine is thus avoided. The holes are aerody- • Holes typically have a diameter blades, Source: MTU Aero namically contoured to increase the of ≥ 0.2 mm and a depth of up to Engines. efficiency of cooling by ensuring the 5 mm. presence of a uniformly distributed • The thickness of the recast on the coolant film close to the surface of the walls of the hole is ≤ 20 µm. component. • A closed process chain (including a CAD/CAM/CNC interface) that is capable of realizing variable hole geometries in OEM components is Method available for the drilling and cutting of contoured holes. The parameters of the freeform contoured surfaces of the holes are calculated with the help of flow simu- lations. These data are then transferred Contact to the positioning system via a closed CAD/CAM/CNC chain. After the pro- Dipl.-Ing. K. Walther, Tel.: -409 cess control parameters and process [email protected] parameters have been established in Dr. I. Kelbassa, Tel.: -356 a test run, the contoured holes are [email protected] produced in a two-step process: 1. A through-hole is pierced by percussion drilling, centered on Above: Section through a hole the longitudinal axis of the desired in a multi-layer system (heat in- contoured hole. sulation layer yttrium stabilized zirconium, corrosion resistant 2. The cooling hole is then cut to layer MCrAlY, nickel superalloy its final shape by means of 5-axis CMSX-4), showing the flow trepanning. vectors of the hot gas (red) and the coolant (blue). Below: Exit surface of con- The viability of the process has already toured holes in a multi-layer 2 mm been demonstrated on arrays of drill system. holes and it is being continually im- proved in terms of process cycle times,

Fraunhofer ILT Annual Report 2006 93 Offline determination of workpiece-penetration during percussion drilling

Task Results and Applications

When using a Nd:YAG laser for per- There is a distinct decrease in the ave- cussion drilling, it is not possible to rage intensity of the process emissions determine the exact number of pulses during the pulse that completely pene- required to completely drill through trates the workpiece. After drill- workpieces having a thickness ranging through, the average intensity never from a few millimeters to several centi- exceeds the threshold level (see middle meters. This is due to instabilities in picture, 8th and 9th pulse). The aim the process such as pulse-to-pulse of future research is to allow online fluctuations. The number of pulses is determination of the drill-through therefore normally set at a (higher) level point during percussion drilling. that is certain to achieve complete penetration of the workpiece, which The signal-to-noise relationship before usually means that the piece is irradiated and after drill-through is most clearly 1 mm with a number of ‘extra pulses’ after discernable in the red band (wave- it has been drilled through. The use of lengths 600 - 850 nm). In the center a coaxial high-speed camera to deter- of the process emission intensity dis- 7. pulse mine the exact drill-through point is tribution, a minimum is reached after the first step towards controlling the penetration of the workpiece (bottom y t i s 8. drill-through number of pulses more accurately, in image left). Further investigations are n e

t order to reduce process cycle times to be carried out with the aim of finding n i

e threshold level and avoid unnecessary damage to the a method to establish the diameter of g a r 9. pulse rear wall of the workpiece when drilling the drill hole on the basis of the inten- e v

a hollow objects. sity distribution pattern.

There are potential applications for image number this technique in all areas where high- Method volume laser percussion drilling is employed, for example in the drilling Experiments were carried out to deter- of cooling holes in gas turbine compo- mine the drill-through point for 2-8 mm nents, or the manufacture of filters. thick workpieces made of standard Fe and Ni alloys. Holes were drilled at an inclination of 0° and 45°. A Nd:YAG laser system with pulse durations of Contact 0.5 -2 ms, pulse energies < 12J and processing optics with a focal length Dipl.-Ing. K. Walther, Tel.: -409 150 mm was employed. A CMOS ca- [email protected] mera system with a repetition rate of Dr. I. Kelbassa, Tel.: -356 Above: Longitudinal section 50 kHz at a resolution of 96 x 96 pixels [email protected] through a percussion drill hole, 8th pulse, material: René 80. and a color resolution of 3 x 8 bits was Middle: Average intensity of employed for the coaxial high-speed the sensor signal. photography. Below: False color representation of the intensity distribution of the sensor signal. The process emissions of molten metal, vapor and plasma were recorded dur- ing drilling and later analyzed. Color separations were made of the resulting images and each elementary color ana- lyzed individually.

94 Fraunhofer ILT Annual Report 2006 Efficient expulsion of melt during laser percussion drilling

Task Results and Applications

Percussion drilling by means of a laser The realization of the drill-hole by the beam is an economically attractive pro- expulsion of metal in a molten state is cess that is especially suitable for high- characterized by the acceleration of volume processing. However, its wider melt that develops at the base of the industrial implementation is hindered hole and its subsequent deceleration by the tendency of molten metal to along the wall of the drill-hole. The re-solidify on the wall of the drill-hole. formation of recast is the result of a The formation of this ‘recast’ seriously steady state that develops in the hole. impairs the quality of the drill-hole and This steady state is dependant on three the efficiency of the drilling process, as main factors: the heating of the surface the layer of recast that accumulates on of the molten metal, heat transmission the drill-hole wall increasingly shields within the flowing melt and heat dissi- the bottom of the hole from the laser pation in the surrounding material. The beam. The ILT was therefore requested thickness of the film of melt along the by an end user of the technology to wall of the drill-hole, the proportion of investigate methods for avoiding the re-solidified melt and the displacement buildup of recast on the drill-hole wall. of melt at the entrance to the drill-hole are calculated in relation to the global parameters of the laser radiation at the base of the hole. Analysis of the model Method indicated that almost all of the molten metal can be expelled when not only A model of the percussion drilling the base, but also the walls of the Left: : Recast (grey) and the process was employed to analyze the drill-hole are heated. This is achieved molten metal (blue) shielding effect of a number of process variables by adjusting the spatial and temporal the bottom of the drill-hole on the cooling of the molten metal parameters of the pulse. from the laser beam. Right: Almost complete expul- as it flows out of the drill-hole. Several sion of the molten metal by options for heating the wall of the heating the drill-hole wall. drill-hole were investigated and their influence on the formation of recast Contact was analyzed. Dipl. Phys. U. Eppelt, Tel.: -163 [email protected] Prof. W. Schulz, Tel.: -204 [email protected]

Fraunhofer ILT Annual Report 2006 95 Effective ray tracing for multiple reflections during laser cutting and drilling

Ray tracing in three spatial dimensions Task is considerably more complex than in two dimensions, and involves discretiz- A necessary task when simulating laser ing the surface of the component and manufacturing processes is the calcu- every beamlet into triangular sections. lation of the propagation, reflection The number of computations required and absorption of the laser radiation to divide the energy transported by the on the surface of kerf or drill-holes. beamlet among adjacent triangles is The aim of this project is to investigate considerably greater. The local propa- the effect on product quality of the gation direction of the rays is of consi- multiple reflections produced as the derable importance for the calculation beam is repeatedly reflected and reab- of absorption and reflection (Poynting sorbed by the workpiece. The customer vector). additionally required a detailed analysis of the effects of the direction of pro- pagation and the polarization of the beam. The necessary geometrical-optical Results and Applications calculations were carried out with the help of a ray tracing technique. An The 2-D or 3-D ray tracing program analysis of the results will enable allow- developed by the ILT can be used to ances to be made for wave-optical investigate the relationship between phenomena. reflections and the formation of qua- lity-relevant features, such as ripples and adherent dross, in any laser manu- facturing process. During laser cutting Method processes, multiple reflections play an important role in the formation of A ray tracing algorithm for two-dimen- ripples and adherent dross. sional and three-dimensional surfaces was produced. The distribution and Above: Ray tracing of a divergent propagation direction of the beam and beam of power P0. Division into 5 beamlets (power P1 - P5) and direc- the surface of the component were Contact tions on the surface. approximated with piecewise linear Below: 3-D ray tracing of a cutting functions. The partial rays (beamlets) Dipl. Phys. U. Eppelt, Tel.: -163 process. were generated by geometrical-optical [email protected] slicing and mapped onto the surface Prof. W. Schulz, Tel.: -204 of the workpiece using the ray tracing [email protected] algorithm. The beamlets are characte- rized by the energy they transport and peripheral beams. When a beamlet strikes the surface, its energy is divided between the surface and those portions of the beam that are absorbed or re- flected.

96 Fraunhofer ILT Annual Report 2006 High-speed microdrilling of transparent metal foils

Task Results and Applications

There is an increasing need for micro- This drilling method has been shown to drilling techniques to produce micro- be capable of drilling holes in a variety scale holes in medical devices and en- of materials at a rate of between 150 gineering products, e.g. for ventilation and 300 holes per second. The maxi- or drug dosing. The diameter of these mum size of the scan field defining the holes commonly lies in the region of machining zone for simultaneous drill- < 20 µm, drilled in materials with a ty- ing of holes is 10 x 10 mm. If holes pical thickness of 50-100 µm. Several need to be drilled over a larger area, a thousand such holes may be required, linear-motion positioning table can be at a drilling rate of > 100 holes per se- used. cond. The layout, number and diameter of the holes varies according to the cus- The lowest achievable diameter of the tomer’s requirements, hence the need drill holes lies between 10 and 20 µm. for an easily adaptable system. The minimum spacing between the center of two holes, without melting the metal bridge between them, de- pends on the type of material. The nar- Method rowest achievable bridge width ranges between 8 µm (for titanium or tungsten) To achieve the necessary small hole dia- and 30 µm (for steel). meters, the method employs a frequen- cy-tripled Nd:YAG laser focused using a At very small hole diameters of 10 µm, lens with a short focal length. A galva- it is possible to achieve a transparency nometric scanner is used as a flexible, of the metal foil of over 20%. rapid means of positioning the laser 200 µm beam. The workpiece is positioned with the aid of a 3-axis system. Contact The arrangement of drill holes in the scan field is transmitted to the software Dipl.-Ing. (FH) C. Hartmann, Tel.: -207 via a CAD/CAM link. Defining the hole [email protected] pattern via a CAD/CAM link makes this Dr. A. Gillner, Tel.: -148 a very flexible solution, with which it is [email protected] possible to produce different patterns of drill holes very quickly. Similarly, the software allows the drilling parameters 200 µm to be adapted to the material and to the required precision. Above: Diagonal view of a micro-perforated metal foil. The perforated field measures 7 mm x 7 mm. Middle: Perforated titanium foil with drill holes in a triangular arrangement. Foil thickness 50 µm, hole diameter 20 µm. Below: Perforated titanium foil with drill holes in a square arrangement. Foil thickness 50 µm, hole diameter 20 µm.

Fraunhofer ILT Annual Report 2006 97 Microdrilling of holes in pharmaceutical packaging for the validation of test equipment

Task Method

Leak testing forms an essential part An ArF excimer laser is typically used of the quality assurance process for to produce test holes in disposable packaged forms of pharmaceutical packaging specimens (image bottom products. To validate and calibrate the left). In the first instance, test holes are leak testing equipment, the product drilled as a means of calibrating the laser manufacturers need to prepare refe- system. The size and shape of these rence specimens containing fine holes holes is examined using a light micros- with a diameter typically in the order cope and a scanning electron micros- of 5-100 µm. The drill holes must be cope. Then the reference specimens smooth and burr-free, to prevent them are prepared. The fact that the holes from becoming clogged when inserted are produced by means of laser ablation, in the test equipment. Depending on a non-contact process, means that the the product characteristics and the specimens can even be handled in a failure mode, precision drill holes are sterile environment. required in different places and through different wall thicknesses. Above: Test hole drilled in PE. Below: Specimens of products for testing. Results and Applications

Reference specimens for use in the va- lidation and calibration of leak testing equipment are produced to the dimen- sions specified by the customer. Holes of consistently high quality can be drilled in packing materials such as PE, PP, PEEK or COC to extremely small diameters, down to a few micrometers (top image left). The tolerance of these holes generally lies in the region of ± 1 µm. The edge of the holes is slight- ly rounded, and it can be assured that there are no open pores, burrs or loose particles.

Contact

Dipl.-Chem. P. Jacobs, Tel.: -135 [email protected] Dr. M. Wehner, Tel.: -202 [email protected] Dr. A. Gillner, Tel.: -148 [email protected]

98 Fraunhofer ILT Annual Report 2006 Laser-diode-assisted transformation of plant cells

Task Results and Applications

The agronomic properties of plant cells Exposure to laser light makes the cell can be significantly improved by means membrane temporarily permeable. of targeted gene transfer (transforma- During this period, it is possible for tion). Transgenic plants grown from exogenous matter to migrate from the such cells demonstrate, for example, surrounding medium into the cell. The a greater resistance to plant pathogens transient transformation of individual or herbicides, an increased vitamin A protoplasts was demonstrated with and C content, or later cropping ma- the aid of a reporter gene (EYFP) (see turity. However, conventional methods image). Excessive doses of laser light present certain disadvantages, depend- cause damage to the cell membrane, ing on the plant cell, and their trans- which results in the death of the cells. formation efficiency typically lies below The exposure must therefore remain 1%. The aim of the project is to raise within a narrow process window in the transformation efficiency to 10% terms of laser output power and dura- by exposing the cells to light from a tion. laser diode at a wavelength of 405 nm. Successful transformation of a The chief advantages of using a laser BY2 protoplast with expression diode rather than an ultrashort-pulse of the yellow-fluorescing repor- laser are the compact setup, the low ter gene. Method investment costs, and significantly reduced time and effort to install and A laser diode operating at violet wave- operate the laser. lengths, adapted to an inverse micros- cope featuring transmitted light illumi- The described transformation process nation and fluorescence diagnosis, is enables specifically selected single cells used to perform optoporation on the in a large colony to be transformed cells. The cells are exposed to laser and unwanted cells to be eliminated light at a tangent to their edge for a directly. By implementing image analy- predetermined length of time. Pene- sis software to determine the position, tration of a fluorescent dye from the shape and orientation of individual surrounding medium indicates that per- cells, it is possible to automate the meabilization (optoporation) has taken process to a certain degree, with auto- place. The fluorescent marking allows mated positioning of the laser with cells in which optoporation has failed respect to single cells, and automated to be filtered out, leaving behind a cell light exposure. population of which it can be expected that the cells will express the target gene with a high degree of efficiency. Contact This project is being carried out in col- laboration with the Fraunhofer Institute Dipl.-Chem. P. Jacobs, Tel.: -135 for Molecular Biology and Applied [email protected] Ecology (IME). Dr. M. Wehner, Tel.: -202 [email protected] Dr. A. Gillner, Tel.: -148 [email protected]

Fraunhofer ILT Annual Report 2006 99 Temporally resolved quantitative phase microscopy

using three CCD cameras. Analysis Task with IATIA® Qpm® software simulates different methods and types of mea- The standard technique of interfero- surement used in phase-contrast micro- metry has limited usefulness in dy- scopy, such as differential interference namic process monitoring because it contrast, Hoffmann modulation con- generally only allows quantitative in- trast, or Zernike phase contrast (bottom formation to be obtained for phase image left). To obtain a time resolution changes in the order of magnitude of of ≥ 100 fs and detection times of π. A novel computer-assisted technique up to 1.6 µs, an ultrashort-pulsed involving quantitative phase micro- laser beam (fs laser beam) and multire- scopy can be used to visualize tran- flecting delay lines are used. The sys- sient processes on time scales varying tem’s functionality includes computer- between 100 fs and 1.5 µs, typical of assisted synchronization and control of industrial processes such as laser ma- light-source parameters such as inten- terials processing. By interpreting the sity, delay, exposure time, synchronized quantitative phase measurements it operation of the CCD cameras and is possible to derive information on analysis of the recorded images using three-dimensional changes in the geo- QPm® software (top image left). metry of microstructures or variations in the refractive index. The technique is not dependent on the spatial or tem- poral coherence characteristics of the Results and Applications beam source. The non-destructive technique can be employed to visualize processes in laser materials processing, such as welding, Method drilling or ablation. It is equally suitable for applications in the life sciences, Numerical solution of the transport especially the observation of living cells of intensity equation offers a route without having to add toxic dyes as to quantitative phase microscopy. contrast agents. The algorithm based on this equation enables the phase information to be reconstructed from three normal bright-field images of an object or a Contact process captured on three imaging planes (1 focused and 2 defocused Dipl.-Phys. I. Mingareev, Tel.: -535 with a shift of e.g. ∆z = ± 0,5 - 10 µm). ilja.mingareev@ ilt.fraunhofer.de 10 µm To achieve this, the images are captured Dr. A. Horn, Tel.: -205 simultaneously on the three planes alexander.horn@ ilt.fraunhofer.de Dr. I. Kelbassa, Tel.: -356 [email protected]

Oben: Schematic layout of the phase-contrast microscope. Middle and below: Laser-in- duced modification of a copper surface. Middle: Image taken using a reflected-light micros- cope. Below: Zernike phase 10 µm contrast image computed using QPm® software.

100 Fraunhofer ILT Annual Report 2006 Laser Plant and System Technology Business Area Laser Plant and System Technology

This business area focuses on the deve- lopment of prototype equipment for laser and plasma-technology applica- tions, as well as on laser systems en- gineering, particularly in the fields of automation and quality assurance. Areas of application embrace welding, cutting, hardening, repair coating, drilling and micro-joining. The system technology offered provides complete solutions for process monitoring, com- ponents and control systems for preci- sion machining, laser-specific CAD/CAM technology modules, as well as soft- ware for measurement, open- and closed-loop control and testing. For its work in process monitoring in parti- cular the business area can draw on extensive and, where required, patent- protected know-how. In this sector nu- merous systems have already been li- censed for companies. Target markets Development of cladding heads include laser equipment and compo- for laser cladding. nent manufacture as well as all sectors of production industry which deploy lasers in their manufacturing activity or intend to do so.

102 Fraunhofer ILT Annual Report 2006 Contents

Laser cutting plant for paperboard/polymer laminates (blister packs) 104

Repair of gearbox components by means of laser cladding 105

Autonomous seam tracking for laser welding applications 106

CPC-based process monitoring for high-volume industrial laser welding of camshafts 107

Continuous process monitoring during laser welding of thin aluminum sheet 108

Process monitoring during transmission laser welding of plastics 109

European Laser Institute ELI 110

Note from Institute Director We would like to point out that the publication of the following industry projects has been coordinated with our customers. In principle, industry projects are subject to the strictest obligation to maintain secrecy. We would like to take this time to thank our industrial partners for their willingness to have their reports listed published.

Fraunhofer ILT Annual Report 2006 103 Laser cutting plant for paperboard/polymer laminates (blister packs)

Task Results and Applications

The aim of this project is to improve On the basis of these experiments, a the performance of a packing machine concept for a laser cutting system was used to pack small engineering parts developed that would allow the cus- on blister cards made of a paperboard/ tomer to calculate the cost of replacing polymer laminate (see top picture). the mechanical cutters by a laser system. Currently, parallel rotating cutters are This primarily involved selecting an employed to separate individual packs appropriate laser source, traveling axes from the strips of 16 carded blisters and a control system, and designing as they travel widthwise through the the beam source, deflection mirror and machine. In future, lasers are to be cutting-head unit arrangement. used for this purpose, in order to im- prove the cut quality. In a 4-head cutting unit, a cutting speed of 320 mm/s can be achieved, requiring an output of 110 W per Method beam. A system with a maximum out- put power of 500 W was selected as Given the high absorption of infrared a beam source. The cut edges are wavelengths by paperboard and plas- smooth and burr-free (see bottom

tic, a CO2 laser (wavelength 10.6 µm) picture). The low levels of smoke resi- with high beam quality (K = 0.92) was due, typical when cutting paperboard, selected for this application. It can be are within acceptable limits and can be focused to a beam diameter of appro- concealed with the help of appropriate ximately 100 µm using a lens with a printing. focal length of 63 mm. This system is capable of generating beam intensities of 106 W/cm2 that are typically neces- sary to cut such materials. The required Contact Above: Blister pack consisting of a preformed polymer film (0.35 mm cutting speed was determined as a thick) laminated onto printed card function of the specified cycle time Dipl.-Phys. G. Otto, Tel.: -165 (0.35 mm thick). of three seconds, the cut-length for [email protected] Below: Cut edge of a paperboard/ an individual blister pack, and the time Dr. A. Gillner, Tel.: -148 polymer laminate (0.70 mm thick). The laser beam is directed onto the material taken to position the workpiece. By [email protected] from above (the polymer side). employing multiple cutting heads mounted in parallel, the cutting speed can be reduced to such an extent that it is not necessary to mount the heads on expensive traveling axes. Using the cutting speed thus obtained as a benchmark, initial experiments were carried out to establish the necessary laser output power and the cutting gas pressure and focal position required to produce a burr-free edge.

104 Fraunhofer ILT Annual Report 2006 Repair of gearbox components by means of laser cladding

The main components of the system Task are: • a modified lathe with an additional A wide range of coating techniques linear axis for setting the track dis- are employed for the repair of mecha- placement. nical components, for example electro- • a 2 kW fiber-coupled diode plating, thermal spraying or conven- laser and the necessary optical tional cladding techniques (plasma components. powder, tungsten inert gas welding). • a Fraunhofer ILT cladding head with Laser cladding offers a number of ad- an integrated three-jet powder vantages in comparison to these pro- nozzle which allows operation in cedures; these include improved metal- confined conditions. lurgical bonding of the coating and the substrate, low heat transfer to the workpiece, and the possibility of depo- siting layers of varying thickness from Results and Applications 1/10 mm to several mm by utilizing multi-layering techniques. A variety of gearbox components were repaired and, in the process, customer- Above: 3-D drawing of the opti- The aim of this project was to qualify specific coatings with a hardness of cal system; including collimation laser cladding as a technique for the 36 to 60 HRC and a depth of between optics, focus optics, CCD camera repair of gearbox components and to 0.3 mm and 0.7 mm were realized. and flange-mounted powder nozzle. implement and integrate the system Below: Repair of gearbox on-site at the customer’s premises, The technology was installed and components by means of laser where it would replace existing elec- integrated at the customer’s site in cladding. troplating technology (hard chrome Rotterdam, where it has been used for plating). repairing gearbox components since mid-2006.

The laser cladding process and techno- Method logy developed by the ILT is also sui- table for repairing other mechanical During the first phase of the project, parts, turbine components, molds or a variety of gearbox components were tools for example. repaired at the Fraunhofer ILT by laser cladding. The results of these repairs The project was carried out in collabo- were then validated by the customer. ration with the company Stork Gears & On the basis of the data thus gained, Services in Rotterdam. the specifications for the system were drawn up. A customer-designed lathe is used for manipulating the parts. Only rotationally symmetrical components Contact are to be worked. Dr. A. Gasser, Tel.: -209 [email protected] Dr. K. Wissenbach, Tel.: -147 [email protected]

Fraunhofer ILT Annual Report 2006 105 Autonomous seam tracking for laser welding applications

and determines the relative speed Task between the sensor and the workpiece in two axes. In addition, it detects Commercial seam tracking systems the position of the seam by grayscale measure the position of the joint to image analysis. On the basis of this in- be welded in advance of the welding formation, the trajectories of the robot zone. Deviation in the position of the arm and the weld seam, and therefore joint is then compensated for by ap- the necessary correction vector, can be propriate on-line corrections to the calculated for every point in time. The trajectory of the welding path or by coaxial arrangement of the sensor to an additional axis (linear axis or tilting the beam path allows 360°monitoring axis). However, the delay resulting of the seam position around the inter- from the forerun of the sensor must be action point. Seam tracking is there- taken into account when calculating fore possible in two axes, obviating path corrections. Such systems are very the need for a rotational axis. In this sensitive to feed rate variations. This is system, corrections to the beam posi- due to the fact that the seam tracking tion are carried out by a scanner mirror algorithm does not receive any infor- mounted in the beam path (see top mation about the robot hand move- photo). ment after the seam position has been determined. Error-free seam tracking is therefore dependent on the following requirements: Results and Applications • The path accuracy of the robot must be within the required positioning As the relative motion of the workpiece accuracy. and the position of the joint are deter- • The workpiece must not be mined simultaneously, a butt joint can displaced or deformed during be tracked autonomously. This allows processing. precision laser welding to be carried • The processing head must not be out either manually or by relatively Above: Laser welding system with autonomous seam tracking. rotated. basic, inexpensive robots incapable of Below: User interface, auto- achieving high path accuracy or with nomous seam tracking of a si- Additionally, every welding application only limited interfaces. The rough posi- nusoidal joint. Real-time sensor has to be calibrated at a so called tioning of the processing head is car- image of the workpiece (left); measured course of the seam ‘golden workpiece’ in order to com- ried out by the handling system (robot on the workpiece (right); mea- pensate lateral movements of the robot. or manual) and the fine positioning is surement signal of the relative The feedback to the robot control re- carried out by actuators integrated in displacement of workpiece and processing head, seam position quires laborious integration. The aim the processing head. Processing errors, and correction vector (below). of the autonomous seam tracking is to that can occur when using conven- develop a processing head that relies tional seam tracking systems, resulting exclusively on on-board sensor and from inadequate path accuracy of the actuation systems to correct deviation robot, deformation of the workpiece between the robot trajectory and the during processing or processing head seam trajectory and therefore is inde- rotation, are therefore eliminated. pendently of the robot control system and prior calibration.

Contact

Method Dipl.-Ing. B. Regaard, Tel.: -320 [email protected] At the Fraunhofer ILT, an optical Dr. S. Kaierle, Tel.: -212 measuring system was developed that [email protected] monitors the surface of the workpiece 106 Fraunhofer ILT Annual Report 2006 CPC-based process monitoring for high-volume industrial laser welding of camshafts

A number of evaluation strategies were Task tested during the project. The most im- portant criteria for selecting an evalua- The company LBBZ GmbH carries out tion technique were the reliability with high-volume laser welding of camshafts which defective parts were identified for the automobile industry. The con- and its ability to be used online. The struction of a camshaft can be seen in objective was to achieve a 100% de- the top photo. The weld seam on the tection rate for defective welds and a camshaft rod (see close-up) joins the pseudo-defect rate that was as low as rod with the cams. The component is possible. butt-welded with a CO2 laser system. Quality control is primarily carried out by the machine operator who visually inspects each welded part for defects. Results and Applications Badly made camshafts or units with weld defects which fail during later The required detection rates could be operation can have significant follow- achieved using an evaluation system up cost implications for the manu- that compares the recorded process facturer. The identification of defective images with reference images. The welds is therefore of considerable im- bottom photo shows the evaluation re- portance. The aim of the project was sults for a good weld and a poor weld. to ensure continuous on-line monitor- The amplitude peak visible in the eva- ing of the camshaft welding process luation signal is typical for a defective with the help of the CPC process con- weld. As this image shows, the system trol system. can determine the exact point in time when the defect occurs. From this it is possible to directly derive the exact lo- cation of the defect in the weld seam. Method The evaluation parameters could be Above: Camshaft with laser set at a level that resulted in a very low weld seam. Below: Evaluation results for The process emissions produced by incidence of pseudo-defects and a a good and a poor weld. the laser welding process are reflected 100% detection rate for faulty welds back into the path of the working beam. in a production run of several hundred A proportion of this reflected light components. is coupled out of the beam path by means of a small mirror mounted to A 100% success rate was therefore the side of the beam, and mapped on- achieved with this system. This process to the high-speed camera incorporated is, of course, also transferable to other in the CPC system via an optical system. laser welding applications. This optical system was designed to ensure the best possible image quality. The process images are simultaneously recorded and evaluated by the CPC Contact system and its analysis software. Dipl.-Ing. J. Kittel, Tel.: -136 [email protected] Dipl.-Ing. P. Abels, Tel.: -428 [email protected] Dr. S. Kaierle, Tel.: -212 [email protected]

Fraunhofer ILT Annual Report 2006 107 Continuous process monitoring during laser welding of thin aluminum sheet

Task Results and Applications

The purpose of this project was to The selected types of imperfection are investigate a technique for process detectable using the camera-based monitoring during laser welding of monitoring unit. The system is capable aluminum-polymer composite piping. of visualizing spatter and melt-pool The main aim was to determine the overflow (see middle and bottom scope of a camera-based sensor system photos) at welding speeds of up to for the detection of welding imper- 50 m/min. At higher speeds, motion fections and to assess its suitability for blur limits the resolution of the image

deep-penetration weld use in a continuous quality monitoring and thus the size of defects that can s s e n system. be identified. In such cases, holes can k c i h t be detected if the light emitted by the t e e h

s secondary light source is reflected by a full-penetration weld surface behind the workpiece. Defects Method can be identified on the basis of varia-

welding speed tions in the surface texture. Pores can On the basis of an analysis of the dy- only be detected at diameters equal Above: Full-penetration weld namic processes in the welding zone, to or greater than the thickness of the at PL = 1 kW, rF = 184 µm, 1050 A (Al 99,5). a selection was made of the imper- metal sheet. Middle: Spattering at fections covered by EN13919-2 which vs = 28 m/min, s = 0.4 mm. seemed most suitable for detection Lack of fusion in butt joints can be Below: Image perpendicular using imaging techniques; these inclu- detected if the seam surface is not to the seam surface. ded welding spatter, melt-pool over- concave, because the incident light flow, holes and lack of fusion. from the secondary source is reflected back into space by the curved surface. The coaxial process control (CPC) sys- Processes leading to defects resulting tem with a secondary light source was from the re-solidification are only de- chosen as the imaging system. In the tectable to a limited extent. Those de- first instance, the performance limits of fects that cannot be readily identified the imaging process were established, with the current arrangement require given that high welding speeds are alternative illumination concepts. necessary to ensure the productivity and economic viability of the welding Image quality can be improved by in- process. creasing the frame rate and shortening the exposure time, thus allowing pro- Illumination levels and sensor parame- cess monitoring to be carried out at ters were optimized for the monitoring higher welding speeds. of welding imperfections. The parame- ters of the welding process itself were deliberately set at levels that would provoke defective welds. Contact

Dipl.-Ing. M. Dahmen, Tel.: -307 [email protected] Dr. S. Kaierle, Tel.: -212 [email protected]

50 µm

108 Fraunhofer ILT Annual Report 2006 Process monitoring during transmission laser welding of plastics

Task Results and Applications

Transmission laser welding of plastics A processing head with an integrated has become an established technique sensor system for plastics welding in industrial manufacturing. However, applications was designed and con- a number of disruptive factors relating structed on the basis of a modular op- to the component itself, the material tical system developed by the Fraunho- from which it is made, or the produc- fer ILT. The processing head is designed tion environment, can cause deviations to allow the simultaneous monitoring from the ‘optimum processing point’, of heat radiation emitted during the resulting in defective welds. These welding process and the welding pro- factors cannot normally be monitored cess itself with the help of a secondary during the welding process. The aim of light source. This permits the various this project is to investigate a number monitoring strategies to be evaluated of optical monitoring techniques for and the sensor signals to be correlated. laser plastics welding applications and Welding tests are being carried out on to develop a monitoring system for in- polycarbonate, polypropylene and po- dustrial use. lyamide. In later stages of the project, strategies for process monitoring and a prototype processing head for indus- trial use will be made available. These Method are intended to meet the need for im- proved quality control and quality en- The project is being carried out in col- hancement systems in the field of laser 2 mm laboration with the industry partners plastics welding. Amtron GmbH, Huf Tools GmbH Vel- Plastics welding process bert und LIMO Lissotschenko Mikroop- illuminated by a secondary tik GmbH and is funded by the ‘Stif- light source. tung Industrie Forschung’, a private Contact foundation that finances scientific re- search projects. The aim of the project Dipl.-Ing. S. Mann, Tel.: -321 is to compare the specific reliability [email protected] of several monitoring techniques, in- Dr. S. Kaierle, Tel.: -212 cluding spatially integrated or spatially [email protected] resolved coaxial process monitoring, both through measurement of secon- dary emissions and through observa- tions using a secondary light source.

Fraunhofer ILT Annual Report 2006 109 European Laser Institute ELI

Furthermore, the international co- Short Profile operation of industry and research, especially in the field of EU research The European Laser Institute was foun- support, is forced by ELI. Amongst ded in 2003 through an EU-funded ini- others, ELI creates adequate platforms tiative. The ELI mission is to strengthen by organizing conferences, workshops, and further enhance Europe’s position summerschools etc. In the future, this in the field of laser technology. In addi- is supported by the cooperation with tion, ELI aims to raise public awareness the respective representations (e. g. of the significance and prospects of the EPIC, AILU, WLT). A strong cooperation European laser technology industry. ELI with the Laser Institute of America is a network composed of more than (LIA) already exists in the organization 20 leading research facilities including of international conferences (ICALEO, the Fraunhofer ILT as well as small and PICALO, ALAW) as well as the Journal medium-sized companies. This means of Laser Applications (JLA). that in addition to its participation in regional and national competence net- works, as an ELI member the Fraunhofer ILT is also part of an influential, Euro- Executive Commitee pean-level laser technology network. The members of the committee representing the ELI are: • Dr. Stefan Kaierle (chairman), Fraunhofer ILT, Germany • Abdelkrim Chehaibou, Institut de Soudure, France • Dr. François De Schutter, Lasercentrum Vlaanderen, Belgium • Dr. Paul Hilton, TWI, Great Britain • Dr. Wolfgang Knapp, CLFA, France • Prof. Dr. Veli Kujanpää, Lappeenranta University of Technology, Finland • Prof. Dr. José Luis Ocaña, Centro Láser U.P.M., Spain

Contact

Dr. Stefan Kaierle Phone: +49 (0) 241 8906-212 Fax: +49 (0) 241 8906-121 [email protected]

110 Fraunhofer ILT Annual Report 2006 Laser Measurement and Testing Technology Business Area Laser Measurement and Testing Technology

The services provided by this business area include the development of mea- surement and testing processes and related equipment for material analysis and for geometric testing and surface inspection. The requisite measurement and testing software is tailored to customer-specific problem areas. Material analysis is based on the deployment of laser-spectroscopic processes, focusing on the analysis of metallic and oxidic materials, identification testing of high- alloy steels, rapid recognition of mate- rials for recycling tasks and analysis of gases and dust. Special electronic com- ponents are developed for the parallel processing of detector signals of high bandwidth.

In biophotonics joint projects are car- ried out in the field of highly sensitive fluorecence detection for protein chips SILAS - Rapid identification and laser scattered light measurements of light metal alloys for automated sorting. in sub-µl test volumes for protein crystallization. As part of the area’s work on geometric testing and surface inspection components, devices and equipment are being developed for obtaining 1 to 3D information about the geometry or surface properties of workpieces. These include processes and special systems for testing the stability of bar and strip products and devices for the 1D to 3D scanning of unit goods. Target markets include the production and the recycling industry which conduct measurement and testing fast and close to the process.

112 Fraunhofer ILT Annual Report 2006 Contents

Blue lasers for ultra-high precision Remote analysis using triangulation - BLU 114 laser-induced breakdown spectroscopy - TeleLis 124 Scanning system for laser-induced breakdown Optical stand-off detection spectroscopy - ScanLis 115 of explosives and improvised explosive devices (OFDEX) 125 Rapid laser-based elemental analysis of slag samples 116 Confocal laser-scanning microscopy with multiphoton Rapid identification of light excitation 126 metal alloys for automated sorting - SILAS 117 Optical coherence tomography (OCT) in intra- Rapid laser-assisted analysis operative tissue diagnostics 127 of metallic and non-metallic inclusions in steel - REAL 118 Integrated microfluidic diagnostic systems - IMIKRID 128 Laser analysis of corrosive change in building materials 119 MultiLas - a laser endoscope for the multimodal treatment Rapid preparation and analysis of brain tumors 129 of process samples by laser 120 Endoscopic laser coagulation Improved solid-state laser system for the intraoperative microablation processes with cauterization of blood vessels 130 tailored pulse trains 121 Application system for intracranial Single particle analysis for photodynamic therapy - PDT 131 the separation of minerals during the extraction of primary A rational approach to protein raw materials - EIGER 122 crystallization based on optical measuring techniques 132 Characterization of ultrafine dust particulates in industrial process emissions 123

Note from Institute Director We would like to point out that the publication of the following industry projects has been coordinated with our customers. In principle, industry projects are subject to the strictest obligation to maintain secrecy. We would like to take this time to thank our industrial partners for their willingness to have their reports listed published.

Fraunhofer ILT Annual Report 2006 113 Blue lasers for ultra-high precision triangulation - BLU

geometrically adapted irradiation Task patterns on the object being measured. A time modulator is included for the The growing demand for dimensional purpose of enabling time-division multi- accuracy and surface quality, for exam- plexing and expanding the dynamic ple in the steel processing and auto- range. The sensor is to be constructed motive industries, calls for non-contact on a stable and lightweight optical plat- sensor concepts capable of measuring form. To conclude the project, the newly with an accuracy in the micrometer developed sensors are to be tested for range and below. Systems of this various industrial applications. kind must satisfy the requirements of modern flexible manufacturing lines, The project is being carried out with the which includes automated process financial support of the German ministry and quality control, in terms of speed, of economics, various industrial partners reliability and ease of use. Compact, and the Fraunhofer-Gesellschaft. non-contact distance sensors operating on the basis of laser triangulation are eminently suitable for such purposes. Results and Applications

A test setup was constructed in the Method laboratory for later testing of the sen- sors, and initial measurements were The objective of the project is to develop taken to compare red and blue laser triangulation sensors having a higher diodes for triangulation sensors. Various spatial resolution and accuracy than the setup configurations and detectors products that are commercially available were tested at the same time, the at present. The use of blue laser diodes most important of these being CCD is expected to improve parameters such and CMOS detectors which were tested as spatial resolution, signal-to-noise ratio for their suitability for deployment in and accuracy. An integrated spatial beam the blue-violet wavelength range. modulator is designed to produce

Blue laser beams are used for triangulation. Contact

Dipl.-Ing. (FH) A. Lamott, Tel.: -133, [email protected] Dr. R. Noll, Tel.: -138, [email protected]

114 Fraunhofer ILT Annual Report 2006 Scanning system for laser-induced breakdown spectroscopy - ScanLis

Task Results and Applications

Both in metallurgy and in the metal The system is capable of recording working industry, there is a growing spectra at a pulse repetition rate of need for rapid alloy analysis methods. 20 Hz. The laser employed permits This applies not only to the develop- analyses with single and double pulses. ment of new materials and processes, The spectrometer has 30 channels in but also to process and quality control. the wavelength range from 130 nm Laser-induced breakdown spectroscopy to 589 nm. The integrated software is an interesting alternative to conven- package enables to create and to apply tional spectroscopic techniques in this calibrations for a variety of matrices. context. Its main advantages are that there is no need to prepare the samples and that no physical contact takes place between the sample and the Contact measuring instrument. Dipl.-Ing. (FH) R. Fleige, Tel.: -133 [email protected] Dr. R. Noll, Tel.: -138 Method [email protected]

ScanLis was designed for the analysis of low-alloy steels and of coatings on sheet metals. It was developed as a modular system to cater for these dif- fering applications. The sample stand module serves to analyze process con- trol samples and reference samples of the usual sizes. An extension arm and a Above: ScanLis with sample UV module make it possible to analyze carrier module fitted. strip products, for instance traveling Below: ScanLis with extension along a conveyor belt beneath the ex- arm fitted. tension arm. UV modules with operat- ing distances between 100 mm and 1000 mm are available. In a later, more advanced configuration of the equip- ment, it is planned to include a scann- ing module for raster analysis of sur- faces positioned below the extension arm.

Fraunhofer ILT Annual Report 2006 115 Rapid laser-based elemental analysis of slag samples

Task Results and Applications

During steel manufacturing, a layer The algorithms for processing the mea- of slag is formed on the molten metal. sured values and for operation control Knowing the composition of the slag is were implemented and tested in the an important factor in monitoring the demonstrator, after which the demons- steel manufacturing process. Control trator was set up and put into opera- samples taken from the liquid slag tion at the AG Dillinger Hüttenwerke using a probe (see top figure left) have steel plant. Routine measurements are to be analyzed quickly on site in the performed from the operating panel steel plant. Because the distribution of by the steelworker, who extracts the elements inside the samples is highly sample from the dipping probe and inhomogeneous, this project sets out places it on the sample stand. The to investigate and implement improved measuring process begins as soon as local averaging methods. the cover is closed, and the result is automatically transmitted to the master computer and displayed on the control station. The time taken for the analysis s i s

y measurement of slag samples from production l Method is only 1 minute 20 seconds, conside- a

n measuring time of laser analysis a r

e rably shorter than the approximately s

a regression straight line l

t of the measuring values h Elemental analysis is performed using 4 - 5 minutes hitherto required for the g i e w laser-induced breakdown spectroscopy. analysis of pressed samples, including ideal curve = angle bisector A pulsed solid-state laser generates a the necessary preparation time. luminescent material vapor plasma on the surface of the sample whose radia- The work is being supported financially tion emission is used for spectrochemi- by the European Community Research cal analysis. First, fundamental studies Fund for Coal and Steel (RFCS) and the weight reference value are conducted for spectral line selection Fraunhofer-Gesellschaft. and element distribution, and improved Above: Slag sample taken from the liquid slag layer with a dipping calibration methods are developed for probe. The sample has a diameter a specific sample type. On the basis of of 20 - 40 mm. these results, a demonstrator for on- Contact Below: In a comparison, the laser site use was set up in the steelworks, analysis closely matches the SiO2 reference values obtained in the more thereby minimizing the transport time Dr. V. Sturm, Tel.: -154 time-consuming laboratory analysis for the sample. The results of the laser [email protected] using the borate bead method. analysis were compared with the refe- Dr. R. Noll, Tel.: -138 rence values (see bottom figure left) [email protected] using control samples.

116 Fraunhofer ILT Annual Report 2006 Rapid identification of light metal alloys for automated sorting - SILAS

by laser spectroscopy. The waste mate- Task rial is then automatically separated into two or more fractions on the basis of Aluminum recycling represents an im- selection criteria derived from the entire portant source of secondary raw ma- set of measured values. terials. Apart from conserving natural resources, the recycling of used alumi- num makes it possible to achieve con- siderable energy savings, as it requires Results and Applications only about 5% of the energy input needed for primary production. How- Following the integration and synchro- ever, it is only possible to process alu- nization of all its component modules, minum scrap in secondary melting the SILAS demonstrator will enter a plants to make high-quality aluminum test phase which involves evaluating if the scrap is available in the form of and optimizing the sorting accuracy grade-pure cast or wrought alloys. of the multi-element analysis method. A core aspect of this optimization pro- Unfortunately, there are no automated cess is to eliminate surface contamina- sorting machines able to separate the tion on real scrap samples. This is Snapshot of the online analysis scrap into cast and wrought alloys as achieved by preparing the surface prior of aluminum scrap samples well as into various alloy groups as the to each separate LIBS measurement by using laser-induced breakdown basis for material recycling at a high spatially and temporally adapting the spectroscopy at a conveyer speed of 3 m/s. The exposure level of quality. laser beam output. Subsequently, the time for this image was 1 s. material composition of a representative Under the joint SILAS project a new, partial volume of the object is analyzed laser-based identification method is by laser spectroscopy. being developed which will make it possible to achieve a high material There are plans to upgrade the sorting throughput while simultaneously en- demonstrator to handle other matrices suring that the separated fractions are such as iron, magnesium and minerals. of the highest purity. The aim of the project is to build a demonstrator to validate the functionality of the process under realistic operating conditions. Contact

Dipl.-Phys. Ü. Aydin, Tel.: -431 [email protected] Method Dr. R. Noll, Tel.: -138 [email protected] The method is based on a combination Dr. J. Makowe, Tel.: -327 of image processing, laser-based deter- [email protected] mination of geometric features and la- ser-induced breakdown spectroscopy. In addition to recording the geometric and optical characteristics of the sorted material, the chemical composition of the individual particles is determined

Fraunhofer ILT Annual Report 2006 117 Rapid laser-assisted analysis of metallic and non-metallic inclusions in steel - REAL

Task Results and Applications

The quality of steel is highly dependent Various steel samples were examined on the metallic and non-metallic inclu- for their distribution of metallic and sions it contains. These inclusions, non-metallic inclusions. Different spec- whose size typically ranges from 0.1 µm tral lines were rated for their suitability to 100 µm, must be rapidly detected in analyzing the various inclusions. in order to determine the purity of the This made it possible to create element steel. The analysis is also required to maps with which inclusions such as verify the presence of so-called light MnS can be identified. elements such as C, N, O, P and S, which often cannot be detected by the The work is being supported financially X-ray fluorescence method. As far as by the Research Fund for Coal and possible, the analysis is to be performed Steel (RFCS) and the Fraunhofer-Gesell- without the need for elaborate prepa- schaft. ration of the sample.

Contact Method Dipl.-Ing. (FH) M. Höhne, Tel.: -160 The laser-induced breakdown spectros- [email protected] copy method only requires a ground Dr. R. Noll, Tel.: -138 or milled surface. The focused beam of [email protected] a diode-pumped solid-state laser scans the surface of the sample. A small quantity of the material is vaporized at the focal point of the laser beam to form a plasma. The radiation emitted Above: Section of an element map for the element Mn. by the plasma is spectrally resolved and Below: Section of an element analyzed by a special software program. map for the element S.

118 Fraunhofer ILT Annual Report 2006 Laser analysis of corrosive change in building materials

Task Results and Applications

Various environmental factors, especi- For the detection of chlorine, the ally road salt and vehicle exhaust spectral line at 837.6 nm proved to be fumes, provoke corrosive changes in the most suitable. The upper figure on concrete structures such as bridges the right shows how the averaged line and multistory car parks which can ul- intensity ratio of the analyte line IC1 to timately cause the entire structure to the matrix line ICa varies as a function collapse (see figure bottom right). The of chlorine content. With the present chemicals that cause the most damage state of the art, it is possible to detect are chlorine, sulfur and nitrogen com- chlorine concentrations of 1% and pounds. In a joint R&D project with greater. industrial partners and other public- sector research groups, a process is The project is being conducted with being developed to allow engineers the financial support of the German to determine the depth to which these ministry of economics, various industrial elements have penetrated the struc- partners, and the Fraunhofer-Gesell- concentration weight ture. This is to be followed by the con- schaft. struction of a transportable measuring device for rapid on-site analysis.

Contact

Method Dr. H. Balzer, Tel.: -196 [email protected] Laser-induced breakdown spectroscopy Dr. R. Noll, Tel.: -138 can be used to analyze practically any [email protected] material, even for the presence of hard- to-detect elements such as chlorine or Above: Variation in the spec- sulfur. A pulsed focused Nd:YAG laser tral line ratio ICl837,6/IICa849,9 is used to generate a plasma at the sur- as a function of the chlorine face of a drilled concrete core sample concentration in cement. and the element-specific line emissions Below: Damage to a concrete ceiling as a result of corrosion are measured. The laser parameters caused by chlorine compounds. and the test environment (pressure, shielding gas) are optimized so as to achieve the detection limits for chlorine and sulfur required for the renovation of building structures. The depth profile is obtained by scanning the drilling core.

Fraunhofer ILT Annual Report 2006 119 Rapid preparation and analysis of process samples by laser

Task Results and Applications

In the control of steel manufacturing By directly combining scanning laser processes, it is very important that ablation of the scale layer and subse- the elemental analysis of production quent material analysis by means of samples should be carried out rapidly, laser-induced breakdown emission allowing downstream metallurgical spectroscopy, it was possible to improve Without laser ablation of the scale layer treatment to proceed without delay. the accuracy of the analysis results With prior laser ablation of the scale layer Currently employed methods such as for samples of steel, for instance by spark-discharge optical emission spec- a factor of around 100 for carbon

e trometry, combustion analysis and X- content, by comparison with analysis d i s

d ray fluorescence analysis necessitate without material ablation. e l a c s time-consuming preparation of the samples using mechanical processes The demonstrator built by the project such as milling and grinding. Under team is capable of performing fully the joint ATLAS project a demonstrator automated analyses at several points is being developed as an alternative to on the scale-covered side of metal Concentration the conventional two-step process of samples inserted manually into the

Above: LIBS calibration with mechanical sample preparation followed sample holder. and without prior ablation of by elemental analysis with spark-dis- the scale layer. charge optical emission spectrometry. The Laser Laboratory Göttingen and Below: ATLAS demonstrator. Instead, a single laser-assisted inspec- seven other companies are involved tion system is employed. By eliminating in the collaborative project. The work various intermediate stages, the new is being conducted with the financial method can significantly improve the support of the Federal Ministry of productivity of the steel manufacturing Economics and Labour, the Fraunhofer- process. In the final phase of the pro- Gesellschaft and the participating ject, the demonstrator will be tested in companies. a steel plant.

Contact Method Dipl.-Phys. J. Vrenegor, Tel.: -308 The laser method performs both tasks: [email protected] preparation and analysis. First the scale Dr. R. Noll, Tel.: -138 layer is removed locally by time-modu- [email protected] lated scanning laser ablation and then the bulk material is analyzed using the technique of laser-induced breakdown spectroscopy. The laser method is non- contact and relatively maintenance- free by comparison with conventional milling and grinding.

120 Fraunhofer ILT Annual Report 2006 Improved solid-state laser microablation processes with tailored pulse trains

Task Results and Applications

The aim is to improve the efficiency of The use of picosecond dual pulses im- laser beam microablation during mate- proves the ablation rate by up to 25% rial processing by increasing the abla- by comparison with two single pulses tion rate and quality, while at the same each equivalent to half the burst ener- time reducing the portion of ablated gy, or by 50% by comparison with material in liquid phase. Laser-induced single pulses delivering the same burst breakdown spectroscopy is used to energy. Two ranges can be set for mi- ] r

investigate the induced plasma signal crostructuring with picosecond dual e y a l / for possible correlation with the volume pulses. Range I (interpulse separation m µ [ h t of material removed. By studying the ∆t < 40 ns): low ablation rate, good p e d n o plasma expansion and the propagation processing quality. Range II (∆t ≤ 40 ns): i ablation deptgh single pulse t a l b of compression waves, insights can be high ablation rate but inferior process- a gained into the dynamics of the laser ing quality. The processing quality ablation process. is comparable to that achieved using single pulses of half the burst energy. pulse distance

The plasmas generated during micro- Method ablation are detected using space- resolved measurements, allowing the To date, in most laser-based material plasma dynamics and the internal processes, the laser energy is segmen- structure of the plasma to be studied in ted into uniform, time-equidistant pul- greater detail. Plasmas detected at the Laser beam ses such as Q-switched pulses in the time parameters tdelay = 1 µs, tint = 1 µs axis nanosecond range at a repetition rate feature two distinct areas within the of several times 10 kHz. plasma. In the center, emissions of Fe II spectral lines dominate whereas, on Surface of the sample By using tailored, time-modulated laser the fringes of the plasma, the highest Above: Ablation depth as a pulse trains, the project goal is to im- emission values are recorded for Fe I function of interpulse separation prove the material ablation process spectral lines. The innermost plasma for a microstructuring process using picosecond double pulses. and the online diagnostics of the plas- zone has an excitation temperature of Below: Intensity distribution ma dynamics without increasing the around 12,000 K, which decreases to of an Fe II spectral line (λ = laser energy input. One approach around 7,000 K nearer the outer edges. 261.76 nm) in plasma. The involves dividing the energy of the ion line is most intense in the innermost plasma zone (E = discrete laser pulses into pulse bursts b 2 mJ, ∆t = 1 µs, tint = 1 µs). with interpulse separations in the nano- second or microsecond range. This has Contact the effect of conditioning the surface of the sample and the processing envi- Dipl.-Ing. (FH) C. Hartmann, Tel.: -207 ronment. [email protected] Dipl.-Phys. C. Gehlen, Tel.: -127 [email protected] Dr. A. Gillner, Tel.: -148 [email protected] Dr. R. Noll, Tel.: -138 [email protected]

Fraunhofer ILT Annual Report 2006 121 Single particle analysis for the separation of minerals during the extraction of primary raw materials - EIGER

The project goal is to build a pilot-scale Task demonstrator capable of testing the functionality of the sorting process The low price of construction materials under close-to-real-life conditions. and bulk natural raw materials such as limestone makes it uneconomical to transport them over long distances. The site where they are extracted and Results and Applications processed has to be as close as possible to the end consumer. After extraction The sorting process is initially being from the natural deposit, the mineral tested on limestone and dolomite, of economic value usually has to be or minerals with a high MgO content, separated from inferior accessory and and the results are being validated inter-grown rock. However, because using typical samples from a variety traditional separation methods are not of natural deposits. The requirements always suitable, a R&D project has for industrial application are that the been set up to develop a novel, laser- system should achieve a mass through- assisted sorting process that operates put of 150 t/h with a yield of 90 - 95 economically and automatically and percent and a product purity of > 95 can be used to characterize and sort percent. solid primary raw materials according to the elements they contain, directly In the second stage of the project, after extraction. The project entitled LIBS experiments have been conducted EIGER is a collaborative effort being on static MgO reference samples and conducted by a consortium of two on limestone and dolomite samples research institutes and six small and extracted from quarries in Hastenrath, medium-sized enterprises. Kornelimünster and Iran. The focus of these experiments lay on the influence of the laser pulse energy, variations in the number of pulses within a laser Above: UV-illuminated mineral sample with tungsten content Method burst, and the evaluation of single revealed by fluorescence. event spectra, and furthermore the Below: Cross-section through The approach developed for rapid spatial separation of the laser beam the same mineral sample show- identification and sorting of the raw and the effect of wetness on the mea- ing inhomogeneous tungsten layers. material combines image processing, surement results. laser geometry measurement, and a sensor system based on the use of The project is being conducted with laser-induced fluorescence and break- the financial support of the BMWA, down spectroscopy. After reducing and the participating SMEs and the Fraun- fractionating the material, its geome- hofer-Gesellschaft. trical-optical characteristics are recorded and analyzed using image processing algorithms. In the next step, the che- mical composition of the single parti- Contact cles is determined by laser spectros- copy. Finally the material is ejected, Dipl.-Phys. Ü. Aydin, Tel.: -431 separated into two or more fractions [email protected] on the basis of selection criteria de- Dr. R. Noll, Tel.: -138 rived from the entire set of measured [email protected] values.

122 Fraunhofer ILT Annual Report 2006 Characterization of ultrafine dust particulates in industrial process emissions

Task Results and Applications

Air pollution with fine and ultrafine Preliminary results of tests conducted dust particulates has recently become on emissions from steel factories indi- recognized as one of the main public cate, for example, an elevated content health risks. Significant sources of an- of lead, cadmium and copper in parti- thropogenic particulates are vehicular culates of up to 100 nm in diameter, traffic and industry. whereas higher concentrations of other metals appear to be found in larger Extremely small nanoscale particulates particulates. In other words, the che- represent an elevated health risk be- mical composition appears to vary as a cause their size allows them to pene- function of the size of the particulates, trate the furthest into the human or- allowing a correlation to be drawn ganism. At the same time, these aero- with the health risk associated with sol particulates are the most difficult the different types of emission. for measuring instruments to detect, hence the pressing need for further re- The results of the project will be used search. This project concerns a method to develop emission-reduction strategies Above: Particulates collection for determining the composition of for the industrial plants under study. methods based on impactors particulates, with particular emphasis The method can also be employed uni- with thin sheets of aluminum. on the concentration of heavy metals. versally in other branches of industry, The dark areas with a diameter of < 1 mm indicate accumulations engine development and nanotechno- of particulates. logy. Below: Laser spectroscopy me- thods can be used to analyze Method The project receives financial support both particulates collected on filters and airborne particulates. from the European Union’s Research Two methods of measurement are Fund for Coal and Steel (RFCS) and the being developed on the basis of laser- Fraunhofer-Gesellschaft. induced breakdown spectroscopy for the chemical analysis of the particu- lates. In the first method, the particu- lates are collected on filters, classified Contact by size, and then analyzed in the labo- ratory. In the second method, single Dr. C. Fricke-Begemann, Tel.: -196 particulates are analyzed onsite, directly [email protected] in the air stream. This latter method Dr. R. Noll, Tel.: -138 also permits rapid online characteriza- [email protected] tion.

To obtain reliable measurement results, it is necessary to produce samples and aerosols that enable the test instru- ments to be calibrated for all relevant elements over a range of concentra- tions that varies by several orders of magnitude.

Fraunhofer ILT Annual Report 2006 123 Remote analysis using laser-induced breakdown spectroscopy - TeleLis

Task Results and Applications

Laser-induced breakdown spectroscopy TeleLis is a mobile analysis system is a versatile analytical method that can of compact design, capable of being be used to measure the elemental quickly focused on the target object. composition of gases, liquids, solids A pilot laser beam and an autofocus and dust quickly and accurately with- feature help to find the correct position out physical contact. This direct form with respect to the target. of laser analysis is used in environmen- tal engineering (e.g. water and air qua- For ease of transport, the system is lity), steel manufacturing (process mo- mounted on a trolley that also protects nitoring, quality assurance), metalwork- the equipment against environmental ing (seam tracking, verification in- disturbances such as jolting or splash- spection), biomedicine, the detection water. A monitoring system surveys the of explosives and hazardous chemicals, operation of all TeleLis components and and art restoration. Many of these ap- logs the system status by means of plications call for a mobile system to control software. enable field use and measurement over long distances. The system can record either full spec- tra at a frequency of 1 Hz or individual spectral lines at 10 Hz. Analysis can be performed using both single and Method double pulses, enabling element con- centrations down to 0.1% and lower A flash-lamp-pumped solid-state laser to be detected. is expanded by a telescope and auto- matically focused on the target up to TeleLis is ideally suited for applications 12 m away. The generated plasma where it is impossible or impractical to light is guided via a coaxial large aper- access the measurement object directly, Above: A TeleLis system ready to perform measurements. ture telescope to a CCD spectrometer for example when measuring concen- Below: Calibration curve for the providing continuous spectral analysis trations of hazardous chemicals. magnesium content in aluminum in the 175 - 520 nm range. The system alloys, measured at a distance of 5 m. The low spread of the data can be swiveled vertically and horizon- points enables quantitative mea- tally through ± 45º and folded up for surements to be obtained even at transport. Contact a considerable distance. Dipl.-Ing. (FH) A. Lamott, Tel.: -133, [email protected] Dr. R. Noll, Tel.: -138, [email protected]

124 Fraunhofer ILT Annual Report 2006 Optical stand-off detection of explosives and improvised explosive devices (OFDEX)

Task Results and Applications

Terrorist attacks have been on the rise Initial tests carried out on ammonium for the past several years, particularly nitrate, one of the main components in the form of car and suitcase bombs. of ANFO explosives, show that laser- So far, there is no system available that induced breakdown spectroscopy can can detect such »improvised explosive help to detect small amounts of nitro- devices« (IEDs) from a safe distance. gen-containing compounds over a distance of 5 meters, even in the pre- Furthermore, there is a great demand sence of atmospheric nitrogen. in the civil and environmental protec- tion sector for systems capable of re- The project is being implemented with mote chemical analysis. These could the financial support of the Fraunhofer- help to monitor emissions or provide Gesellschaft. assistance when dealing with accidents involving hazardous chemicals, for example in the petrochemical industry.

Contact Detection of ammonium nitrate over a distance of 5 m. Dr. P. Jander, Tel.: -440 Method [email protected] Dr. R. Noll, Tel.: -138 Four Fraunhofer Institutes have joined [email protected] forces to develop a system for the stand-off detection of hazardous and explosive materials, based on several optical methods that complement one another.

The Fraunhofer ILT, for its part, is using laser-induced breakdown spectroscopy, a technique which enables high mea- surement frequencies and allows the elemental composition of a material to be determined precisely even over a distance of several meters.

On the basis of experience gained by the Fraunhofer ILT in laser analysis over distances of up to 12 meters, the re- searchers are developing methods and data analysis algorithms that will allow them to detect the slightest traces of explosives even over distances of up to 50 meters.

Fraunhofer ILT Annual Report 2006 125 Confocal laser-scanning microscopy with multiphoton excitation

Task Results and Applications

Confocal laser-scanning microscopy Confocal microscopy is used at the has become established as a versatile Fraunhofer ILT primarily where there is measuring technique for the optical a need to detect weak signals with a analysis of fluorescence-tagged or re- high signal-to-noise ratio in femtoliter flective samples in high spatial resolu- volume samples. Penetration into dee- tion. It is used primarily for examining per organic layers is limited due to cells and tissue. By treating specific scattering and absorption of the emit- parts of the sample with fluorescent ted fluorescence. Ultra-short pulses in dyes and scanning it at several diffe- the femtosecond range and the asso- rent wavelengths simultaneously, it is ciated high photon densities permit possible to obtain structural and func- the excitation of multiphoton proces- tional information with an extremely ses in the laser focus, so that fluores- high spatial resolution. cence can only occur at those points. This effectively suppresses bleaching of the sample. Since infrared radiation is not so widely scattered, this method Method allows even deeper-lying tissue layers to be examined. The high spatial resolution is achieved by using lenses with a high numeric aperture (NA = 1.4) and mapping the measuring signal on a pinhole aperture Contact with a diameter of only a few micro- meters in the image plane. High-speed Dipl.-Phys. T. Schwendt, Tel: - 436 galvanometric scanner mirrors redirect [email protected] the laser beam with a 2 kHz line fre- Dr. R. Noll, Tel.: -138 quency to generate two-dimensional [email protected] Above: Directly diode-pumped femtosecond laser for the exci- microscopic images. High-resolution tation of multiphoton processes. three-dimensional images can be ge- The laser developed at the nerated with the aid of a z-scanner Fraunhofer ILT is compact and that axially displaces the position of easy to use. Below: Fluorescence image of the scanning laser focus. A new-gene- triple-dyed fibroblasts (connec- ration laser scanning microscope incor- tive tissue cells) generated with porates a direct diode-pumped femto- three excitation wavelengths. λ = 488 nm, actin filaments second laser developed at the Fraun- (blue), λ = 543 nm, mitochon- hofer ILT, making it possible to excite dria (green), λ = 633 nm, cell dyes in the UV range with multiphoton nucleus (red). processes. In this way, microscope examinations of deep tissue layers or strongly scattering tissue can be per- formed.

126 Fraunhofer ILT Annual Report 2006 Optical coherence tomography (OCT) in intraoperative tissue diagnostics

Task Results and Applications

Optical coherence tomography (OCT) In a series of validation experiments, is an imaging technique which allows cross-section images were taken of high-resolution 3-D tomography vessels inside a tissue sample. The images to be created during surgery. images were made by moving the Based on interferometric measure- sample on a microscope stage below ments, this technology permits the de- the measuring beam. A clear contrast tection of structures with a depth reso- could be observed between the vessels lution of just a few micrometers. The and the tissue surrounding them. With penetration depth lies at about 5 mm, the help of a software program speci- depending on the tissue being exa- ally developed for OCT diagnosis, the mined. In the medical field, OCT is measurement data can be displayed used as a marker-free, diagnostic tech- either as 2-D sections or 3-D objects. nique for distinguishing morphologi- Image sequences can be used to eva- cally between different types of tissue. luate changes in the vessels' geometry, 10 mm One specific area of application is the for example after thermal interaction detection and measurement of blood due to irradiation with laser light. vessels more than 50 µm in diameter, so that the cauterization of such vessels In addition to medical applications, by laser coagulation can be monitored optical coherence tomography is also during surgery. used in production engineering. It is particularly well suited to measuring the thickness of films on glass and plastic parts, due to its high axial reso- Method lution and wide measurement range. Films more than 20 µm thick can be The OCT system's beam source is a measured accurately to within 1 µm. super-luminescence diode with an This requires only the smallest of diffe- Above: Cross-section image emission wavelength of λ = 1300 nm. rences in the refractive index at the of a blood vessel taken with For an interoperative diagnosis, the interface between two consecutive the OCT measuring system in measuring beam is coupled into an en- layers. a pig's heart; vessel diameter doscope via an optical fiber and focused 650 µm. Below: OCT image of a three- on the tissue to be examined. The layer plastic laminate system. beam sweeps the surface of the tissue, The middle layer is 270 µm thick, performing a deep scan at 200 diffe- Contact and the total thickness of the composite material is 4.1 mm. rent measuring points each second with an axial optical resolution of appro- Dipl.-Phys. S. Hölters, Tel.: -436 ximately 10 µm. This is equivalent to [email protected] a digital resolution of 3000 pixels per Dr. R. Noll, Tel.: -138 deep scan. The OCT system has an axial [email protected] measurement range of about 9 mm in air, but is reduced to approximately 2 mm in tissue due to light absorption.

Fraunhofer ILT Annual Report 2006 127 Integrated microfluidic diagnostic systems - IMIKRID

single-molecule events to be reprodu- Task cibly triggered at the sensors and the signal responses to be tested. A further In the interdisciplinary joint project function of the single-molecule detector IMIKRID, researchers will develop and is to position nanoscopic receptor sen- validate a novel technological platform sors in the microfluidic system and for the development of custom-built measure the specific bonding of in- integrated systems for in-vitro diagnos- dividual analyte molecules at these tics offering an extremely high degree sensors. This will optimize the flow of sensitivity (10-12 bis 10-13 mol/l). behavior of the fluid and keep analysis times short.

Method Results and Applications The key component of this diagnostics platform is a microfluidic chip with cir- Illnesses with a high mortality rate, cular-flow micro-channels that conduct such as cancer and cardiovascular a solution containing the analyte mole- diseases, can be treated successfully if cules to be detected. Inside the micro- they are caught at an early stage. By channels of the silicon chip there are developing an improved early-diagno- four independent single-molecule-sen- sis system based on molecular markers, sitive biosensors, each based on a dif- which are present in very small con- ferent sensor technology. Three of the centrations in blood serum, patients’ sensors employ electrochemical mea- chances of recovery and quality of surement techniques, while the fourth life can be significantly increased. The uses fluorescence to detect the analytes. IMIKRID detection system currently All of the sensors have nanoscopic being developed for this purpose can transducer surfaces coated with speci- diagnose marker concentrations in the fic receptor molecules that bind with single-molecule range down to below the analytes. Specific bonds made by 10-12 mol/l. the transducers can be detected either by electronic amplification (seFET), en- The R&D activities of the IMIKRID zymatic catalysis (nano-enzyme elec- project are supported by the German trodes), measuring of redox potential Federal Ministry of Education and (cyclic voltametry) or fluorescence Research (BMBF) and are being imple- (micro-optical fluorescence sensor), mented together with partner institutes depending on which sensor technique of the Fraunhofer-Gesellschaft and the Above: A microfluidic sensor chip with electrochemical sen- is used. Multifunctional nanoparticles Institute for Micro Sensors in Erfurt. sors, data processing electronics act as signal amplifiers in the process, and a micro flow cell, with directionally coupled receptor Source: Fraunhofer Institute for Applied Information Technology molecules and transducers with a high FIT, Biomolecular Optical Sys- quantum yield or a high redox poten- Contact tems department. tial. In the IMIKRID project, the Fraun- Below: Confocal detection sys- hofer Institute for Laser Technology ILT Dr. A. Lenenbach, Tel.: -124 tem for single-molecule diag- nostics with an optical interface is developing a confocal single-mole- [email protected] for integrating optical tweezers. cule detector with integrated optical Dr. R. Noll, Tel.: -138 Diffusion-based detection limit tweezers that can be used to move nano- [email protected] for fluorescence-tagged biomo- lecules in solution at concentra- scopic sensors with sub-micrometer ac- tions of c = 10-11 mol/l. curacy towards the transducer surfaces with which they interact. This allows

128 Fraunhofer ILT Annual Report 2006 MultiLas - a laser endoscope for the multimodal treatment of brain tumors

tissue, and optical coherence tomo- Task graphy (OCT) to detect and measure blood vessels. The plasma glow gene- MultiLas is an endoscope designed for rated during tissue ablation helps to the minimally invasive local treatment monitor the focus of the ablation laser of intracranial tumors through keyhole relative to the tissue. Fluorescence ex- surgery. By employing five different ra- citation takes place at 405 nm, while diation sources in a single endoscope, optical coherence tomography is car- brain tumors can be ablated accurate- ried out at 1300 nm. ly, blood vessels can be cauterized and micro-metastases can be selectively destroyed by means of photodynamic therapy (PDT). Results and Applications

The MultiLas endoscope technology Method was developed in a collaborative pro- ject together with several small and MultiLas operates on the basis of an medium-sized companies. In addition, endoscope with a micro-optical chan- the fluorescence diagnostics and OCT nel 2.7 mm in diameter which guides technique were successfully validated the therapeutic and diagnostic laser using in-vitro models in combination beams into the surgical cavity. The with the endoscope. On the basis of measuring radiation generated in the their fluorescence, cells were detected surgical cavity to monitor the therapy down to single-cell level, and geome- process is gathered by the same micro- tries of vessels 300 µm to 700 µm in optical channel and mapped onto a diameter were displayed. In a separate detection system. Tumors with a maxi- test configuration, coagulation experi- 50 µm mum diameter of 50 mm are ablated ments were carried out under the from the center to the perimeter with opto-mechanical boundary conditions Above: Endoscope of the Multi- a picosecond laser (Ep = 2 mJ, λ = of the laser endoscope in order to eva- Las demonstrator with an outer 532 nm, f = 10 kHz). The ablated frag- luate suitable coagulation parameters. diameter of 5.5 mm. Inside it ments of tissue are removed from the there is a micro-optical channel surgical cavity by a rinsing and suction The development of MultiLas is sup- and a rinsing and suction sys- tem for removing ablated tissue system integrated in MultiLas. Prior ported by the German Federal Ministry from the surgical cavity. The five to ablation, a continuous laser beam of Economics and Technology and therapeutic and diagnostic laser source (P = 30 W, λ = 1064 nm) cau- is being implemented together with beams are guided into the sur- gical cavity via the micro-optical terizes the blood vessels supplying the a clinic and several industry partners. channel. tumor by means of laser coagulation Below: Image of cultivated glio- to preclude internal hemorrhaging. To ma cells taken by the MultiLas ensure that endoscopic tumor therapy fluorescence module. Thanks to their fluorescence signal (green is safe and precise, it is essential that Contact to red), individual cells can be both ablation and coagulation be re- clearly distinguished from the liably monitored online. This is done Dr. A. Lenenbach, Tel.: -124 background (shown in dark blue). This single-cell sensitivity using fluorescence diagnostics to dis- [email protected] allows tumors to be detected tinguish between cancerous and healthy Dr. R. Noll, Tel.: -138 on a scale of approx. 30 µm. [email protected]

Fraunhofer ILT Annual Report 2006 129 Endoscopic laser coagulation system for the intraoperative cauterization of blood vessels

well as helping to identify blood vessels, Task OCT can also be used to verify success- ful cauterization. This information is During endoscopic surgery, blood ves- provided by a series of cross-sectional sels must be cauterized prior to tran- images taken along the length of the section in order to prevent internal coagulation zone. hemorrhaging. To this end, the Fraun- hofer Institute for Laser Technology is developing a laser coagulation system which allows endoscopic, contact-free Results and Applications cauterization of blood vessels. The laser coagulation system was vali- dated in a series of trials during which the most suitable coagulation parame- Method ters for a range of blood vessels were established. This was achieved by vary- 1 mm An Nd:YAG laser with an emission wave- ing the length of exposure to radiation, length of λ = 1064 nm and a maxi- the intensity of the radiation and the mum cw output power of P = 28 W is size of the irradiated area. The trials employed for laser coagulation. During were carried out ex vivo on the vascular minimally invasive surgical procedures, system of a porcine heart. The vessels the laser can be introduced into the were filled with a native BSA solution surgical cavity with the help of an en- with a normal protein concentration. doscope tube. The laser beam itself is Normal circulatory pressure was main- focussed onto the vessel to be caute- tained in the blood vessels during the rized by means of a short-focal-length trials. With the help of the ex vivo trials, lens mounted on the tip of the endos- a »therapeutic window« could be 1 mm cope. The success of laser coagulation identified in which laser coagulation relies on the optimization of a number resulted in reliable cauterization of of parameters depending on the dia- the vessel concerned. As not only the Above: Interferogram of a blood vessel before coagula- meter of the blood vessel to be caute- geometry of the vessel, but also blood tion, diameter of the vessel rized and the rate of blood flow within pressure and the rate of blood flow in 700 µm. the vessel. The most important para- the vessel have an important influence Below: Interferogram of meters determining successful coagu- on the success of cauterization, the the same blood vessel after successful laser coagulation. lation are the length of time the tissue effect of heat dissipation in the inter- is exposed to radiation, the power action zone is also being systematically density of the radiation and the geo- investigated. On the basis of the results metry of the area to be irradiated. obtained in such trials, a database of The diameter of the thermal interaction coagulation parameters for particular zone can, for instance, be adjusted by types of blood vessels is to be established. varying the distance between the focal position of the lens and the surface of the blood vessel, depending on the diameter of the vessel. Contact

Optical coherence tomography (OCT) Dr. A. Lenenbach, Tel.: -124 is employed to determine the exact [email protected] location and diameter of blood vessels. Dr. R. Noll, Tel.: -138 This procedure allows the identification [email protected] of vessels that are hidden several milli- meters below the tissue surface. As

130 Fraunhofer ILT Annual Report 2006 Application system for intracranial photodynamic therapy - PDT

Task Results and Applications

Despite surgical intervention and radio- To evaluate suitable radiation parame- therapy, the prognosis for patients suf- ters for PDT on gliomas, a module was fering from aggressive brain tumors, developed that allowed in-vitro PDT such as malignant gliomas, is generally experiments to be carried out on culti- poor, with average life expectancies vated glioma cells. The radiation mo- Dose-response curve for parallel radiation mode and continuous time regime of less than one year. Photodynamic dule is subject to the same opto-me- therapy (PDT) promises to improve chanical constraints as the endoscope the effectiveness of the treatment of that will later be used to carry out the gliomas. The therapy is based on the therapy. PPIX was chosen as photosen- y t i l

administration of a photosensitizing sitizer for the trials. This substance is a t i v l agent that selectively accumulates at synthesized in glioma cells after the ex- l e higher concentrations in tumor cells tracellular administration of 5-aminole- C and has a cytotoxic effect when exposed vulinic acid (5-ALA) and has already to light of a particular wavelength. proved successful in the clinical treat- ment of gliomas. In line with clinical practice, 5-ALA was administered to Dose the cells 3 hours before irradiation. The Method experiments were designed to estab- lish the relationship between phototo- An endoscope is being developed to xicity and the radiation dose. Factors carry out PDT on malignant cerebral glio- such as the temporal distribution and mas. With its help, tumor tissue can be the intensity of the dose were consi- irradiated with laser light during a mini- dered. The largest therapeutic effect mally invasive surgical procedure. The was achieved with moderate intensities endoscope is controlled by a stereotactic of around 400 mW/cm2 and a dose of guidance system that utilizes CT data 3 J/cm2. This resulted in a cell mortality to precisely locate the target tissue mass. rate of 100 %. Above: Dose-response curve for The inoperable macroscopic remains of experiments conducted on L18 tumors or microscopic metastases infil- glioma cell cultures with conti- trating healthy tissue can then be de- nuous radiation of 400 mW/cm2 stroyed with the help of a laser beam Contact and radiation doses between 0.5 J/cm2 and 3 J/cm2. Radiation with an emission wavelength of λ = 635 dose for a cell mortality rate of 2 nm that is coupled with the micro-optical Dr. A. Lenenbach, Tel.: -124 50 %, LD50 = 1.2 J/cm , radiation system of the endoscope. The irradiation [email protected] dose for a cell mortality rate of 2 90 %, LD90 = 2.9 J/cm . of the tumor tissue can be carried out Dr. R. Noll, Tel.: -138 Below: Radiation module for with either focused or divergent laser [email protected] PDT experiments on glioma cell light. The laser beam is reflected onto cultures installed below a sterile the tissue to be irradiated by a deflection workbench, therapeutic wave- length λ = 633 nm. mirror mounted on the tip of the endos- cope at 90° to its longitudinal axis. By rotating the mirror around the axis of the endoscope, altering the depth of the probe position or adjusting the front lens, the laser beam is capable of scann- ing target tissue in three dimensions.

Fraunhofer ILT Annual Report 2006 131 A rational approach to protein crystallization based on optical measuring techniques

Task Results and Applications

The culture of protein crystals is a pre- A demonstrator for measuring scattered requisite for investigating the structure light in small sample volumes was of proteins using single-crystal X-ray built. In addition to three precision diffraction. Establishing the optimal axes for accurately positioning the conditions under which crystallization measuring point in a small sample can take place is a time-consuming volume (typically 500 nl), it incorpo- and labor-intensive process that pre- rates a system of lenses for measuring sents a major impediment to the pro- scattered light and a second system gress of investigative work on protein of lenses for polarization microscopy. structures. The Fraunhofer Institute This enables all phases of crystallization for Laser Technology collaborated with to be investigated. Static scattered research and industry partners to deve- light measurements display the poten- lop a demonstrator that enables the tial for thermodynamic interaction be- systematized culture of single protein fore the start of nucleation, dynamic crystals. light-scattering techniques make it possible to observe the nucleation pro- cess, and polarization microscopy can provide high-contrast imaging of the Method precipitates or crystals after crystalliza- tion or precipitation has taken place. The demonstrator built at the ILT ena- It is possible to distinguish between bles static and dynamic measurements microcrystalline and amorphous pre- of scattered light in protein solutions cipitates. All system components and to be performed on small volumes. The automated series of measurements can measurement of static light scattering be computer-controlled with the help provides information about the inter- of specially developed software. The action of dissolved proteins in the demonstrator is currently being evalua- Above: Demonstrator for protein crystallization with an solution, while the measurement of ted in the applications laboratory of a automated pipette system for dynamic light scattering, by analyzing partner institute where the systematic preparing samples. particle movement within the solution, crystallization and investigation of a Below: Optical systems for po- yields information about the size of variety of proteins is being undertaken. larization microscopy and light scattering beneath the sample the proteins and reveals aggregation carrier. processes. The sample carrier in which The work was funded by the German the measurements are performed can ministry of economics, several SMEs be filled by an automated pipette sys- and the Fraunhofer-Gesellschaft. tem, permitting a high throughput and minimum wastage during the measur- ing process. The optical measuring techniques provide objective evaluation Contact data that correlate to the probability of crystallization. This data allows the Dr. C. Janzen, Tel.: -124 most favorable solution parameters [email protected] for crystallization (pH value, salt con- Dr. R. Noll, Tel.: -138 centrations, additional and precipitation [email protected] reagents etc.) to be more effectively determined than was previously possible.

132 Fraunhofer ILT Annual Report 2006 Patents

Patents Germany Patents Europe Patents USA Patent Applications National Verfahren zum Bohren von Verfahren und Vorrichtung Method and Device for metallischen Werkstoffen sowie zum Bearbeiten von Werkstücken Producing Extreme Ultraviolet Verfahren und Vorrichtung von geschichteten metallischen mit Laserstrahlung Radiation and Soft-X-Ray Radiation zur Vermessung geometrischer Werkstoffen und solchen, die EP 1 047 522 B 1 US 7, 126, 143 B 2 Merkmale von Objekten mit mindestens eine keramische Schicht robotergeführtem Lasersensor aufweisen Verfahren und Vorrichtung Method and Device for the 10 2006 016 677.9-54 DE 10 2004 014 820 B 4 zur Oberflächenbehandlung von Generation of Far Ultraviolet Objekten or Soft-X-Ray Radiation Vorrichtung und Verfahren Verfahren für die Material- EP 1 337281 B 1 US 6, 967, 341 B 2 zum Fügen von wenigstens zwei bearbeitung und Verwendung aus thermoplastischem Material DE 100 29 110 B 4 Strahlführendes und/oder frequenz- bestehenden Fügepartnern konvertierendes optisches System mittels Laserstrahlung Verfahren zum Aufbau mikro- sowie Verfahren zur Herstellung Patents China 10 2006 008 776.3-16 optischer Bauteile EP 1 476 776 DE 102 50 074 B 4 Verfahren und Vorrichtung zum Flexibler Laserapplikator Verfahren zum Glätten und Polieren Erzeugen von Extrem Ultraviolett 10 2006 039 471.2-51 Vorrichtung und Verfahren zum von Oberflächen durch Bearbeitung und weicher Röntgenstrahlung Positionieren und Bestücken eines mit energetischer Strahlung ZL 02807601.X Erhöhung der Präzision von Bauelementes in Oberflächen- EP 1 516 068 B 1 Handhabungssystemen durch Montagetechnik Feinpositioniereinrichtung DE 199 48 455 B 4 Laser-Materialbearbeitung 10 2006 049 627.2 mit hybriden Prozessen Patents South Afrika Verfahren sowie Düse zur EP 1 497 071 B 1 Bearbeitung oder Analyse eines Verfahren und Vorrichtung Werkstücks oder einer Probe mit Patent Applications zur Durchführung einer Plasma- einem energetischen Strahl International emissionsspektrometrie DE 10 2004 018 280 B 4 2004/10314 Verfahren und Vorrichtung Montage von Kühlkörpern zur Vermessung der lateralen an Laserkristallen Relativbewegung zwischen DE 102 26 724 B 4 International trademark Bearbeitungskopf und Werkstück bei der Bearbeitung mit einem Frequenzkonvertierte Laser- Bearbeitungsstrahl TECHNOLOGIE BUSINESS TAG TBT anordnungen PCT/DE2006/000775 DE 195 36 880 B 4 900 662 Verfahren zur Vermessung von Verfahren zur Modifizierung Phasengrenzen eines Werkstoffes von Materialeigenschaften bei der Bearbeitung mit einem DE 102 32 815 B 4 Bearbeitungsstrahl sowie zuge- hörige Vorrichtung Kompakte UV-Barrieren- PCT/DE2006/000400 entladungslampe DE 10 2005 007 370 B 3 Vorrichtung zum Bohren und für den Materialabtrag mittels Drehdurchführung Laserstrahl für ein Gas-Pulver-Gemisch PCT/EP2006/001964 DE 10 2005 025 027 B 3 Einbringen von Mustern in matte Vorrichtung zum Bohren und Oberflächen durch moduliertes für den Materialabtrag mittels Laserstrahlpolieren Laserstrahlung PCT/DE2006/000776 DE 10 2005 047 328 B 3

Fraunhofer ILT Annual Report 2006 133 Dissertations Diploma Theses

Kelbassa, I. - 13.01.2006 Bankowski, Max Gummersbach, Max Instandsetzung von Flugtriebwerks- Herstellung und Untersuchung Beschichten dünner Bleche mit dem komponenten mittels Laserstrahl- von Gradientenschichtwerkstoffen Mikro-Laserstrahl-Auftragschweißen Auftragschweißen für den Einsatz im Werkzeugbau Hack, Sebastian Uckelmann, I. - 31.01.2006 Bao, Danxia Polieren mit Laserstrahlung zur Generative Serienfertigung von Laserunterstützte Fixierung von Erzeugung von Design-Oberflächen individuellen Produkten aus CoCr Kollagen Matrices mit dem selektiven Laserschmelzen Hermes, Viktor Broder, Silke Defektfreies Beschichten von y-TiAl Klages, K. - 12.05.2006 Entwicklung und Validierung einer durch Laserstrahl-Auftragschweißen Laserstrahl-Mikroschweißen unglei- Bestrahlungssonde für die intrakra- cher Metalle durch Nahtschweißen nielle Photodynamische Therapie Hoeges, Simon mit gepulsten Nd:YAG-Lasern Modelltheoretische und experimen- Buerger, Andreas telle Untersuchung der Dynamik Russek, U.-A. - 23.05.2006 Verbesserung der Umformbarkeit kleiner Schmelzbäder Prozesstechnische Aspekte schwer umformbarer Werkstoffe des Laserdurchstrahlschweißens durch lokale Laserbestrahlung Kappler, Jochen von Thermoplasten Grundlegende Untersuchungen Dolkemeyer, Jan zum Laserstrahl-Auftragschweißen Moiseev, L. - 05.07.2006 Auslegung und Konstruktion von Ti-6Al-4V mit Nd:YAG-Laser- Pulsed Laser Deposition von eines Laseroszillators zur Charakte- strahlung Er:ZBLAN-Schichten für den risierung von ytterbiumdotierten Aufbau eines integrierten Kristallen Leonhardt, Judith Wellenleiterlasers im grünen Messung der Lichtausbreitung Spektralbereich Emmerich, Andreas in biologischem Gewebe und an Entwicklung einer Faserkühlung Gewebsphantomen (Bachelor Arbeit) Giesekus, J. - 14.07.2006 für einen Hochleistungs-Faserlaser Diodengepumpte Laserverstärker Masberg, Kai Ullrich mit flachen Lasermedien Erben, Benjamin Untersuchung der Fügezone von Untersuchungen zur Leistungs- Preform und SLM-Bauteil aus dem kopplung von Hochleistungs- Werkstoff 1.2343 Diodenlasern mittels faserintegrier- ter Komponenten Pietrusky, Marco Laserstrahl-Mikroschweißen mit Ewering, Mara Faserlaserstrahlung Prozessqualifizierung des Laserstrahllötens von Aluminium- Schloemer, Philipp Stahl-Verbindungen an Versuchs- Aufbau und Entwicklung einer karosserien inversen Auflicht-Dunkelfeldoptik für Streulichtmessungen an Protein- Fiedler, Wolfgang lösungen Prozesskontrolle beim Hochge- schwindigkeitsschweißen von Simon, Oliver dünnwandigen Aluminiumrohren Untersuchung des Einflusses von aktiv temperierten Optiken auf die

Fraas, Christian Strahlausbreitung von CO2-Hoch- Entwicklung und Evaluierung eines leistungslasern Sensors zur optischen Messung der Relativgeschwindigkeit zwischen Vedder, Christian Werkstück und Bearbeitungskopf Beitrag zur Verfahrensentwicklung bei der Materialbearbeitung mit des Selektiven Reaktions-Lasersin- Laserstrahlung terns für die generative Herstellung von Bauteilen aus Spinelkeramik Gehlen, Christoph Dominic Prozessdiagnostik laser-induzierter Waehler, Tobias Plasmen beim präzisen Mikro- Laserstrahlpolieren von schrägen Materialabtrag mit Pulsgruppen Ebenen und Nuten

Grimm, Stefan Werner, Marcel Entwicklung eines konfokalen Untersuchung alternativer Kühltech- Laserscanning Fluoreszenz-Endos- niken für Hochleistungsdiodenlaser kops für die In-vivo-Tumordiagnostik im Gehirn Westphalen, Thomas Untersuchung von Hochleistungs- Diodenlaserbarren mittels Einzel- emitteraufgelöster Charakerisierung

134 Fraunhofer ILT Annual Report 2006 Scientific Publications

N. C. Stache, H. Zimmer, J. Gedicke, K. Walther, M. Brajdic, E. W. Kreutz J. Gedicke, B. Regaard, A. Gillner, B. Regaard, A. Olowinsky, A. Knepper, Enhanced processing speed in S. Kaierle T. Aach laser drilling of stainless steel Kontrolle beim Mikroschweißen Approaches for High-Speed Melt by spatially and temporally - Automatisierte Prozessüber- Pool Detection in Laser Welding superposed pulsed Nd:YAG laser wachung durch koaxiale Applications radiation Prozesskontrolle mit Fremdbe- Proceedings of VMV 2006 The International Journal of Ad- leuchtung 8 Seiten, 2006 vanced Manufacturing Technology Laser Technik Journal 4 5 Seiten, 2006 5 Seiten , 2006 Ü. Aydin, R. Noll, J. Makowe Automatic sorting of aluminium M. Leers, C. Scholz, K. Boucke, E. W. Kreutz, J. Willach, I. Kelbassa, alloys by fast LIBS identification R. Poprawe S. Keutgen, R. Poprawe 7th International Workshop Expansion-matched passively- Laser Technologies for Progress in Analytical Chemistry cooled heatsinks with low thermal Manufacturing and Repair in the Steel and Metal Industries resistance for high-power diode of Rotating Machinery Power Ed. J. Angeli laser bars Plant Components Seiten 309-314, 2006 Proceedings of SPIE 6104 Proceedings of ISROMAC Seiten 610403.1-610403.10, 2006 8 Seiten, 2006 D. Petring Combined cutting and welding: R. Wester, R. Noll I. Kelbassa, A. Weisheit, Laser beam quality enhances Fast characterisation of steel K. Wissenbach, V. Hermes process efficiency and flexibility Cleanness by Advanced Mathe- Laser metal deposition Tagungsband-CD zum 2. Inter- matical Analysis of Spark and of TiAl alloys nationalen Workshop »Faserlaser« Laser Source Optical Emission Proceedings of PICALO 2 in Dresden Data 5 Seiten, 2006 34 Seiten, 2006 7th International Workshop Progress in Analytical Chemistry E. Haberstroh, W.-M. Hoffmann, J. Gedicke, B. Regaard, K. Klages, in the Steel and Metal Industries, R. Poprawe, F. Sari A. Olowinsky, S. Kaierle Ed. J. Angeli Laser transmission joining Comparison of different process Seiten 209-212, 2006 in microtechnology monitoring methods for laser Microsystem Technologies beam micro welding D. Petring Seiten 632-639, 2006 Proceedings of ICALEO 25 Flexibles Laserschneiden und 8 Seiten, 2006 -schweißen von Blechbaugruppen A. Löbe, J. Vrenegor, R. Fleige, ohne Werkzeugwechsel V. Sturm, R. Noll C. Scholz, K. Boucke, R. Poprawe, Tagungsband-CD zum Aachener Laser-induced ablation of a steel M. T. Kelemen, J. Weber, M. Mikulla, Kolloquium für Lasertechnik AKL'06 sample in different ambient G. Weimann 22 Seiten, 2006 gases by use of collinear multiple Comparison between 50 W laser pulses tapered laser arrays and tapered H. Bette, R. Noll Analytical & Bioanalytical Chemistry single emitters High-speed, high-resolution LIBS Vol. 385, No. 2 Proceedings of SPIE 6104 using diode-pumped solid state Seiten 326-332, 2006 Seiten 61040G.1-61040G.8, 2006 lasers Laser-Induced Breakdown R. Noll, U. Panne C. Wessling, M. Traub, D. Hoffmann, Spectroscopy (LIBS): Fundamentals Laser-induced breakdown R. Poprawe and Applications spectroscopy - EMSLIBS 2005 Dense wavelength multiplexing Seiten 490-515, 2006 Analytical & Bioanalytical Chemistry for high power diode laser Vol. 385, No. 2 Proceedings of SPIE 6104 M. Traub, H.-D. Hoffmann, Seiten 212-213, 2006 Seiten 61040O.1-61040O.8, 2006 H.-D. Plum, K. Wieching, P. Loosen, R. Poprawe D. Petring R. Liebers, U. Dürr, L. Trippe, Homogenization of high power Laserschneiden und -schweissen W. Schulz diode laser beams for pumping im fliegenden Wechsel Drilling Strategies for Metals and direct applications Technische Rundschau 16 with Pulsed YAG-Lasers Proceedings of SPIE 6104 Seiten 38-41, 2006 Proceedings of ICALEO 25 Seiten 61040Q.1-61040Q.10, 2006 6 Seiten, 2006 D. Petring R. Noll, V. Sturm, M. Stepputat, Lasers in European Automotive A. Whitehouse, J. Young, P. Evans Manufacturing: Historical Industrial applications of LIBS Review and Recent Trends Laser-Induced Breakdown Spec- Proceedings of ALAW 2006 troscopy (LIBS): Fundamentals and 16 Seiten, 2006 Applications Seiten 400-439, 2006

Fraunhofer ILT Annual Report 2006 135 Scientific Publications

A. Gillner, K. Klages, F. Sarı V. Sturm, A. Brysch, R. Noll, I. Kelbassa, C. Over, L. Trippe, Mikrofügen mit Laserstrahlung H. Brinkmann, R. Schwalbe, E. W. Kreutz, K. Wissenbach Laser Technik Journal 3 K. Mülheims, P. Luoto, P. Mannila, Reconditioning of Nickel Base Seiten 39-43, 2006 K. Heinänen, D. Carrascal, L. Sancho, HPT Blades and Vanes used in A. Opfermann, K. Mavrommatis, Aero Engines and Power Plant K. Nicklaus, M. Hoefer, D. Hoffmann, H. W. Gudenau, A. Hatziapostolou, Gas Turbines by Combination J. Luttmann, R. Wester, R. Poprawe S. Couris of Direct Laser Forming, Laser MOPA with kW average power Online multi-element analysis Metal Deposition and Laser and multi MW peak power: of the top gas of a blast furnace Drilling experimental results, theoretical by LIBS Proceedings of PICALO modeling and scaling limits 7th International Workshop 7 Seiten, 2006 Proceedings of SPIE 6100 Progress in Analytical Chemistry Seiten 610416.1-610416.11, 2006 in the Steel and Metal Industries, B. Regaard, S. Kaierle, R. Poprawe Ed. J. Angeli Self guided laser welding J. Ilgner, M. Wehner, J. Lorenzen, Seiten 183-188, 2006 Proceedings of ICALEO 25 M. Bovi, M. Westhofen 7 Seiten , 2006 Morphological effects of nano- K. Nicklaus, M. Daniels, R. Hohn, second- and femtosecond-pulsed D. Hoffmann R. Noll, C. Fricke-Begemann laser ablation on human middle Optical Isolator for Unpolarized Stand-off Detection of Surface ear ossicles Laser Radiation at Multi-Kilo- Contaminations with Explosive Journal of Biomedical Optics 11 watt Average Power Residues Using Laser-spectros- Seiten 41-47, 2006 OSA - Technical Digest copic Methods »Advanced Solid-State Photonics« Stand-off Detection of Suicide H. Balzer, M. Höhne, R. Noll, V. Sturm 3 Seiten, 2006 Bombers and Mobile Subjects, New approach for online moni- Eds.: H. Schubert, A. Rimski-Korsakov toring of the Al depth profile I. Kelbassa, K. Walther, L. Trippe, Seiten 89-99, 2006 of the hot-dip galvanised sheet W. Meiners, C. Over steel using LIBS Potentials of manufacture R. Wagner, J. Gottmann, A. Horn, Analytical & Bioanalytical Chemistry and repair of nickel base E. W. Kreutz Vol. 385, No. 2 turbine components used in Subwavelength ripple formation Seiten 225-233, 2006 aero engines and power plants induced by tightly focused by laser metal deposition and femto-second laser radiation T. Ebert, W. Meiners, M. Pajunk laser drilling Applied Surface Science Vol. 252, Non corrosive micro coolers Proceedings of ISJPPE 2025 Issue 24 with matched CTE 9 Seiten, 2006 Seiten 8576-8579, 2006 Proceedings of SPIE 6104 Seiten 01.1-01.7, 2006 J. Vrenegor, V. Sturm, R. Noll, H. Balzer, S. Hölters, V. Sturm, M. Hemmerlin, U. Thurmann, J. Flock R. Noll H. Balzer, M. Hoehne, S. Hoelters, Preparation and analysis Systematic line selection V. Sturm, R. Noll, E. Leunis, of production control samples for online coating thickness S. Janssen, M. Raulf, P. Sanchez, by a two-step laser method measurement of galvanised M. Hemmerlin 7th International Workshop sheet steel using LIBS Analytical Online depth profiling of zinc Progress in Analytical Chemistry & Bioanalytical Chemistry coated sheet steel by laser induced in the Steel and Metal Industries, Vol. 385, No. 2 breakdown spectroscopy Ed. J. Angeli Seiten 234-239, 2006 7th International Workshop Seiten 81-86, 2006 Progress in Analytical Chemistry R. Noll in the Steel and Metal Industries, L. Trippe, K. Walther, E.W. Kreutz, Terms and notations for laser- Ed. J. Angeli R. Poprawe induced breakdown spectroscopy Seiten 237-242, 2006 Process development and control Analytical & Bioanalytical Chemistry of laser drilled and shaped holes Vol. 385, No. 2 in turbine components Seiten 214-218, 2006 Proceedings of LAMP 5 Seiten, 2006 J. Ilgner, M. Wehner, A. Donner, P. Düwel, R. Poprawe, M. Westhofen R. Poprawe, E. W. Kreutz, L. Trippe, 200 µm glass fibres for minimally K. Walther invasive laser procedures in Process development for laser paranasal sinus surgery drilled hole arrays in cooled Medical Laser Application 21 structures Seiten 45-51, 2006 Tagungsband zum 3. Workshop des SFB 561 Seiten 34-38, 2006

136 Fraunhofer ILT Annual Report 2006 Lectures

12.01.2006 - W. Neff 24.01.2006 - M. Traub 24.02.2006 - R. Poprawe 14.03.2006 - H.-D. Hoffmann Laserinduzierte Mikroplasmen Homogenization of high power Creation of the European Festkörperlaser und Diodenlaser Fachgespräch »Mikroplasmen« diode lasers for pumping and Technology Platform für das Schweißen von Kunst- Begegnungszentrum Hof Beck- direct applications »Photonics 21«, National Laser stoffen mann, Ruhr-Universität Bochum, Photonics West 2006, San Jose, Center, Pretoria, Südafrika Laserschweißen von Kunststoffen, Bochum CA, USA Süddeutsches Kunststoffzentrum - 27.02.2006 - K. Walther Kunststoff, Forschung und Entwick- 22.01.2006 - M. Roehner 25.01.2006 - M. Hoefer Laser technologies for manu- lung, SKZ-KFE GmbH, Würzburg Characterization device for High power second and third facturing and repair of rotating measuring beam parameter harmonics generation of a two machinery power plant compo- 15.03.2006 - E. W. Kreutz product and beam quality stage partially diode end-pumped nents Lasersicherheit - was ist wirklich of collimated and uncollimated Nd:YAG INNOSLAB MOPA System ISROMAC-11, Honolulu, Hawaii, wichtig? diode lasers Photonics West 2006, San Jose, USA Süddeutsches Kunststoffzentrum, Photonics West 2006, San Jose, CA, USA Würzburg CA, USA 06.03.2006 - H. Balzer 25.01.2006 - K. Nicklaus Online-Tiefenprofilanalyse 15.03.2006 - K. Walther 23.01.2006 - R. Noll Mopa with kW average power verzinkter Stahlbleche mit Laser- Process development for laser Laser-Emissionsspektroskopie - and multi MW peak power: Emissionsspektrometrie (LIBS) drilled hole arrays in cooled Grundlagen, Grenzen und indus- experimental results theoretical 13. Anwendertreffen Röntgenflu- structures trielle Anwendungspotentiale modelling and scaling limits orezenz und Funkenemissionspek- Workshop SFB561, Aachen Kolloquium, Fraunhofer-Institut für Photonics West 2006, San Jose, trometrie, Steinfurt Zerstörungsfreie Prüfverfahren IZFP, CA, USA 27.03.2006 - U. Eppelt Saarbrücken 06.03.2006 - G. Otto Microprocessing, from nano 25.01.2006 - J. Wüppen Lasereinsatz in der Verpackungs- to femto 23.01.2006 - M. Leers High efficient generation of technik 14th Annual Automotive Laser Expansion-matched passively- tunable visible light by means Workshop »Easy Opening«, Fraun- Applications Workshop ALAW cooled heatsinks with low ther- of DFG in self-controlled con- hofer-Institut für Verfahrenstechnik 2006, Plymouth, MI, USA mal resistance for high-power version processes u. Verpackung IVV, Freising diode laser bars Photonics West 2006, San Jose, 27.03.2006 - C. A. Hartmann Photonics West 2006, San Jose, CA, USA 06.03.2006 - E. W. Kreutz Untersuchung zum Abtrag von CA, USA Biologische Grundlagen Metallen mit Pikosekunden und 26.01.2006 - J. Gottmann und zulässige Grenzwerte zur Nanosekunden Mehrfachpulsen 23.01.2006 - C. Scholz Sub-wavelength ripple forma- Klassifizierung DPG-Frühjahrstagung, Universität Comparison between 50 W tion on dielectric and metallic Hochschulübergreifende Fortbildung, Augsburg, Institut für Physik, tapered laser arrays and tapered materials induced by tightly Universität Siegen Augsburg single emitters focused femto-second laser Photonics West 2006, San Jose, radiation 08.03.2006 - M. Dahmen 27.03.2006 - A. Horn CA, USA Photonics West 2006, San Jose, Laser materials processing - appli- Ausgewählte Anwendungen CA, USA cations, methods and systems der Wechselwirkung von 24.01.2006 - B. Jungbluth National Laser Centre, Tshwane Femtosekunden Laserstrahlung High performance, widely 26.01.2006 - K. Wissenbach (Pretoria), Südafrika mit Materie tunable Ti:Sapphire laser, with Lasereinsatz in der Oberflächen- DPG-Frühjahrstagung, Universität nanosecond pulses behandlung 09.03.2006 - G. Otto Augsburg, Institut für Physik, Photonics West 2006, San Jose, MPA Darmstadt, Darmstadt Laserverfahren für die Ver- Augsburg CA, USA packung medizintechnischer 30.01.2006 - K. Nicklaus Produkte 27.03.2006 - I. Mingareev 24.01.2006 - P. Russbüldt Optical isolator for unpolarized 3. Duisburger Extrusionstagung, Prozessvisualisierung bei der Generation of 13.5-fs pulses laser radiation at multi-kilowatt Universität Duisburg Gesamthoch- Materialbearbeitung mit ultra- from a diode-pumped Kerr-lens average power schule, Duisburg kurzen Laserpulsen mittels mode-locked prismless Cr:LiSGaF ASSP 2006, Lake Tahoe, Nevada, Pump&Probe-Photographie laser USA 11.03.2006 - R. Noll DPG-Frühjahrstagung, Universität Photonics West 2006, San Jose, New frontiers for Laser-Induced Augsburg, Institut für Physik, CA, USA 31.01.2006 - J. Loehring Breakdown Spectroscopy Augsburg Thermal effects on the scalability Pittcon 2006, 57th Pittsburgh 24.01.2006 - C. Wessling of high power third harmonic Conference on Analytical Chemistry 28.03.2006 - A. Gillner Dense wavelength multiplexing generation at 355 nm in LBO and Applied Spectroscopy, Großflächenabtrag mit for a high power diode laser ASSP 2006, Lake Tahoe, Nevada, Invited Talk auf Symposium LIBS Kurzpulslaserstrahlquellen Photonics West 2006, San Jose, USA 21st Century, Orlando, FL, USA DPG-Frühjahrstagung, Universität CA, USA Augsburg, Institut für Physik, 08.02.2006 - T. Mans 11.03.2006 - E. W. Kreutz Augsburg Optronik Praktische Schutzmaßnahmen Bundesagentur für Außenwirtschaft bei der Laseranwendung BFAI, Köln Haus der Technik, Essen

Fraunhofer ILT Annual Report 2006 137 Lectures

28.03.2006 - D. Petring 12.04.2006 - A. L. Boglea 09.05.2006 - R. Poprawe 17.05.2006 - A. Horn Combined cutting and welding Innovative laser based pick- Neue Trends in der Lasertechnik Diagnostics of laser-induced Fraunhofer Pre-Conference of and-join tool for micro-assembly - Chancen und Märkte für Inves- melting of matter by ultra-fast ALAW 2006, Plymouth, MI, USA Marie Curie Conference MC2, toren metrology »Putting the Knowledge-based Investmentforum, München LAMP 2006, Kyoto Research Park, 28.03.2006 - R. Poprawe Society into Practice«, University of Kyoto, Japan New lasers for new applications Manchester, Manchester, UK 15.05.2006 - K. Wissenbach Fraunhofer Pre-Conference of Potentials of highly-developed 17.05.2006 - C. A. Hartmann ALAW 2006, Plymouth, MI, USA 24.04.2006 - E. Bremus-Köberling laser base techniques for additive Investigation on laser micro Neuron-material interactions manufacturing and repair of ablation of steel using short 29.03.2006 - E. W. Kreutz on surfaces with complex topo- complex shaped aero engine and ultrashort IR multipulses Process development and graphies (Poster) parts out of nickel and titanium LAMP 2006, Kyoto Research Park, control of melt dominated laser 2006 Regenerate - World Congress base alloys Kyoto, Japan drilling on Tissue Engineering and Regene- ASM Konferenz, Seattle, WA, USA DPG-Frühjahrstagung, Universität rative Medicine, Pittsburgh, PA, USA 17.05.2006 - J. Gottmann Augsburg, Institut für Physik, 16.05.2006 - E. W. Kreutz Investigation of ripples with sub- Augsburg 03.05.2006 - S. Kaierle Lasersicherheit wavelength periodicity induced Wie funktionieren die BG Feinmechanik & Elektrotechnik, by tightly focused femtosecond 30.03.2006 - D. Petring Laserbearbeitungsverfahren? Bad Münstereifel laser radiation on various mate- Lasers in European automotive Aachener Kolloquium für Laser- rials manufacturing: Historical review technik AKL’06, Aachen 16.05.2006 - R. Wester LAMP 2006, Kyoto Research Park, and recent trends Fast characterisation of steel Kyoto, Japan 14th Annual Automotive Laser 04.05.2006 - A. Gillner cleanness by advanced mathe- Applications Workshop ALAW Kombilas - Laserpräzisionsabtrag matical analysis of spark and 18.05.2006 - D. Wortmann 2006, Plymouth, MI, USA von Keramikwerkstoffen laser source optical emission data Refractive index modification in Aachener Kolloquium für Laser- CETAS2006, 7th International fused silica with fs-double-pulses 30.03.2006 - M. Ramme technik AKL’06, Aachen Workshop on Progress in Analytical LAMP 2006, Kyoto Research Park, Doppelpulse Chemistry in the Steel and Metal Kyoto, Japan DPG-Frühjahrstagung, Universität 04.05.2006 - R. Poprawe Industries, Luxemburg, Luxemburg Augsburg, Institut für Physik, Trends und Perspektiven der 19.05.2006 - R. Poprawe Augsburg Lasertechnik 16.05.2006 - Ü. Aydin Perspectives of laser processing Aachener Kolloquium für Laser- Automatic sorting of aluminium and new applications 03.04.2006 - R. Poprawe technik AKL’06, Aachen alloys by fast LIBS identification LAMP 2006, Kyoto Research Park, Holistic development of CETAS 2006, 7th International Kyoto, Japan high power laser sources and 04.05.2006 - W. Meiners Workshop on Progress in Analytical corresponding applications Schnelle Herstellung von Chemistry in the Steel and Metal 28.05.2006 - C. Johnigk PICALO 2006, Melbourne, Bauteilen mit Mikrostrukturen Industries, Luxemburg, Luxemburg Reinigen und Vorbehandeln Australien mit dem SLM-Verfahren mit Laserstrahlung Aachener Kolloquium für Laser- 16.05.2006 - H. Balzer OTTI-Profiforum »Reinigen und Vor- 05.04.2006 - I. Kelbassa technik AKL'06, Aachen Online depth profiling of zinc behandeln vor der Beschichtung«, Comparison of Ti-6246 BLISK coated sheet steel by Laser-In- OTTI Kolleg e.V., Regensburg blade repair methods on blade 05.05.2006 - D. Petring duced Breakdown Spectroscopy replacement via repair by laser Flexibles Laserschneiden und CETAS 2006, 7th International 28.05.2006 - A. L. Boglea welding and reconditioning -schweißen von Blechbaugruppen Workshop on Progress in Analytical Advanced laser based tools for of local damages by laser depo- ohne Werkzeugwechsel Chemistry in the Steel and Metal micro-assembly sition Aachener Kolloquium für Laser- Industries, Luxemburg, Luxemburg Poduktionstechnik Seminar, Tech- PICALO 2006, Melbourne, technik AKL’06, Aachen nical University Cluj-Napoca, Faculty Australien 16.05.2006 - V. Sturm of machine, Cluj-Napoca, Rumänien 05.05.2006 - R. Noll Online multi-element analysis 05.04.2006 - I. Kelbassa Laser-Direktanalyse von Prozess- of the top gas of a blast furnace 31.05.2006 - K. Wissenbach Reconditioning of Nickel base kontroll- und Schlackeproben by LIBS Lasereinsatz in der Oberflächen- HPT blades and vanes used in in der Sekundärmetallurgie CETAS 2006, 7th International technik - Ein Überblick aero engines and power plant Ausschusssitzung »Metallurgische Workshop on Progress in Analytical Aachener Laserseminar »Vorsprung gas turbines by combination of Grundlagen«, Stahlinstitut VDEh, Chemistry in the Steel and Metal durch Laser-Oberflächentechnik - direct laser forming, laser metal Düsseldorf Industries, Luxemburg, Luxemburg Auftragschweißen, Reparieren, Reini- deposition and laser drilling gen, Polieren«, Fraunhofer-Institut PICALO 2006, Melbourne, 07.05.2006 - I. Mingareev 16.05.2006 - J. Vrenegor für Lasertechnik ILT, Aachen Australien Extension of the process limits Preparation and analysis in material processing with of production control samples 31.05.2006 - C. Jonhnigk 05.04.2006 - I. Kelbassa femtosecond laser radiation by a two-step laser method Reinigen mit Laserstrahlung Laser metal deposition by means of high-speed pump- CETAS 2006, 7th International Aachener Laserseminar »Vorsprung of TiAl alloys probe photography Workshop on Progress in Analytical durch Laser-Oberflächentechnik - PICALO 2006, Melbourne, SPIE High Power Laser Ablation Chemistry in the Steel and Metal Auftragschweißen, Reparieren, Reini- Australien 2006, Sagebrush Inn & Conference Industries, Luxemburg, Luxemburg gen, Polieren«, Fraunhofer-Institut Center, Taos, NM, USA für Lasertechnik ILT, Aachen

138 Fraunhofer ILT Annual Report 2006 Lectures

31.05.2006 - E. Willenborg 16.06.2006 - S. Abed 28.06.2006 - Ü. Aydin 03.09.2006 - R. Poprawe Polieren mit Laserstrahlung Manufacture of injection moulds High speed identification of The future of high power laser Aachener Laserseminar »Vorsprung out of standard tool steel using aluminium alloys by Laser-Induced techniques durch Laser-Oberflächentechnik - direct laser forming Breakdown Spectroscopy for XVI. International Symposium Auftragschweißen, Reparieren, Reini- 10th International Pattern Model material recycling GCL/HPL 2006, Gmunden, Österreich gen, Polieren«, Fraunhofer-Institut Making Congress, Maison de la LZH Laser Zentrum Hannover e.V., für Lasertechnik ILT, Aachen Mécanique, UFIMO (Union Française Hannover 03.09.2006 - R. Noll des Industries de Mise en Forme Applications of LIBS 31.05.2006 - K. Wissenbach des Métaux et Outillage), Paris, 28.06.2006 - C. D. Gehlen LIBS 2006, 4th International Confe- Strukturieren mit Laserstrahlung Frankreich Ortsaufgelöste Untersuchung rence on Laser-Induced Breakdown Aachener Laserseminar »Vorsprung laserinduzierter Plasmen beim Spectroscopy and Applications, durch Laser-Oberflächentechnik - 21.06.2006 - M. Wehner präzisen Mikro-Materialabtrag Montreal, Kanada Auftragschweißen, Reparieren, Reini- Single cell optoporation mit Pulsgruppen gen, Polieren«, Fraunhofer-Institut for uptake of extracellular LZH Laser Zentrum Hannover e.V., 05.09.2006 - R. Noll für Lasertechnik ILT, Aachen substances (Poster) Hannover TeleLis - Remote LIBS measure- Jahrestagung »Mikrosysteme für ments with double pulses 31.05.2006 - G. Vitr die Biotechnologie«, Fraunhofer- 04.07.2006 - E. W. Kreutz LIBS 2006, 4th International Confe- Randschichthärten und Institut für Fertigungstechnik und Laser in der Materialbearbeitung rence on Laser-Induced Breakdown Wärmebehandeln von Stählen angewandte Materialforschung und andere als optische und Spectroscopy and Applications, mit Laserstrahlung IFAM, Bremen elektrische Gefahren Montreal, Kanada Aachener Laserseminar »Vorsprung TA Esslingen, Ostfildern durch Laser-Oberflächentechnik - 21.06.2006 - M. Wehner 05.09.2006 - R. Noll Auftragschweißen, Reparieren, Reini- Rapid prototyping of microfluidic 06.07.2006 - E. W. Kreutz High-speed LIBS with low energy gen, Polieren«, Fraunhofer-Institut devices in polymers (Poster) Gefährdungen von Augen und multiple pulses for online moni- für Lasertechnik ILT, Aachen Jahrestagung »Mikrosysteme für Haut durch Laserstrahlung toring of thickness and depth die Biotechnologie«, Fraunhofer- BG Metall-Süd, profile of galvanised sheet steel 31.05.2006 - A. Weisheit Institut für Fertigungstechnik und Markt Triefenstein-Lengfurt LIBS 2006, 4th International Confe- Laserstrahl-Auftragschweißen angewandte Materialforschung rence on Laser-Induced Breakdown von Funktionsschichten für den IFAM, Bremen 06.07.2006 - M. Leers Spectroscopy and Applications, Verschleiß- und Korrosionsschutz Stress reduced packaging Montreal, Kanada Aachener Laserseminar »Vorsprung 22.06.2006 - G. Backes Bright-EU Workshop, University durch Laser-Oberflächentechnik - Laserbearbeitung bei Triebwerken of Cambridge, Cambridge, UK 06.09.2006 - R. Noll Auftragschweißen, Reparieren, Reini- Bundesakademie für Wehrverwal- Standardization of LIBS gen, Polieren«, Fraunhofer-Institut tung und Wehrtechnik, Mannheim 06.07.2006 - D. Petring LIBS 2006, 4th International Confe- für Lasertechnik ILT, Aachen Kombiniertes Schneiden und rence on Laser-Induced Breakdown 22.06.2006 - S. Abed Schweißen: Laserstrahlqualität Spectroscopy and Applications, 31.05.2006 - A. Gasser Fabrication directe d’outillages steigert Prozesseffizienz und Montreal, Kanada Anlagen-Systemtechnik für die d’injection en aciers outil stan- -flexibilität Laseroberflächentechnik dard et de pièces techniques 2. Internationaler Workshop 13.09.2006 - W. Wawers Aachener Laserseminar »Vorsprung en alliages d’Aluminium et de Faserlaser, Dresden Laser drilling with helical drilling durch Laser-Oberflächentechnik - Titane par fusion laser de poudre optics Auftragschweißen, Reparieren, Reini- Journée technique, Université de 13.07.2006 - R. Poprawe 1. Internationales Symposium gen, Polieren«, Fraunhofer-Institut Technologie de Belfort-Montbéliard, Lasertechnik: Wie aus Technik für das Laser-Micromachining, für Lasertechnik ILT, Aachen Site de Sevenan, Belfort, Frankreich Unternehmen werden Chemnitz Business Angels Veranstaltung, 06.06.2006 - T. Mans 27.06.2006 - H.-D. Hoffmann Aachen 13.09.2006 - A. Gillner Optische Technologien - Zukunft High-power solid-state slab- Laserstrahlmikroschweißen mit und Technik lasers and nonlinear frequency 17.07.2006 - S. Kaierle Faserlasern und innovativen Ver- Konferenz Zukunft und Technik, conversion Laser aided manufacturing fahrenskonzepten Dormagen Laser Optic Conference, A. F. Ioffe in Germany and Europe Laser-Anwender-Forum, BIAS, Physical-Technical Institute, GARELAM, National Academy Bremen 13.06.2006 - R. Noll St. Petersburg, Russland of Science, Washington, USA Online depth profiling of zinc 20.09.2006 - A. Gasser coated sheet steel by Laser-Indu- 28.06.2006 - F. Schmitt 18.07.2006 - E. W. Kreutz Aplicaciones industriales de la ced Breakdown Spectroscopy Vergleich des Perkussions- Einrichten von Laserbereichen soldadura de aporte con láser TGS9, ECSC Meeting, Rotherham, und Wendelbohrens mit Kurz- und andere als optische Gefahren- Jornada de Difusion Technológica, UK pulslasern potenziale Lortek, Ordizia, Spanien WLT-Summerschool, LZH Laser BG Metall-Süd, 16.06.2006 - W. Meiners Akademie, Hannover Markt Triefenstein-Lengfurt 24.09.2006 - S. Kaierle Manufacturing of individual Laser materials processing: appli- bone implants using selective cations, methods and systems laser melting Fachmesse INSITE, Johannesburg, 2. Bernd-Spiessl-Symposium 2006, Südafrika Basel, Schweiz

Fraunhofer ILT Annual Report 2006 139 Lectures

25.09.2006 - N. Pirch 18.10.2006 - S. Kaierle 07.11.2006 - C. Wessling 21.11.2006 - S. Kaierle Mechanisms of surface rippling Qualitätssicherung in der Fasergekoppelte Diodenlaser- Nahtfolge und Nahtinspektion - during laser polishing Laserbearbeitung durch optische systeme hoher Brillanz Grundlagen und Anwendungs- 8th International Seminar »Nu- Schweißnahtüberwachung IWS Workshop Diodenlaser, beispiele merical Analysis of Weldability«, Fachtagung Optische Industrie- Fraunhofer-Institut für Werkstoff- Aachener Laserseminar »Online Graz-Seggau, Östereich sensorik, Böblingen und Strahltechnik IWS, Dresden Qualitätssicherung in der Laserfüge- technik - Sicheres und effizientes 27.09.2006 - N. Pirch 20.10.2006 - S. Kaierle 08.11.2006 - R. Noll Laserstrahlschweißen«, Calculations of stresses during Qualitätssicherung beim Löten Industrielle Anwendungen der Fraunhofer ILT, Aachen laser welding, shortcomings mit Laserstrahlung Laser-Direktanalyse of finite element approximation GFaI Jahresversammlung, Gesell- Jahrestagung GDMB, Goslar 21.11.2006 - B. Regaard 8th International Seminar »Nu- schaft zur Förderung angewandter Autonome Nahtfolge merical Analysis of Weldability«, Informatik e.V. (GFaI), Berlin 09.11.2006 - S. Kaierle Aachener Laserseminar »Online Graz-Seggau, Östereich Industrielle Anwendungen Qualitätssicherung in der Laserfüge- 27.10.2006 - A. Gillner brillianter Diodenlaser beim technik - Sicheres und effizientes 04.10.2006 - J. Holtkamp Lasergestütztes Gewebekleben Aluminiumschweißen, Härten Laserstrahlschweißen«, Laser assisted forming: für Anastomosen und zum naht- und Beschichten Fraunhofer ILT, Aachen process & tools freien Wundverschluss IWS Workshop Diodenlaser, Masmicro Demonstration Day, LIME Erlangen, BLZ – Bayerisches Fraunhofer-Institut für Werkstoff- 22.11.2006 - D. Petring Stuttgart Laserzentrum GmbH, Erlangen und Strahltechnik IWS, Dresden Laserstrahlschneiden und -schweißen: Grundlagen für die 11.10.2006 - P. Abels 31.10.2006 - A. L. Boglea 16.11.2006 - D. Petring Anwendung Quality control in laser materials Fiber laser pick-and-join tool Flexibles Schneiden und Aachener Laserseminar »Innovative processing - essentials and indu- for welding of thermoplastics Schweißen in der Blechverarbei- Laserschneid- und Laserschweiß- strial application ICALEO® 2006, Scottsdale, tung mit dem Laser-Kombikopf prozesse«, Fraunhofer ILT, Aachen ILAS Konferencia 2006, Bay Zoltán Arizona, USA Fertigungstechnisches Kolloquium Institute for Materials Science and der ETH Zürich, IWF Institut für 22.11.2006 - D. Petring Technology, Budapest, Ungarn 31.10.2006 - B. Regaard Werkzeugmaschinen und Fertigung, Laserhybridschweißen: Stand der Self guided laser welding Zürich, Schweiz Technik und aktuelle Fortschritte 11.10.2006 - E. Bremus-Köberling ICALEO® 2006, Scottsdale, Aachener Laserseminar »Innovative Neurite growth on micro- Arizona, USA 20.11.2006 - S. Kaierle Laserschneid- und Laserschweiß- patterned surfaces with complex Prozessüberwachung für die prozesse«, Fraunhofer ILT, Aachen topographies (Poster) 01.11.2006 - A. Olowinsky Materialbearbeitung mit Laser- 2006 Annual Fall Meeting, Biome- SHADOW® - new applications strahlung - Grundlagen und 22.11.2006 - F. Schneider dical Engineering Society (BMES), in electronics and micromecanics Anwendungsgebiete Flexible Fertigung von Blechbau- Chicago, IL, USA ICALEO® 2006, Scottsdale, Aachener Laserseminar »Online gruppen: effizient Laserstrahl- Arizona, USA Qualitätssicherung in der Laserfüge- schweißen und -schneiden mit 15.10.2006 - K. Bergmann technik - Sicheres und effizientes dem Kombikopf Characterization of grazing 01.11.2006 - J. Gedicke Laserstrahlschweißen«, Aachener Laserseminar »Innovative incidence collectors under near Comparison of different process Fraunhofer ILT, Aachen Laserschneid- und Laserschweiß- production conditions (Poster) monitoring methods for laser prozesse«, Fraunhofer ILT, Aachen EUVL Symposium 2006, International beam micro welding 20.11.2006 - S. Mann Symposium on Extreme Ultraviolet ICALEO® 2006, Scottsdale, Prozessüberwachung mit 22.11.2006 - G. Otto Lithography, Barcelona, Spanien Arizona, USA koaxialer Fremdbeleuchtung Prozesslösungen zum Laser- Aachener Laserseminar »Online trennen von Leiterplatten mit 15.10.2006 - L. Juschkin 02.11.2006 - E. Willenborg Qualitätssicherung in der Laserfüge- Materialstärke >1 mm EUV microscopy for defect Automatisches Polieren technik - Sicheres und effizientes Laser-Workshop, Gas Automation inspection (Poster) von Umformwerkzeugen der Laserstrahlschweißen«, GmbH, St. Georgen (Schwarzwald) EUVL Symposium 2006, International Kaltmassivumformung Fraunhofer ILT, Aachen Symposium on Extreme Ultraviolet Workshop Polieren mit dem Laser, 23.11.2006 - R. Noll Lithography, Barcelona, Spanien GCFG, Hagen 20.11.2006 - A. Gillner Grundlagen und Methoden Micro and nanofunctionalization der Lasermesstechnik - Stand der 16.10.2006 - K. Bergmann 07.11.2006 - M. Traub of surfaces Technik und neue Entwicklungen Test stand for optical characte- Prozessangepasste Formung Nanofair Karlsruhe, Kongresszentrum Aachener Laserseminar »Lasermess- rization of grazing incidence und Homogenisierung von Karlsruhe, Karlsruhe technik für die metallverarbeitende collectors (Poster) Diodenlaserstrahlung Industrie«, Fraunhofer ILT, Aachen EUVL Symposium 2006, International IWS Workshop Diodenlaser, Symposium on Extreme Ultraviolet Fraunhofer-Institut für Werkstoff- Lithography, Barcelona, Spanien und Strahltechnik IWS, Dresden

140 Fraunhofer ILT Annual Report 2006 Lectures Conventions and Conferences

23.11.2006 - A. Lamott 12.01.2006 Online-Überwachung von Chair for Laser Technology LLT Schweißprozessen mit Emissions- at RWTH Aachen spektrometrie Lecture in association with the Aachener Laserseminar »Lasermess- RWTH Colloquium on Laser technik für die metallverarbeitende Technology Industrie«, Fraunhofer ILT, Aachen Prof. Wolfgang Kowalsky, Technische Universität Braunschweig, Institut 27.11.2006 - J. Wilkes für Hochfrequenztechnik Rapid manufacturing of ceramic »Organische Leuchtdioden und components for medical and Laser« technical applications via selec- tive laser melting 21.02.2006, Aachen Euro-uRapid, Frankfurt am Main Unihits for Kids Forum organized by the Chair 30.11.2006 - W. Meiners for Laser Technology LLT and the Vorsprung im Werkzeugbau Fraunhofer ILT to give advice on durch innovative Lasertechnik scientific careers to students at the Euromold 2006, Fachforum Gesamtschule Langerwehe. Werkzeug und Formenbau, Frankfurt am Main 03.03.2006, Aachen 22nd seminar of the »Aix Laser 05.12.2006 - E. W. Kreutz People« Technische, organisatorische und the alumni club of the Fraunhofer persönliche Schutzmaßnahmen ILT and the Chair for Laser Techno- bei der Materialbearbeitung mit logy LLT, featuring lectures by Laserstrahlung Dr. Stefan Kaierle, Fraunhofer ILT, BG Feinmechanik & Elektrotechnik, on »New developments in systems Dresden engineering at the Fraunhofer ILT« and Dr. Detlef Becker, Vorwerk 06.12.2006 - R. Poprawe Elektrowerke GmbH, Wuppertal, on Photonics21 - Die neue the topic of »Quality management Above: Opening of the schools event »The Fascination of Light« EU Technologieplattform in the procurement of engineering on May 2, 2006, at the Ludwig Wissenschaftliches Forum, Ulm products«. The lectures were followed Forum for International Art in by a visit to the premises of FEV Aachen. Middle: Federal minister 08.12.2006 - R. Noll Motorentechnik GmbH in Aachen. Dr. Annette Schavan at the Physik - Aufgabe und Beruf science forum in Ulm. Pius Gymnasium, Aachen Below: Presentation of certificate to the Fraunhofer ILT on May 2, 2006, in Aachen, confirming its 08.12.2006 - S. Pfeiffer selection as a »landmark« in the Strukturelle Stabilität von »Land of Ideas«. Modellen zur Schweißverzugs- simulation von Stahlwerkstoffen FOSTA-Arbeitskreis Schweißverzug, zwb München

12.12.2006 - K. Wissenbach Laser surface treatment Short course on »Material Processing by Laser«, AIDO, Paterna, Spanien

13.12.2006 - S. Abed Fabrication rapide de pièces métalliques et d‘outillages par fusion laser 5eme Journée Technique Fabrication Rapide: réalité ou utopie? Tendance du marché et enjeux futurs Pôle Européen de Plasturgie, Oyonnax, Frankreich

Fraunhofer ILT Annual Report 2006 141 Conventions and Conferences

28.03.2006 Colloquium for Laser Technology Köhler (see also www.land-der- Plymouth, Michigan, USA AKL´06 (www.ilt.fraunhofer.de/akl06) ideen.de). The Fraunhofer ILT was »Open house CLT« enabled tomorrow’s university stu- one of the 365 successful appli- The Fraunhofer CLT held an open dents to get to know this expand- cants out of a total of 1200 to be day on March 28, 2006, as part of ing sector of industry. Expertly selected as a »landmark« in the the Automotive Laser Applications prepared learning activities and Land of Ideas. The certificate awar- Workshop ALAW. Over 100 visitors presentations fired the youngsters’ ded in connection with this honor attended presentations on Fraunho- enthusiasm. Careers advisors were was officially presented to the fer laser activities in Germany and on hand to provide details of the Fraunhofer ILT on May 2 during the USA. Lectures were given on job opportunities available in this a press conference at the Ludwig laser materials processing on the sector of industry. Forum in Aachen. micro and macro scales, and on the latest developments in components To conduct this schools event, the 03. - 05.05.2006, Aachen and laser resonators. The results of Fraunhofer ILT arranged for the 6th Aachen Colloquium for various research projects were pre- BMBF-sponsored travelling exhibition Laser Technology AKL’06 sented: laser welding with high- »The Fascination of Light« to be The Aachen Colloquium for Laser power fiber lasers, integrated laser installed at the Ludwig Forum Technology AKL is the industry’s key cutting and welding with the combi for International Art. An area of forum for applied laser technology. head, robot-assisted remote weld- approx. 250 m2 was filled with This year about 430 participants, ing, micromaterials processing in hands-on exhibits and accompany- including representatives of nume- connection with drilling and joining, ing explanatory material. Research rous laser manufacturers and users and surface processing techniques staff from the Fraunhofer ILT and of laser technology, gathered in such as coating and cleaning. The students from the Chair for Laser Aachen to discuss success stories, components and systems demons- Technology LLT at RWTH Aachen potential applications and recent trated to visitors ranged from scan- University looked after the visiting developments in the field of laser ners for 10-kW fiber lasers with school groups at the Ludwig Forum technology. Using examples from autonomous position recording, during the four days of the event. practical industrial applications and fiber lasers with flexible pulse para- The students were also introduced innovative R&D projects, a total of meters and extremely high-brilliance to the significance of light as an 32 technical lectures illustrated the diode lasers (75 W output from a artistic medium. For this part of prospects of laser technology for a 100-µm fiber) to complete customer- their visit, the students were guided wide variety of applications in such specific systems for manufacturing by the specialist teachers of the diverse industries as automobile use. Ludwig Forum’s permanent muse- manufacturing, metal processing, um staff. tool and die making, optical, elec- 20.04.2006 trical and electronic engineering. Chair for Laser Technology LLT The Fraunhofer ILT’s schools event Non-financial sponsors of the con- at RWTH Aachen at the Ludwig Forum was also ference included the Association of Lecture in association with incorporated in a one-day event German Engineers (VDI), the Ger- the RWTH Colloquium on Laser devoted to optical technologies man Association of Automobile Technology held on May 2 in Aachen as part of Manufacturers (VDA), the German Dr. Martin Straub, Lehrstuhl für the initiative »Zukunft durch Inno- Engineering Federation (VDMA) Lasertechnik, RWTH Aachen vation.NRW« organized by the and the German Association of Above: School students discovering »The Fascination of Light« on May 2, »Femtosecond-fabrication and ana- Land of North Rhine-Westphalia. Optical, Medical and Mechatronics 2006, at the Ludwig Forum for Inter- lysis of micro- and nanostructures« This event was supported by small Manufacturers (SPECTARIS). national Art in Aachen. and medium-sized enterprises Middle and below: School students taking part in the initiative »Zukunft 26.04.2006 (SMEs) in addition to the participat- In addition to lectures held by laser durch Innovation«. Chair for Laser Technology LLT ing universities and research insti- experts from industrial companies at RWTH Aachen tutions. Interested school students and research establishments, more Lecture in association with were able to take part in a choice than 60 demonstrations of future- the RWTH Colloquium on Laser of 15 workshops and visits to com- oriented laser technology applica- Technology panies, allowing them to obtain a tions were carried out at the Fraun- Prof. Klaus M. Radermacher, real-life view of the world of optical hofer ILT and by companies from Lehrstuhl für Medizintechnik, technologies. A varied selection of the Laser Application Center to illus- RWTH Aachen topics including laser technology, trate state-of-the-art systems and »Computergestützte Chirurgie – lighting systems for cars, and medi- processes. An exhibition area with Stand der Technik und Trends« cal engineering, enabled the stu- 34 exhibitors provided an ideal sett- dents to awaken previously undis- ing for the exchange of information 02. - 05.05.2006, Aachen covered skills and talents, and to and professional opinions. Schools event reinforce existing interests with a »The Fascination of Light« view to future professional training A new feature of AKL´06 was the From May 2 to 5, 2006, over 400 and career options. extremely well-attended beginners’ school students aged 14-18 had a seminar on laser technology, held chance to learn more about optical The Fraunhofer ILT schools event on May 3, 2006. This seminar spe- technologies during an event bear- was moreover tied in with the cifically targeted companies that ing the slogan »The Fascination of nationwide initiative »Germany - had not dealt with laser technology Light«. This outreach event in Land of Ideas«, under the patro- before - neither as vendors nor as connection with the 6th Aachen nage of German president Horst users.

142 Fraunhofer ILT Annual Report 2006 Conventions and Conferences

Novices to the laser world were Colloquium for Laser Technology separate categories: »industrial able to learn in a clearly structured AKL´06. Two outstanding engineers practice« and »applied research«. format how laser machining pro- received prizes in 2006: Professor The prize-winners are selected and cesses work, what type of laser is Dr.-Ing. Horst Exner - professor of nominated on the basis of the sub- employed for different applications, physical engineering/laser engineer- mitted applications by the executive which areas of industry employ ing at Mittweida University of committee and members of the laser technology, how to determine Applied Sciences and director of association Arbeitskreis Lasertech- Above: The exhibition accom- when laser processing is a worth- Laserinstitut Mittelsachsen e. V. - nik e. V. panying the conference at AKL’06. while option, what services are for the development of laser micro- Middle above: Award of the Lasertechnik early-stage research offered by laser subcontracting sintering, and Dipl.-Ing. Stefan The Lasertechnik early-stage re- prize to Dr.-Ing., Dipl.-Wirt. Ing. firms, and what trends and prospects Wischmann - head of beam and search prize is a new prize, awarded Karsten Schneefuß (2nd from are in view for various aspects of sensor technology in the Sales/ for the first time in 2006 by the left) on May 3, 2006. Middle below: Live laser tech- laser technology. The complete pro- Engineering department of the Auto association Arbeitskreis Lasertechnik nology demonstrations at the gram, including demonstrations at Division of ThyssenKrupp Steel AG, e. V., with the aim of supporting Fraunhofer ILT during AKL’06 on the Fraunhofer ILT, can be found on Duisburg - for the development research in the field of laser techno- May 5, 2006. the ILT Web site at www.ilt.fraun- of an optical system for laser-beam logy at RWTH Aachen University by Below: Award of the Lasertechnik innovation prize to Professor hofer.de/AKL06. welding with integrated weld follow- scientists at an early stage of their Dr.-Ing. Horst Exner (2nd from left) ing for butt and fillet welds. careers. This prize is awarded to and Dipl.-Ing. Stefan Wischmann The AKL’06 conference proceedings holders of a doctorate from RWTH (3rd from left) on May 4, 2006. and the beginners’ seminar on laser The prizes, each worth 3000 euros, Aachen University, whose published technology, including 2 CD-ROMs were presented to the two winners doctoral thesis and accompanying containing the full set of lecture by Professor Dr. rer. nat. Reinhart project work represent a significant slides, can be ordered from the Poprawe M.A. - deputy chairman of contribution to the advancement of publisher, VDI Verlag GmbH, at Arbeitskreis Lasertechnik e.V. and application-oriented laser technolo- the following Internet address: director of the Fraunhofer Institute gy, and at the same time promise www.vdi-nachrichten.com/buchshop for Laser Technology ILT, Aachen – to be of considerable utility value (search key: AKL). and by Dr. Bernd Schulte - president to industry. of the European Photonics Industry 03.05.2006, Aachen Consortium EPIC, vice-president of Further information on the prize- Technology Business Day TBT the European Technology Platform winners can be found on the Web To complement the specialist tech- for optical technologies Photonics21, site of the association Arbeitskreis nical conference at AKL’06, entre- and executive vice-president, COO Lasertechnik e. V. at www.akl-ev.de. preneurs and business executives of Aixtron AG, Aachen. were given an opportunity to gather 05.05.2006, Aachen an overview of current market At the opening of AKL´06 one day 23rd seminar of the »Aix Laser trends in laser technology, auto earlier, on May 3, 2006, the Laser- People« manufacturing and machine tools. technik early-stage research prize the alumni club of the Fraunhofer The Technology Business Day that was presented at a ceremony in the ILT and the Chair for Laser Techno- took place on May 3, 2006, focused Ludwig Forum Aachen to Dr.-Ing. logy LLT, including an opportunity on non-technical content, taking Dipl.-Wirt. Ing. Karsten Schneefuß to watch over 60 live demonstrations in such subjects as financing, legal - assistant to the director of the in the ILT Laser Applications Center aspects, human resources, market- electronics division of Hella KGaA in connection with the AKL’06 con- ing, distribution, and strategy, in Hueck & Co., Lippstadt - for the ference. a series of 13 lectures. The full pro- development of a hybrid test system gram can be found on the Fraun- for in-situ form and roughness 11.05.2006 hofer ILT Web site at www.ilt.fraun- measurement of microstructured Chair for Laser Technology LLT hofer.de/TBT06. optical functional surfaces, while at RWTH Aachen working on his doctoral thesis at Lecture in association with The TBT’06 proceedings including a the Chair of Metrology and Quality the RWTH Colloquium on Laser CD-ROM containing the speakers’ Management at RWTH Aachen Technology lecture slides, can be obtained from University. Prof. Philip Russell, Institut für Optik, the customer service department Universität Erlangen-Nürnberg of the WirtschaftsWoche magazine The Lasertechnik innovation prize is »Photonic crystal fibres (PCFs)« at the following Internet address: awarded at 2-yearly intervals by the www.wiwo-shop.de. association Arbeitskreis Lasertech- 23.05.2006, Aachen nik e. V., Aachen, to two selected Unihits for Kids 03. and 04.05.2006, Aachen individuals whose exceptional skills Forum organized by the Chair Presentation of the 2006 Laser- and dedicated work have led to for Laser Technology LLT and the technik innovation and early- innovations in laser technology. Fraunhofer ILT to give advice on stage research prizes Through the award of this prize, a scientific careers to students at the The Lasertechnik innovation prize spotlight is focused on the interface GGS Laurensberg. awarded by the association Arbeits- between scientific research and kreis Lasertechnik e. V. was presen- industrial practice. Given the intrinsic ted to the winners in a ceremony differences between these two at the Aula Carolina zu Aachen on areas of activity, applications for the May 4, 2006, during the Aachen innovation prize are judged in two

Fraunhofer ILT Annual Report 2006 143 Conventions and Conferences

31.05.2006, Aachen 22.09.2006, Hamburg 23.11.2006, Aachen Aachen Laser Seminar 24th seminar of the »Aix Laser Aachen Laser Seminar »Advance by laser surface People« »Laser metrology for the engineering - deposition welding, the alumni club of the Fraunhofer metalworking industry« repairs, cleaning and polishing« ILT and the Chair for Laser Techno- Seminar organized by Carl Hanser Seminar organized by Carl Hanser logy LLT, featuring a presentation of Publishers, Munich in association Publishers, Munich in association the company PS Laser GmbH & Co. with the Fraunhofer Institute with the Fraunhofer Institute for KG, Thedinghausen, by Dipl.-Ing. for Laser Technology ILT, Aachen. Laser Technology ILT, Aachen. Lutz Abram, followed by a visit to Additional information: Additional information: the company’s premises, and ano- www.aachenerlaserseminare.de. www.aachenerlaserseminare.de. ther visit to Rofin-Sinar Laser GmbH in Hamburg, where a lecture was 07.12.2006 01.06.2006 held by the company’s managing Chair for Laser Technology LLT Chair for Laser Technology LLT director Dipl.-Ing. Thorsten Frauen- at RWTH Aachen at RWTH Aachen preiß on the subject of »Innovation Lecture in association with the Lecture in association with processes at Rofin-Sinar«. RWTH Colloquium on Laser the RWTH Colloquium on Laser Technology Technology 27.09.2006, Aachen Hans-Joachim Cappius, Laser- und Prof. Karsten König, Fraunhofer- Unihits for Kids Medizin-Technologie GmbH, Berlin Institut für Biomedizinische Technik Forum organized by the Chair »Optische Technologien in der IBMT, St. Ingbert for Laser Technology LLT and the Medizintechnik« »Multiphotonen-Tomographie und Fraunhofer ILT to give advice on Nanochirurgie mittels Femtosekun- scientific careers to students at the 13.12.2006, Aachen den-Laser« Couven-Gymnasium. Unihits for Kids Forum organized by the Chair 08.06.2006 03.11.2006, Aachen for Laser Technology LLT and the Chair for Laser Technology LLT 25th seminar of the »Aix Laser Fraunhofer ILT to give advice on at RWTH Aachen People« scientific careers to students at the Lecture in association with the the alumni club of the Fraunhofer Otto-Hahn-Gymnasium in Mon- RWTH Colloquium on Laser ILT and the Chair for Laser Techno- heim am Rhein. Technology logy LLT, featuring lectures by Dr. Prof. Thomas Schmitz-Rode, Institut Arnold Gillner, Fraunhofer ILT, on 14.12.2006 für Biomedizinische Technologien, »Laser applications in the field of Chair for Laser Technology LLT RWTH Aachen medical engineering at the Fraun- at RWTH Aachen »Mikro- und Nanomedizin: Heraus- hofer ILT«, and by Dr. Hubert Kunze, Lecture in association with forderungen und Chancen für die Boehringer Ingelheim micro-Parts the RWTH Colloquium on Laser Medizintechnik« GmbH, Dortmund, on »Respimat® Technology Soft Inhaler: The development of an Dr. Frieder Loesel, Perfect Vision 21.06.2006, Aachen innovative inhaler for the treatment Optische Geräte GmbH, Heidelberg Unihits for Kids of respiratory problems«. The lec- »Ultrakurzpulslaser in der Medizin - Forum organized by the Chair tures were followed by a visit to the Sanftes Licht für präzise Therapie« for Laser Technology LLT and the Philips research center in Aachen. Above: Lecture at the »Aachen Laser Seminar«. Fraunhofer ILT to give advice on 21.12.2006, Aachen Middle: Demonstrations at the scientific careers to students at the 20.11. - 21.11.2006, Aachen 26th seminar of the »Aix Laser »Aachen Laser Seminar«. Gymnasium Baesweiler. Aachen Laser Seminar People« Below: 24th seminar of the »Aix Laser People« in Thedinghausen. »Online quality assurance of the alumni club of the Fraunhofer 06.07.2006 laser joining processes – reliable ILT and the Chair for Laser Techno- Chair for Laser Technology LLT and efficient laser-beam welding« logy LLT, featuring lectures by Dr. at RWTH Aachen Seminar organized by Carl Hanser Willi Neff, Fraunhofer ILT, on »New Lecture in association with Publishers, Munich in association developments from the department the RWTH Colloquium on Laser with the Fraunhofer Institute of plasma technology at the Fraun- Technology for Laser Technology ILT, Aachen. hofer ILT«, by Dr. Rainer Lebert, Prof. Peter Hering, Additional information: managing director of AIXUV Forschungszentrum »Caesar«, Bonn www.aachenerlaserseminare.de. GmbH, Aachen, on the subject of »Moderner Lasereinsatz in Medizin, »AIXUV GmbH - short-wavelength Umwelt und Life Science« 22.11.2006, Aachen emissions (EUV) in industry and Aachen Laser Seminar science«, and by Dr. Joseph Pan- 20.07.2006 »Innovative laser cutting and kert, Philips Lighting B.V., Eindho- Chair for Laser Technology LLT welding processes for metal ven, on »Philips Extreme UV GmbH at RWTH Aachen machining applications« - lithography plants for the next Lecture in association with the Seminar organized by Carl Hanser generation of integrated circuits«. RWTH Colloquium on Laser Publishers, Munich in association The lectures were followed by visits Technology with the Fraunhofer Institute to the premises of AIXUV GmbH Dr. Holger Lubatschowski, Laser for Laser Technology ILT, Aachen. and Philips Extreme UV GmbH in Zentrum Hannover, Bereich Medizin/ Additional information: Aachen. Biophotonik www.aachenerlaserseminare.de. »Anwendungspotential ultrakurzer Laserpulse in Medizin und Life science«

144 Fraunhofer ILT Annual Report 2006 Trade Fairs

21.03. - 23.03.2006 24.10. - 28.10.2006 Shanghai, China Hannover LASER. World of Photonics China EuroBLECH International trade show and International Sheet Metal Working congress Technology Exhibition Participation by the Fraunhofer ILT Participation by the Fraunhofer ILT at the group stand hosted by Messe system technology department at München, the Fraunhofer-Gesellschaft group ILT topic: laser beam sources and stand, applications. ILT topic: process monitoring in laser materials processing. 24.04. - 28.04.2006 Hannover 07.11. - 09.11.2006 Hannover Messe 2006 Friedrichshafen International show for industrial parts2clean technologies Trade Fair for Parts Cleaning and The micro technology department Drying Technology of the Fraunhofer ILT exhibited at Participation by the Fraunhofer ILT the group stand hosted by IVAM, surface treatment department ILT topic: lasers in micro technology, at the group stand hosted by the exhibit: spiral drilling optics. Fraunhofer Cleaning Technology Network, ILT topic: laser-beam cleaning. 09.05. - 12.05.2006 Sinsheim 15.11. - 17.11.2006 Microsys Düsseldorf Congress and exhibition on micro- ComPaMED systems engineering and precision International Trade Fair for Com- manufacturing, ponents, Parts and Raw Materials Participation by the Fraunhofer ILT for Medical Manufacturing micro technology department, Participation by the Fraunhofer ILT ILT topic: laser-beam micromachining. micro technology and surface treat- Above: Hannover Messe 2006. Minister Prof. Dr. Andreas Pinkwart ment departments at the IVAM (right) und Dipl.-Ing. Welf Wawers 13.06. - 16.06.2006 group stand, (Fraunhofer ILT). Oyonnax, France ILT topics: laser-beam transmission Middle: INSITE 06, Johannesburg, FIP 2006 welding of plastics without the South Africe. From left: Mosibudi Mangena, South African Minister International Plastics Industry addition of absorbers, microdrilling of Science and Technology, Exhibition FIP of holes for dosing devices and the Fraunhofer senior vice-president Participation by CLFA at the group fixing of implants, and the fabrica- Dr. Alfred Gossner, Olaf Köndgen, DAAD Bonn, Dr. Stefan Kaierle, stand hosted by the company SMT, tion of implants by means of selec- Fraunhofer ILT. CLFA topics: laser applications tive laser melting. Below: Fraunhofer ILT stand at for die- and tool-making, and the ComPaMED 2006, Düsseldorf. potential of selective laser melting (SLM) as a method of direct manu- facturing.

24.09. - 27.09.2006 Johannesburg, South Africa INSITE 06 International Science, Innovation and Technology Exhibition Participation by the Fraunhofer ILT system technology department at the group stand hosted by BMBF and DAAD, ILT topic: applications in the fields of welding and generation.

Fraunhofer ILT Annual Report 2006 145 Publications

»Your partner for innovation« Proceedings of the Technology (German/English) Business day TBT’06 This brochure provides a concise over- The proceedings of the Technology view of the Fraunhofer ILT. In addition Business Day, which took place on to presenting a summary of European 03.05.2006 in Aachen with a panel R&D projects conducted by the ILT, the of 13 experts in financial services, brochure also contains a short profile technology marketing, law, sales and of the institute as well as a list of refe- business consulting, are addressed pri- rence customers. marily toward managers of expanding TAGUNGSBAND high-tech firms and newly established »Services and Contacts 2006/7« small companies. The publication pro- (German/English) vides a succinct overview of the emerg- This brochure gives an overview of ing trends and opportunities offered by current services offered and contacts laser technology, mechanical and auto- within the Institute. It also introduces motive engineering. At the same time, focal points of each division of the it also sheds light on many financial, Fraunhofer ILT. legal and marketing questions confront- ing businesses at various stages of their Annual Report 2006 evolution.

03.- 05. MAI 2006 (German/English) The annual report presents a compre- Technical Brochure: EUROGRESS AACHEN hensive look at the R&D activities of »High-Power Diode Lasers« the Fraunhofer ILT for the respective This technical brochure outlines the ILT business year. Lists of scientific publi- various development activities of the Fraunhofer Institut Lasertechnik cations and lectures as well as patents, Fraunhofer ILT in the area of high- dissertations, conferences and trade power diode lasers. Included are fairs are also included. The English ver- developments such as the design of sion can only be found on our website special components for laser cooling, at: www.ilt.fraunhofer.de. diode laser bar packaging, diode laser burn-in characterization and the optical Proceedings of the Aachen Collo- design and development of complete quium for Laser Technology AKL’06 diode laser modules. The technical proceedings of the Aachen Colloquium for Laser Techno- logy AKL’06 (May 3 - 5, 2006) contains reports from 34 laser manufacturers and users outlining the latest develop- ments and technology trends in in- dustries such as optics, automobile, metal production, tool and die making as well as electrical and electronic engineering. Practical case studies highlight various laser processes such as laser beam welding and cutting, laser surface technology as well as laser micro engineering.

146 Fraunhofer ILT Annual Report 2006 Publications

Technical Brochure: »LASIM® - Technical Brochure: »Rapid Proto- Laser Simulator for Training« typing and Rapid Manufacturing This technical brochure gives an of Metal Parts« overview of the advantages of using This brochure describes the selective multimedia software to train laser laser melting process developed at the users and students. It introduces the Fraunhofer ILT which enables complex application fields, program contents metal parts to be manufactured directly and the system demands of the LASIM® from 3D CAD data. It also provides software. This was developed at the examples of applications of the laser Fraunhofer ILT for the training of laser beam generation technique. welding and cutting. The LASIM® CD ROM with corresponding program Technical Brochure: instructions is available at the Fraunhofer »Lasers in Microstructuring« ILT. This technical brochure describes processes such as laser ablation, Technical Brochure: »Laser Tech- precision cutting, drilling and laser- nology for Surface Modification assisted microforming. and Forming« This technical brochure provides an Technical Brochure: »Laser Ablation, overview of how lasers are employed Cleaning and Marking« in the area of surface modification and This technical brochure outlines forming. Included are processes such the advantages of the different laser as deburring, melting and forming, processes and the wealth of potential polishing, roughening, structuring and applications. activation, re-crystallization, annealing and fine pearlitizing. Technical Brochure: »Systems and Equipment for Laser Materials Technical Brochure: »Laser Processing« Technology for Wear and Corrosion This technical brochure highlights the Protection« systems engineering solutions available Wear and corrosion protection can be to Fraunhofer ILT customers. They created by various laser processes. This encompass the planning, development technical brochure provides insights and installation of complete laser into processes such as martenistic sur- facilities and process monitoring and face hardening, remelting, deposition control systems, complemented by fea- welding, alloying and dispersion. sibility studies, training and education seminars and consulting services. Technical Brochure: »Laser Beam Deposition Welding« Technical Brochure: »Quality Assu- This technical brochure provides an rance in Laser Materials Processing« introduction to the processes and This technical brochure explains the systems used in laser beam deposition potential for process monitoring and Lasertechnik für welding. It also elucidates the differen- control in laser materials processing. It die Oberflächen- modifikation und ces between conventional powder also outlines the services available from das Umformen feed nozzles and those used in laser the Fraunhofer ILT for the development beam deposition welding. of such monitoring systems.

Fraunhofer ILT Annual Report 2006 147 Publications

Technical Brochure: Information Brochure: »Lasers in Mounting and Connecting »Optical Technology Courses Techniques« at RWTH Aachen« This technical brochure gives an over- This brochure summarizes the laser view of the use of laser technology in technology courses available at RWTH mounting and connecting techniques. Aachen and is designed specifically for Micro joining processes such as laser students of mechanical and electrical beam bonding and laser beam solder- engineering as well as physics. The ing are demonstrated. brochure details the courses and lectures on laser technology available to students Technical Brochure: »Lasers within their major field of study that are in Plastics and Paper Processing« taught by the individual RWTH chairs This technical brochure describes the under the auspices of the Fraunhofer ILT. use of lasers in the processing of plastics, composite materials, paper and glass. Information Brochure: »Networks of Competence« Laser in der Kunststoff- und Papiertechnik Technical Brochure: »Lasers »Networks of Competence« was set in Life Science« up on the initiative of the BMBF and This technical brochure deals with serves as an international marketing applications of laser technology in instrument and presentation showcase medical engineering. It also describes for the most highly skilled networks of the use of lasers as tools in microreac- competence in Germany. Its Internet tion processes and biotechnology. portal, at: www.kompetenznetze.de, with its efficient search engine and Technical Brochure: many useful links, provides an ideal »Modeling and Simulation« information source and communica- Written by experts, this brochure pro- tion platform for individuals and orga- vides an overview of the activities and nizations in Germany and elsewhere core competencies of the project looking for information and potential group on modeling and simulation. ILT working partners. specialists and researchers at the Chair for Laser Technology LLT of RWTH Information Brochure: Aachen University devise models to »European Laser Institute ELI« simulate resonator design concepts This brochure provides information on and beam-guiding and focusing the European network of recognized systems, and a variety of machining centers of R&D in laser technology processes including cutting, welding coordinated by the Fraunhofer ILT. and drilling. The members of this network have set themselves the goal of making existing Technical Brochure: laser know-how in Europe accessible »Laser Microscopy« to all interested parties in industry Laser in Life Science A brochure offering insights into and science. The project is sponsored advanced techniques of laser scanning by the European Commission. Further microscopy developed at the Fraun- information can also be found at: hofer ILT. www.europeanlaserinstitute.org.

Product and Project Data Descriptions of projects from the Fraunhofer ILT annual reports and specific product information can be downloaded from our website at: www.ilt.fraunhofer.de.

148 Fraunhofer ILT Jahresbericht 2005 Technical Book »Laser Technology for Manufacturing«

Contents »Laser technology for manufac- Introduction, behavior of electromag- turing« by Reinhart Poprawe netic radiation at interfaces, absorption of laser radiation, energy transfer and Principles, prospects and examples thermal conduction, thermomechanics, for the innovative engineer. phase transformation, melting pool flows, laser-induced ablation, plasma Applied laser technology is too wide- physics, laser radiation sources, surface ranging a topic to be covered in a technologies, forming, rapid prototyp- single volume. For this reason, the ing, rapid tooling, joining, ablation and book places special emphasis on laser drilling, cutting, systems engineering, technology as used in manufacturing laser measuring technologies. applications, particularly present-day Appendices: A: optics, B: continuum machining processes used in produc- mechanics, C: laser-induced ablation, tion technology. The phenomena D: plasma physics, E: explanation occurring in laser-based materials pro- of symbols and constants, F: color cessing are quantified by formulae and images, index illustrated with corresponding models that are readily understood by the 2005. XVII, 526 pages, 353 illustrations trained engineer or physicist. These (VDI publication), ISBN 3-540-21406-2 basic principles enable the different types of machining operations to be The book can be ordered from: systematically characterized, permitting Springer Kundenservice the various applications to be illustra- Haberstraße 7 ted using a common scientific basis. 69126 Heidelberg Of more practical significance are the Telefon: +49 (0)6221/345-0 processes described for various machin- Fax: +49 (0)6221/345-4229 ing operations, which explain in simple [email protected] terms the basic principles and key www.springer.de quantitative interrelationships between the process parameters. The numerous examples are intended to spark the reader’s creativity and help to inspire new applications.

Fraunhofer ILT Annual Report 2006 149 Video Films and Multimedia Software

Video »Laser - the Extraordinary CD-Rom »Laser Technology« Light for Material Processing« (German only) (German/English) This CD-ROM is a collection of graphics, This training video was made at the pictures and videos from the lectures Bergische Universität - Gesamthoch- Laser Technology I and II by Prof. schule Wuppertal in cooperation with Dr. rer. nat. Reinhart Poprawe M.A. the VDI-Technologiezentrum in Düssel- and a new revised version was produced dorf, the Fraunhofer ILT and other laser in 2003. centers and companies and a new pro- duction was made in 2000. It delivers It was produced by the Department an overview of all important laser for Laser Technology LLT in the machine machining processes and was specially faculty at the Technical University made for use at colleges, universities, Aachen RWTH in close cooperation technical colleges, vocational schools with the Fraunhofer Institute for Laser and internal company training. This Technology ILT. especially applies to manufacturing engineering courses of study. The VHS It contains the basics of laser technology video is 42 minutes long and is avail- as well as physical and technical pro- able in both English and German from cesses for modern manufacturing pro- the Bergische Universität - Gesamt- cesses. Furthermore, the current state hochschule Wuppertal, Fachbereich D, of economic use of laser and industrial Abteilung Maschinenbau. applications is demonstrated in nume- rous examples. Contact: Prof. Helmut Richter The program runs using Acrobat Reader Phone: +49 (0)202/439-2042 5.0 on computers with Microsoft [email protected] Windows 95 OSR 2.0, Windows 98 SE, Windows Millenium Edition, Windows NT 4.0 with Service Pack, Windows 2000, Windows XP and MacOSX (64 MB Ram (random access memory) as well as 30 MB free fixed-disk storage).

The printing and use of unaltered graphics and pictures is only allowed for educational purposes.

Further information and order forms for the CD-ROM »Laser Technology« are available through the laser technology association AKL e.V., Steinbachstraße 15, 52074 Aachen.

Contact: Diana Heinrichs Phone: +49 (0)241/8906-122 Fax: +49 (0)241/8906-112 [email protected]

150 Fraunhofer ILT Annual Report 2006 Video Films and Multimedia Software

The advantages of using multimedia Multimedia Software LASIM® software for training of specialists and (German/Englisch) students are obvious: • Visualization of complex correlations LASIM® is a multimedia training and process development program for laser cutting and welding. • Simulation of a real laser workstation The combination of text, pictures, • Ability to carry out experiments on sound and animation within the multi- virtual systems with evaluation of media software has opened new results horizons in laser training. In the theo- • Unlimited availability and no risk retical part of the curriculum, compli- from operator error cated processes and models are vividly • Low support costs and suitability presented. This contributes to a better for private study understanding of the material. In the • Interactive theoretical and practical practical part of the training, nume- exercises to strengthen knowledge rous experiments can be made through simulations. The user can personally The software LASIM® is obtainable set the process parameters without from the Fraunhofer Institute for Laser causing problems in the real laser Technology in both German and system. English. Current information and order forms are available through the inter- By installing several computer worksta- net site www.ilt.fraunhofer.de. tions, personnel costs can be reduced. Furthermore, the multimedia program Contact: is suited for private study. The laser Dr. Dirk Pertring user is able to work on experiments on Phone: 49 (0)241/8906-210 the virtual system at any time. Fax: 49 (0)241/8906-121 [email protected] Multimedia technology ideally supple- ments practical training on real laser systems. In the initial phase, the exer- cises are conducted at a beginner level. In the following phases, the user is able to use the knowledge acquired to solve concrete problems on real laser systems.

Fraunhofer ILT Annual Report 2006 151 Information-Service

Sender If you would like more information Technical Brochure: »High-Power about the research and development Diode Lasers« at the Fraunhofer Institute for Laser German ______Technology please go to our website English Last Name, First Name at www.ilt.fraunhofer.de. Information ® ______can also be ordered using this form. Technical Brochure: »LASIM - Company Laser Simulator for Training« German ______Division Brochure: »Your partner English for innovation« ______German Technical Brochure: »Lasertechnik Address English für die Oberflächenmodifikation ______und das Umformen« (Laser Tech- City/ZIP Brochure: »Services and nology for Surface Modification Contacts 2006/7« and Forming) (only German) ______Phone (German/English) Technical Brochure: »Lasertechnik ______Annual Report 2006 für den Verschleiß- und Korrosions- Fax (English version only available schutz« (Laser Technology for ______online at www.ilt.fraunhofer.de) Wear and Corrosion Protection) E-mail (only German) Annual Report 2005 (English version only available Technical Brochure: Please fax to: online at www.ilt.fraunhofer.de) »Laserstrahlauftragschweißen« Fraunhofer ILT (Laser Beam Deposition Welding) Stefanie Flock Annual Report 2004 (only German) Fax: +49 (0)241/8906-121 (English version only available online at www.ilt.fraunhofer.de) Technical Brochure: »Rapid Prototyping and Rapid Annual Report 2003 Manufacturing (English version only available German online at www.ilt.fraunhofer.de) English

Proceedings of the Aachen Technical Brochure: Colloquium for Laser Technology »Lasers in Microstructuring« AKL’04 (only German) German English Proceedings of the Laser- Business-Day of the AKL’04 Technical Brochure: (only German) »Abtragen, Reinigen und Markieren mit Laserstrahlung« Proceedings of the Aachen (Laser Ablation, Cleaning and Colloquium for Laser Technology Marking) (only German) AKL’06 (only German) Technical Brochure: »Systems and Proceedings of the Technology Plant for Laser Materials Business Day TBT’06 Processing« (only German) (only German) Technical Brochure: »Quality Assurance in Laser Materials Processing« German English

152 Fraunhofer ILT Annual Report 2006 Imprint

Technical Brochure: »Lasers Editorial staff in Mounting and Connecting Dipl.-Phys. Axel Bauer (responsible) Techniques« Stefanie Flock German English Design and Production Dipl.-Des. Andrea Croll Technical Brochure: »Lasers in Polymer and Paper Technology« Print German Druckspektrum English Hirche-Kurth GbR, Aachen

Technical Brochure: Paper »Lasers in Life Science« This Annual Report was printed on German environment-friendly, unchlorinated English and acid-free bleached paper.

Technical Brochure: »Modellie- Contact rung und Simulation« (Modeling Dipl.-Phys. Axel Bauer and Simulation) (only German) Telephone: +49 (0)241/8906-194 Fax: +49 (0)241/8906-121 Technical Brochure: »Laser- [email protected] mikroskopie« (Laser Microscopy) (only German) Subject to alterations in specifications and other technical information. Information Brochure: »Optische Technologien an der RWTH All rights reserved. Reprint only with Aachen« (Optical Technology written permission of the editorial office. Courses at RWTH Aachen) (only German) © Fraunhofer-Institut für Lasertechnik ILT, Aachen 2007 Information Brochure: »Networks of Competence« (German/English)

Information Brochure: »European Laser Institute ELI« (only English)

CD-Rom »Lasertechnik« (Laser Technology) (only German)

Technical Book »Lasertechnik für Fraunhofer-Institut die Fertigung« (Laser Technology für Lasertechnik ILT for Manufacturing) (only German) Steinbachstraße 15 Multimedia Software LASIM® 52074 Aachen German Telephone: +49 (0)241/8906-0 English Fax: +49 (0)241/8906-121

[email protected] www.ilt.fraunhofer.de

Fraunhofer ILT Annual Report 2006 153