DOCSLIB.ORG

Applications of Laser Spectroscopy Constitute a Vast Field, Which Is Difficult to Spectroscopy Cover Comprehensively in a Review

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Applications of Laser Spectroscopy Constitute a Vast Field, Which Is Difficult to Spectroscopy Cover Comprehensively in a Review LASERS & OPTICS 151 many cases non-destructively. A variety of beam manipulation schemes are avail­ able for the irradiation of samples either directly or after preparation. The unique properties of laser radiation in terms of coherence, intensity and directionality permit remote chemical sensing, where the analytical equipment and the sample are separated by large distances, even of several kilometres. Absorption, and in particular differential absorption, can be utilised in long-path measurements, whereas elastic and inelastic backscatter- ing as well as fluorescence can be used for range-resolved radar-like measure­ ments (LIDAR: light detection and rang­ ing). Laser light can also be efficiently transported in optical fibres to remotely located measurement sites. Various prop­ erties of the fibre itself influence the laser light propagating through the fibre, thus Applications of Laser forming a basis for fibre optic sensors. Applications of laser spectroscopy constitute a vast field, which is difficult to Spectroscopy cover comprehensively in a review. Rather than attempting such a review, examples from a variety of fields are cho­ Costas Fotakis sen for illustrating the power of applied University of Crete, Greece laser spectroscopy. Sune Svanberg Lund Institute of Technology, Sweden Applications in Analytical Chemistry Laser spectroscopy is making a major impact in many traditional fields of ana­ As the new millennium approaches the Above The Italian research vessel Urania, carrying a lytical spectroscopy. For instance, opto- know how in the field of laser-matter Swedish laser radar system, which has sailed under the galvanic spectroscopy on analytical smoky plumes of Sicilian volcanos in Italy measuring the interactions has matured to the stage of sulphur dioxide content flames increases the sensitivity of enabling several exciting real life applica­ absorption and emission flame spec­ tions. Several of these applications rely In recent years, laser sources have troscopy. Extremely sensitive direct on the narrow bandwidth of tuneable become more rugged, easy-to-use and absorption measurements with CW lasers lasers, which allows extreme selectivity in cheaper to allow real world applications can be performed using frequency-mod­ the interaction with free atoms and mole­ of laser spectroscopy. Semiconductor ulation spectroscopy with a t:107 absorp­ cules. In other applications, the high diode lasers have become very reliable tion sensitivity. A high sensitivity in spectral intensity available with pulsed as and easily accessible, and their wave­ absorption can also be achieved in intra­ well as continuous wave (CW) lasers may length range is extended higher and cavity experiments. saturate optical transitions or induce a higher up into the visible region. We can Traces of material can be detected variety of nonlinear effects, as for exam­ mention the emerging blue diode lasers using the REMPI (Resonance Enhanced ple multiphoton ionisation, thus provid­ based on gallium phosphide, and fre­ Multi-Photon Ionisation) or RIMS ing the basis for highly sensitive detec­ quency conversion of the output of reli­ (Resonance Ionisation Mass Spectros­ tion schemes. In fact, single-atom or mol­ able, high-power diode lasers into new copy) techniques, both employing pulsed, ecule detection is widely used, represent­ wavelength regions. New laser materials, tuneable lasers. In the first method, selec­ ing the ultimate sensitivity in analytical such as titanium-doped sapphire, allow tively produced ions of the element are chemistry. In a different trend, ultrafast all-solid-state tuneable systems with con­ detected through the ion current, where­ lasers have allowed detailed temporal siderable power to be constructed. as the second method employs a mass monitoring of chemical reaction dynam­ Diode-laser pumping of solid-state mate­ spectrometer for additional selectivity. ics at femtosecond timescales (femto- rials is making flash-lamp pumping grad­ The breadth of standard analytical- chemistry). In this way, significant insight ually obsolete and enables compact, reli­ chemistry techniques can be further into the basic steps of chemical processes able and energy-efficient laser sources, improved through laser spectroscopy, has been gained. Finally, in the form of especially when combined with current employed for enhanced detection sensi­ holographic techniques the coherence frequency conversion schemes (eg optical tivity and multiplexing. Thus, laser- properties of laser light are the basis of parametric amplifiers). induced fluorescence (LIF) can be ultrasensitive structural diagnostics Laser-based analysis and diagnostics utilised for detecting the separated frac­ applications. can readily be performed in situ and in tions passing the detector position in 1998 July/August News Europhysics 152 LASERS & OPTICS Fig 1 Left The Italian volcano Stromboli, seen from the research vessel Urania Below The volcanic plume of Mt Etna as recorded by laser radar techniques in September1994 during a ship-borne traverse under the plume, integrated vertical and horizontal profiles of sulphur dioxide are shown.The total flux was 44 tonnes/hour HPLC (High Performance Liquid Combustion Processes package by a laser pulse (repumping or Chromatography) and Capillary Combustion remains the most important dissociating the molecules) and then Electrophoresis. Further, a whole section means of energy conversion. Laser spec­ identify the package position at a later of the column can be illuminated and the troscopy provides a very powerful, non- time using a second laser pulse. fluorescence along the column can be intrusive measurement capability for the CARS (Coherent Anti-Stokes Raman imaged on a linear array or a CCD detec­ reactive and aggressive media constituted Scattering) is a powerful technique, espe­ tor, to provide simultaneous detection of by burning or exploding combustion cially for temperature measurements in all species undergoing separation. gases. A large number of techniques has strongly luminous media. A coherent, Differences in fluorescence spectra can provided new possibilities to measure the laser-like beam is obtained carrying the also be utilised for further discrimina­ concentration of species including short­ signal, making it largely immune to the tion. Fluorescence labelling can be used, lived radicals, and also the capability of background light. By single-shot CARS detecting simultaneously chromophores determining temperature and flow speed. recordings, PDFs (Probability Density with different fluorescence characteristics The measurements have allowed a realis­ Functions) for temperature can be deter­ and binding to different positions in the tic interplay with the advanced kinetic mined, yielding important information DNA strand. These developments are computer codes that are used for model­ on statistical fluctuations in turbulent very important, for example for the ling combustion. Important issues in combustion. Realistic measurements on Human Genome Project. combustion include NOx and soot forma­ test engines, jet engines and even coal- Laser ablation which occurs upon the tion, engine ignition and engine knock. fired power plants have been performed. interaction of intense laser radiation with LIF has been extensively used, also in Polarisation spectroscopy and DFWM solid targets has provided a number of imaging configurations, to monitor the (Degenerate Four-Wave Mixing) spec­ novel analytical schemes in combination distribution of molecules such as OH, C2, troscopy are further powerful techniques with mass spectrometric or optical detec­ CH and CN. Using a gated and image- in combustion diagnostics. tion. Along these lines, there are several intensified CCD detector the full distrib­ The methods developed for combus­ industrial applications, in which on-line ution can be captured using a single laser tion diagnostics are also applicable for monitoring may occur by laser-induced shot ( = 10-8s). To this end, a sheet of light the monitoring of other reactive media breakdown spectroscopy (LIBS). This tech­ is formed through the burning medium such as in plasma etching or MOCVD nique exploits changes in the emission using cylindrical optics. In a similar way, (Metal Organic Chemical Vapour spectra of laser-produced plasmas depend­ recordings using transitions starting in Deposition) for semiconductor process­ ing on the stage and quality of processing. states with a temperature-dependent ing. In a relevant recent application LIBS has population can obtain temperature dis­ been applied on polymer samples for the tributions. Flow velocities are evaluated Monitoring of the Atmosphere identification and separation of polymeric using Doppler shifts in the recorded sig­ The atmosphere can be monitored by materials for recycling purposes. nals. A further method is to mark a gas laser techniques employing absorption or Fig 2 Fluorescence imaging of the northern gate of the Lund Cathedral. Images were recorded through pass- bands centred at 438 and 682 nanometers using a scanning laser radar system positioned about 50 meters from the gate. A normal colour photo­ graph of the gate Is Europhysics News July/August 1998 July/August News Europhysics shown centre LESERS & OPTICS153 Fig 3 Above A restored area on a painting is differentiated with respect to the original and analysed by using quantitative fluorescence multispectral imaging— in visible light no difference is observed. The characterization of the image relies on a narrow
Load more

Recommended publications
  • Simultaneous Intensity Profiling of Multiple Laser Beams Using the Bladecam-XHR Camera
    Simultaneous Intensity Profiling of Multiple Laser Beams Using the BladeCam-XHR Camera Shaun Pacheco College of Optical Sciences, University of Arizona Rongguang Liang College of Optical Sciences, University of Arizona Rocco Dragone Vice President of Engineering, DataRay, Inc. Real-Time Profiling of Multiple Laser Beams There are several applications where the parallel processing of multiple beams can significantly decrease the overall time needed for the process. Intensity profile measurements that can characterize each of those beams can lead to improvements in that application. If each beam had to be characterized individually, the process would be very time consuming, especially for large numbers of beams. This white paper describes how the BladeCam-XHR can be used to simultaneously measure the intensity profile measurements for multiple beams by measuring the diffraction pattern from a diffraction grating and the intensity profile from a 3x3 fiber array focused using a 0.5 NA objective. Diffraction Gratings Diffraction gratings are periodic optical components that diffract an incident beam into several outgoing beams. The grating profile determines both the angle of the diffracted beam modes and the efficiency of light sent into each of those modes. Grating fabrication errors or a change in the incident wavelength can significantly change the performance of a diffraction grating. The BladeCam- XHR, Figure 1, can be used to measure the point spread function (PSF) of each mode, the relative efficiency of each mode and the spacing between diffraction modes. Figure 1 BladeCam-XHR Using the BladeCam-XHR for Diffraction Grating Evaluation The profiling mode in the DataRay software can be used to evaluate the performance of a diffraction grating.
    [Show full text]
  • Hair Reduction by Laser
    Ames Locations To Eldora, Iowa Falls, McFarland Clinic North Ames Story City, Urgent Care Webster City Treatment McFarland Clinic (3815 Stange Rd.) Bloomington Road McFarland Clinic Physical Therapy - Somerset West Ames e. (2707 Stange Rd., Suite 102) 24th Street Av f e. Duf Av You should not use any Accutane (a prescribed oral US 69 Ontario Street 13th Street Grand 13th Street acne medication) or gold medications (for arthritis) McFarland Clinic (1215 Duff) MGMC - North Addition for six months prior to a treatment. You should William R. Bliss Cancer Center 12th Street Stange Road . e. Mary Greeley Medical Center (MGMC) McFarland Eye Center not use retinoids (e.g. Retin A, Fifferin, Differin, Av (1111 Duff Ave.) (1128 Duff) e. 11th Street Ramp Av McFarland Family Avita, Tazorac), alpha-hydroxy acid moisturizers, Medicine East Hyland St Medical Arts Building (1018 Duff) To Boone, Carroll I-35 bleaching creams (hydroquinone) or chemical peels Iowa State (1015 Duff) Jefferson N. Dakota Marshall University for two weeks prior to a treatment. Do not pluck the Lincoln Way Lincoln Way Express Care Express Care hairs, wax or use depilatories or electrolysis for six e. (3800 Lincoln Way) (640 Lincoln Way) weeks prior to a treatment. Av McFarland Clinic West Ames Hy-Vee (3600 Lincoln Way) Hy-Vee e. Av ff You may be asked to shave the area prior to your S. Dakota To Nevada, Du first treatment appointment. You may also be Marshalltown prescribed a topical anesthetic (numbing) cream to Highway 30 help reduce any discomfort the laser may cause. Blvd University First Treatment: The laser will be used to treat the N areas by your dermatologist or one of the trained Oakwood Road Airport Road dermatology staff.
    [Show full text]
  • Laser Pointer Safety About Laser Pointers Laser Pointers Are Completely Safe When Properly Used As a Visual Or Instructional Aid
    Harvard University Radiation Safety Services Laser Pointer Safety About Laser Pointers Laser pointers are completely safe when properly used as a visual or instructional aid. However, they can cause serious eye damage when used improperly. There have been enough documented injuries from laser pointers to trigger a warning from the Food and Drug Administration (Alerts and Safety Notifications). Before deciding to use a laser pointer, presenters are reminded to consider alternate methods of calling attention to specific items. Most presentation software packages offer screen pointer options with the same features, but without the laser hazard. Selecting a Safe Laser Pointer 1) Choose low power lasers (Class 2) Whenever possible, select a Class 2 laser pointer because of the lower risk of eye damage. 2) Choose red-orange lasers (633 to 650 nm wavelength, choose closer to 635 nm) The National Institute of Standards and Technology (NIST) researchers found that some green laser pointers can emit harmful levels of infrared radiation. The green laser pointers create green light beam in a three step process. A standard laser diode first generates near infrared light with a wavelength of 808nm, and pumps it into a ND:YVO4 crystal that converts the 808 nm light into infrared with a wavelength of 1064 nm. The 1064 nm light passes into a frequency doubling crystal that emits green light at a wavelength of 532nm finally. In most units, a combination of coatings and filters keeps all the infrared energy confined. But the researchers found that really inexpensive green lasers can lack an infrared filter altogether. One tested unit was so flawed that it released nine times more infrared energy than green light.
    [Show full text]
  • Solid State Laser
    SOLID STATE LASER Edited by Amin H. Al-Khursan Solid State Laser Edited by Amin H. Al-Khursan Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published chapters even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Iva Simcic Technical Editor Teodora Smiljanic Cover Designer InTech Design Team First published February, 2012 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from [email protected] Solid State Laser, Edited by Amin H.
    [Show full text]
  • American Society for Laser Medicine and Surgery Abstracts 1 AMERICAN SOCIETY for LASER MEDICINE and SURGERY
    American Society for Laser Medicine and Surgery Abstracts 1 AMERICAN SOCIETY FOR LASER MEDICINE AND SURGERY ABSTRACTS Conclusion: These initial data suggest that AFxL pre-treatment CUTANEOUS LASER is likely to enhance the uptake of IngMeb in the skin. This might enable treatment of hyperkeratotic lesions as well as increase SURGERY overall efficacy when treating AK’s with IngMeb. #2 #1 SPLIT FACE COMPARISON OF THE EFFECTS OF FRACTIONAL LASER-MEDIATED DELIVERY OF VITAMIN CE FERULIC FORMULA SERUM TO INGENOL MEBUTATE - PRELIMINARY RESULTS DECREASE POST-OPERATIVE RECOVERY AND FROM AN IN VITRO FRANZ CELL STUDY INCREASE NEOCOLLAGENOSIS IN FRACTIONAL Andre´s M. Erlendsson, Elisabeth H. Taudorf, ABLATIVE LASER RESURFACING FOR Andre´ H. Eriksson, John R. Zibert, Uwe Paasch, PHOTODAMAGE R. Rox Anderson, Merete Haedersdal Jill Waibel, Adam Wulkan Bispebjerg Hospital, University of Copenhagen, Copenhagen, Miami Dermatology & Laser Institution, Miami, FL; Denmark; LEO Pharma A/S, Ballerup, Denmark; University of Miami University, Miami, FL Leipzig, Leipzig, Germany; Wellman Center for Photomedicine, Background: New fractional ablative laser skin resurfacing is Massachusetts General Hospital, Harvard Medical School, associated with shorter periods of recovery time in comparison Boston, MA with older ablative technology. However one deterrent is the Background: Ingenol Mebutate gel (IngMeb) is a new FDA seven days of downtime associated with the procedure. Previous approved field directed treatment against Actinic Keratosis (AK). studies have shown that application of vitamin C, E and ferulic A recent study on clinically typical AK’s showed complete acid improves wound healing and promotes the induction of clearance rates of 34% for trunk and extremities, and 42% for face collagen.
    [Show full text]
  • Footprints in Laser Medicine and Surgery: Beginnings, Present, and Future
    Review Article Med Laser 2017;6(1):1-4 Review Article https://doi.org/10.25289/ML.2017.6.1.1 pISSN 2287-8300ㆍeISSN 2288-0224 Footprints in Laser Medicine and Surgery: Beginnings, Present, and Future Ki Uk Song Light-based science and technology has been evolving throughout history. One of the most significant advances in light-based science and technology is the laser. Early in its development, the laser offered Brighlans, Inc., Manila, Philippines physically unique and attractive characteristics with much potential to solve the conditions of medicine and surgery, opening many gateways for laser applicability through research by renowned physicians. In collaboration with physicians, the medical industry has continued to develop better and more efficient technological advancements. The laser has now become one of the most advanced medical solutions for a variety clinical cases. Moreover, there are some procedures for which the laser is now mandatory. Despite many challenges that still lie ahead, practitioners and patients alike are thrilled to see even more exciting progress in the fast-expanding field of laser medicine and surgery. Key words Laser; History; Selective photothermolysis; Scanning technology; Fractionated laser Received May 12, 2017 Revised June 6, 2017 Accepted June 6, 2017 Correspondence Ki Uk Song Brighlans, Inc., Heritage Tower, #1851 Vasquez Street, Malate, Manila, Philippines Tel.: +63-2-521-0441 Fax: +63-2-521-0441 E-mail: [email protected] C Korean Society for Laser Medicine and Surgery CC This is an open access article distributed under the terms of the Creative Commons Attribution Non- Commercial License (http://creativecommons.org/ licenses/by-nc/4.0) which permits unrestricted non- commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
    [Show full text]
  • Evaluation of Stimulated Raman Scattering Microscopy for Identifying Squamous Cell Carcinoma in Human Skin
    Lasers in Surgery and Medicine 45:496–502 (2013) Evaluation of Stimulated Raman Scattering Microscopy for Identifying Squamous Cell Carcinoma in Human Skin 1,2 1 1 1,3 4 Richa Mittal, MS, Mihaela Balu, PhD, Tatiana Krasieva, PhD, Eric O. Potma, PhD, Laila Elkeeb, MD, 4 1Ã Christopher B. Zachary, MBBS, FRCP, and Petra Wilder-Smith, DDS, PhD 1Beckman Laser Institute and Medical Clinic, University of California, Irvine, California 92612 2Department of Chemical Engineering and Materials Sciences, University of California, Irvine, California 92697 3Department of Chemistry, University of California, Irvine, California 92697 4Department of Dermatology, University of California, Irvine, California 92697 Background and Significance: There is a need to uncontrolled growth of epithelial keratinocytes. It is develop non-invasive diagnostic tools to achieve early and estimated that 700,000 cases of SCC are diagnosed accurate detection of skin cancer in a non-surgical manner. annually in the US, resulting in approximately 2,500 In this study, we evaluate the capability of stimulated deaths [2,3]. Although most of the non-melanoma skin Raman scattering (SRS) microscopy, a potentially non- cancer cases can be cured, rising incidence and local invasive optical imaging technique, for identifying the invasiveness constitute an important clinical challenge. pathological features of s squamous cell carcinoma (SCC) Today, non-melanoma skin cancer is diagnosed by visual tissue. inspection followed by invasive skin biopsy and histopath- Study design: We studied ex vivo SCC and healthy skin logical examination. Patients with SCC are at an increased tissues using SRS microscopy, and compared the SRS risk of future SCC tumor development, especially in the contrast with the contrast obtained in reflectance confocal same location or surrounding tissue.
    [Show full text]
  • Section 5: Optical Amplifiers
    SECTION 5: OPTICAL AMPLIFIERS 1 OPTICAL AMPLIFIERS S In order to transmit signals over long distances (>100 km) it is necessary to compensate for attenuation losses within the fiber. S Initially this was accomplished with an optoelectronic module consisting of an optical receiver, a regeneration and equalization system, and an optical transmitter to send the data. S Although functional this arrangement is limited by the optical to electrical and electrical to optical conversions. Fiber Fiber OE OE Rx Tx Electronic Amp Optical Equalization Signal Optical Regeneration Out Signal In S Several types of optical amplifiers have since been demonstrated to replace the OE – electronic regeneration systems. S These systems eliminate the need for E-O and O-E conversions. S This is one of the main reasons for the success of today’s optical communications systems. 2 OPTICAL AMPLIFIERS The general form of an optical amplifier: PUMP Power Amplified Weak Fiber Signal Signal Fiber Optical AMP Medium Optical Signal Optical Out Signal In Some types of OAs that have been demonstrated include: S Semiconductor optical amplifiers (SOAs) S Fiber Raman and Brillouin amplifiers S Rare earth doped fiber amplifiers (erbium – EDFA 1500 nm, praseodymium – PDFA 1300 nm) The most practical optical amplifiers to date include the SOA and EDFA types. New pumping methods and materials are also improving the performance of Raman amplifiers. 3 Characteristics of SOA types: S Polarization dependent – require polarization maintaining fiber S Relatively high gain ~20 dB S Output saturation power 5-10 dBm S Large BW S Can operate at 800, 1300, and 1500 nm wavelength regions.
    [Show full text]
  • Development of High-Power Optical Amplifier
    Development of High-Power Optical Amplifier by Yoshio Tashiro *, Satoshi Koyanagi *2, Keiichi Aiso *3, Kanji Tanaka * and Shu Namiki * With the development of the D-WDM (Dense Wavelength Division-Multiplex) ABSTRACT transmission technology together with its practical applications in recent years, optical amplifiers --in particular EDFA (Erbium-Doped Fiber Amplifier)-- used in these transmis- sion systems are required to have ever higher performance. In this report, a high-power EDFA is presented which has achieved a high signal output of 1.5 W. The EDFA uses a set of high power pumping light sources in which the outputs of semiconductor laser diodes in the 1480-nm range are multiplexed over three wavelengths. 1. INTRODUCTION lasers 5) of high-power at 1064 nm for example --which is pumped by GaAs semiconductor lasers at 800 nm-- as a With the development of the D-WDM transmission tech- pumping light source, thereby compensating for the low nology together with its practical applications in recent quantum conversion efficiency. What is more, intensive years, optical amplifiers --in particular the EDFA which is research 6) is going on to obtain higher outputs, in which finding wide applications- used in these transmission sys- high-power semiconductor lasers 4) at 980 nm in multi- tems are required to have higher power. This is because, mode are employed to pump a double-clad fiber. The fiber as the total power of optical signal increases due to the has a core co-doped with Er and Yb together with the first- increase in multiplexing signals, so does the power of the and second-clad layers, such that the first clad supports EDFA necessary to obtain the same level of optical gain.
    [Show full text]
  • Terahertz-Time Domain Spectrometer with 90 Db Peak Dynamic Range
    J Infrared Milli Terahz Waves DOI 10.1007/s10762-014-0085-9 Terahertz-time domain spectrometer with 90 dB peak dynamic range N. Vieweg & F. Rettich & A. Deninger & H. Roehle & R. Dietz & T. Göbel & M. Schell Received: 24 January 2014 /Accepted: 12 June 2014 # The Author(s) 2014. This article is published with open access at Springerlink.com Abstract Many time-domain terahertz applications require systems with high bandwidth, high signal-to-noise ratio and fast measurement speed. In this paper we present a terahertz time-domain spectrometer based on 1550 nm fiber laser technology and InGaAs photocon- ductive switches. The delay stage offers both a high scanning speed of up to 60 traces / s and a flexible adjustment of the measurement range from 15 ps – 200 ps. Owing to a precise reconstruction of the time axis, the system achieves a high dynamic range: a single pulse trace of 50 ps is acquired in only 44 ms, and transformed into a spectrum with a peak dynamic range of 60 dB. With 1000 averages, the dynamic range increases to 90 dB and the measurement time still remains well below one minute. We demonstrate the suitability of the system for spectroscopic measurements and terahertz imaging. Keywords terahertz time domain spectroscopy. femtosecond fiber laser. InGaAs photoconductive switches . terahertz imaging 1 Introduction Terahertz waves feature unique properties: like microwaves, terahertz radiation passes through a plethora of non-conducting materials, including paper, cardboard, plastics, wood, ceramics and glass-fiber composites [1]. In contrast to microwaves, terahertz waves have a smaller wavelength and thus offer sub-millimeter spatial resolution.
    [Show full text]
  • Application of Two-Photon Absorbing Fluorene-Containing Compounds in Bioimaging and Photodyanimc Therapy
    University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2014 Application of Two-Photon Absorbing Fluorene-Containing Compounds in Bioimaging and Photodyanimc Therapy Xiling Yue University of Central Florida Part of the Chemistry Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Yue, Xiling, "Application of Two-Photon Absorbing Fluorene-Containing Compounds in Bioimaging and Photodyanimc Therapy" (2014). Electronic Theses and Dissertations, 2004-2019. 4634. https://stars.library.ucf.edu/etd/4634 APPLICATION OF TWO-PHOTON ABSORBING FLUORENE- CONTAINING COMPOUNDS IN BIOIMAGING AND PHOTODYNAMIC THERAPY by XILING YUE B. S. Fudan University, 2009 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry in the College of Science at the University of Central Florida Orlando, Florida Fall Term 2014 Major Professor: Kevin D. Belfield ABSTRACT Two-photon absorbing (2PA) materials has been widely studied for their highly localized excitation and nonlinear excitation efficiency. Application of 2PA materials includes fluorescence imaging, microfabrication, 3D data storage, photodynamic therapy, etc. Many materials have good 2PA photophysical properties, among which, the fluorenyl structure and its derivatives have attracted attention with their high 2PA cross-section and high fluorescence quantum yield. Herein, several compounds with 2PA properties are discussed.
    [Show full text]
  • Optically Pumped Semiconductor Lasers Power
    Optically Pumped Semiconductor Lasers Power. Precision. Performance. – based on semiconductor lasers Superior Reliability & Performance History of a Breakthrough History of a Breakthrough For more than a decade, solid-state lasers have been replacing legacy gas lasers in application after application. Even solid-state lasers, with their reputation for reliability and performance, have had limitations as it relates to accessible wave- lengths and power ranges. In the late 1990’s Coherent identified the capabilities of a novel concept for a semiconductor based platform that would overcome these limitations. Investing in fundamental developments and creating an IP position, Coherent pioneered this concept and introduced the Optically Pumped Semiconductor Laser (OPSL). In 2001, the first commercial OPSL became available as a technology breakthrough. Since their beginnings, OPSLs were considered the technology of choice in a variety of applications that require true CW output – from the UV to Visible and IR. OPSL technology enables us to improve many applications that were previously limited by the fixed wavelength and power of other laser technologies. Today, with OPSL technology, you no longer have to work around the closest fit wavelength. With OPSLs, you can find the best wavelength to fit your application. OPSL Advantages and Benefits Optically Pumped Semiconductor Laser Wavelength Scalability: Responding to the need for a broad range of wavelengths in many laser applications, OPSLs with their unique wavelength flexibility, are different from any other solid-state based laser. The fundamental near-IR output wavelength is determined by the structure of the InGaAs (semiconductor) gain chip, and can be set anywhere between 920 nm and 1154 nm, yielding frequency-doubled and tripled output between 355 nm and 577 nm.
    [Show full text]