DOCSLIB.ORG

Robust Single Shot Structured Light

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Robust Single Shot Structured Light Robust Single-Shot Structured Light 3D Scanning Robuste 3D-Vermessung mit strukturierter Beleuchtung in Einzelbildern Der Technischen Fakultät der Universität Erlangen–Nürnberg zur Erlangung des Grades DOKTOR–INGENIEUR vorgelegt von Christoph Schmalz Erlangen — 2011 Als Dissertation genehmigt von der Technischen Fakultät der Universität Erlangen-Nürnberg Tag der Einreichung: 29.08.2011 Tag der Promotion: 05.03.2012 Dekan: Prof. Dr.-Ing. habil. Marion Merklein Berichterstatter: Prof. Dr.-Ing. Joachim Hornegger Prof. Dr.-Ing. Gerd Häusler Abstract In this thesis a new robust approach for Single-Shot Structured Light 3D scanning is developed. As the name implies, this measurement principle requires only one image of an object, illuminated with a suitable pattern, to reconstruct the shape and distance of the object. This technique has several advantages. It can be used to record 3D video with a moving sensor or of a moving scene. Since the required hardware is very simple, the sensor can also be easily miniaturized. Single-Shot Structured Light, thus, has the potential to be the basis of a versatile and inexpensive 3D scanner. One focus of the work is the robustness of the method. Existing approaches are mostly limited to simple scenes, that is, smooth surfaces with neutral color and no external light. In contrast, the proposed method can work with almost any close-range scene and produces reliable range images even for very low-quality input images. An important consideration in this respect is the design of the illumination pattern. We show how suitable color stripe patterns for different applications can be created. A major part of the robustness is also due to the graph-based decoding algorithm for the pattern images. This has several reasons. Firstly, any color assessments are based on ensembles of pixels instead of single pixels. Secondly, disruptions in the observed pattern can be sidestepped by finding alternative paths in the graph. Thirdly, the graph makes it possible to apply inference techniques to get better approximations of the projected colors from the observed colors. For a typical camera resolution of 780 × 580, the whole decoding and reconstruction algorithm runs at 25Hz on current hardware and generates up to 50000 3D points per frame. The accuracy of the recovered range data is another important aspect. We im- plemented a new calibration method for cameras and projectors, which is based on active targets. The calibration accuracy was evaluated using the reprojection er- ror for single camera calibrations as well as the 3D reconstruction errors for complete scanner calibrations. The accuracy with active targets compares favorably to calibra- tion results with classic targets. In a stereo triangulation test, the root-mean-square error could be reduced to a fifth. The accuracy of the combined Structured Light setup of camera and projector was also tested with simulated and real test scenes. For example, using a barbell-shaped reference object, its known length of 80.0057mm could be determined with a mean absolute error of 42µm and a standard deviation of 74µm. The runtime performance, the robustness and the accuracy of the proposed ap- proach are very competitive in comparison with previously published methods. Fi- nally, endoscopic 3D scanning is a showcase application that is hard to replicate without Single-Shot Structured Light. Building on a miniature sensor head designed by Siemens, we developed calibration algorithms and apply the graph-based pattern decoding to generate high-quality 3D cavity reconstructions. Kurzfassung In dieser Arbeit wird ein neues robustes Verfahren zur 3D-Vermessung durch Strukturierte Beleuchtung in Einzelbildern entwickelt. Dieses Messprinzip benötigt nur ein einzige Aufnahme eines mit einem geeigneten Muster beleuchteten Objekts, um dessen Form und Abstand zu rekonstruieren. Diese Technik hat mehrere Vorteile. Sie kann benutzt werden, um 3D-Videos einer bewegten Szene oder mit einem be- wegten Sensor aufzunehmen. Da sein Aufbau sehr einfach ist, ist der Sensor auch gut zur Miniaturisierung geeignet. Strukturierte Beleuchtung in Einzelbildern hat daher das Potential, als Grundlage für vielseitige und günstige 3D-Abtaster zu dienen. Ein Schwerpunkt der Arbeit ist die Robustheit der Messmethode. Existierende An- sätze sind meistens auf einfache Szenen beschränkt, das bedeutet glatte Oberflächen in neutralen Farben und kein Fremdlicht. Im Gegensatz dazu kann die vorgeschlagene Methode mit fast jeder Szene im Nahbereich umgehen und zuverlässige Tiefenkarten auch aus Eingangsbildern mit sehr niedriger Qualität erzeugen. Eine wichtige Über- legung ist in dieser Hinsicht die Gestaltung des Beleuchtungsmusters. Wir zeigen, wie geeignete Farbstreifenmuster für verschiedene Anwendungen erzeugt werden können. Ein Großteil der Robustheit beruht auch auf dem graphenbasierten Dekodierungsalgo- rithmus für die Aufnahmen des Muster. Das hat mehrere Gründe. Erstens werden alle Farbeinschätzungen anhand von Gruppen von Pixeln anstatt Einzelpixeln vorgenom- men. Zweitens können Störungen im beobachteten Muster umgangen werden, indem alternative Pfade im Graphen gefunden werden. Drittens erlaubt es der Graph, Fol- gerungstechniken anzuwenden, um bessere Näherungen für die projizierten Farben aus den beobachteten Farben zu erhalten. Mit einer üblichen Kameraauflösung von 780 × 580 läuft der gesamte Algorithmus zur Dekodierung und Rekonstruktion mit 25Hz und erzeugt bis zu 50000 3D-Punkte pro Bild. Die Genauigkeit der gewonnenen 3D-Daten ist ein weiterer wichtiger Aspekt. Wir implementierten eine neue Kalibriermethode für Kameras und Projektoren, die auf aktiven Targets basiert. Die Kalibriergenauigkeit wurde sowohl anhand des Rückpro- jektionsfehlers für Einzelkamerakalibrierungen, als auch anhand des 3D-Rekonstruk- tionsfehlers für vollständige Systemkalibrierungen ermittelt. Mit aktiven Targets wird eine höhere Genauigkeit als mit klassischen Targets erreicht. Bei einem Test durch Triangulation mit zwei Kameras konnte der mittlere quadratische Fehler auf ein Fün- ftel reduziert werden. Die Genauigkeit des Aufbaus zur Strukturierten Beleuchtung aus Kamera und Projektor wurde ebenfalls ausgewertet. Die bekannte Länge eines hantelförmigen Referenzobjekts von 80.0057mm konnte mit einem mittleren Fehler von 42µm und einer Standardabweichung von 74µm bestimmt werden. Die Rechenzeit, die Robustheit und die Genauigkeit der vorgeschlagenen Mess- methode sind im Vergleich mit bisherigen Ansätzen sehr konkurrenzfähig. Eine Vorzeigeanwendung ist die endoskopische 3D-Abtastung, die ohne die Technik der Strukturierten Beleuchtung in Einzelbildern schwer umzusetzen ist. Aufbauend auf einem von Siemens entworfenen Miniatur-Sensorkopf entwickelten wir Kalibrierver- fahren und wenden die graphenbasierte Musterdekodierung an, um hochqualitative 3D-Modelle von Hohlräumen zu erzeugen. Acknowledgement The present work is the result of my research at the Chair of Pattern Recognition of the University of Erlangen-Nuremberg and at Siemens CT T HW2 in Munich. I would like to thank Prof. Dr. Joachim Hornegger for giving me the opportunity to become a member of the Pattern Recognition Lab and to work in such an excellent environment. I am very grateful to my advisor Dr. Frank Forster for his support, his guidance and his valuable insights. The same is also true for Dr. Elli Angelopoulou, who accepted me in the Computer Vision group and always had advice for me. Furthermore, I would like to thank my colleagues at the Pattern Recognition Lab and at Siemens for the memorable experiences shared over the past years. Special thanks go to Philip Mewes for his help in acquiring the pig stomach datasets, which was an experience in itself. Christoph Schmalz Contents 1 Introduction 1 1.1 Motivation . 1 1.2 Organization . 2 2 Basics 5 2.1 Image Formation . 5 2.1.1 Sensors . 5 2.1.2 Color . 6 2.1.3 Light sources . 8 2.1.4 Noise . 10 2.2 Calibration . 11 2.2.1 Coordinate systems . 11 2.2.2 The pinhole camera . 12 2.2.3 Image distortion . 13 2.2.4 Calibration algorithms . 14 2.2.5 Catadioptric cameras . 16 2.2.6 Two-View Geometry . 17 2.2.7 3D Reconstruction . 18 2.3 Edge Detection and Localization . 19 2.4 Image Segmentation . 21 2.4.1 Watershed Segmentation . 22 2.5 GPU Programming . 22 3 State of the Art in Optical 3D Shape Acquisition 25 3.1 Runtime Measurement . 27 3.2 Surface Normal Methods . 28 3.3 Other methods . 28 3.4 Triangulation Methods . 29 3.4.1 Stereo and Structure-from-Motion . 29 3.4.2 Structured Light . 31 3.4.3 Error estimation for triangulation-based systems . 42 3.5 Endoscopic 3D scanning . 45 4 Design and Calibration of Single-Shot Structured Light Systems 49 4.1 General Design Goals . 49 4.2 Pattern Design . 51 4.3 System Calibration . 55 i 4.3.1 Camera Calibration with Active Targets . 55 4.3.2 Projector Calibration . 72 4.3.3 Endoscopic Camera Calibration . 73 4.3.4 Endoscopic projector calibration . 78 5 Graph-Based Pattern Decoding 85 5.1 Superpixel Representation . 86 5.1.1 Watershed Segmentation . 88 5.2 Region Adjacency Graph Setup . 91 5.2.1 Vertices . 91 5.2.2 Edges . 92 5.3 Graph Traversal . 96 5.4 Color Enhancement with Belief Propagation . 100 5.5 Edge Localization and Tracing . 107 5.6 Depth Computation . 110 6 Evaluation 113 6.1 Accuracy . 113 6.1.1 Simulated images . 113 6.1.2 Desktop reference object . 114 6.1.3 Endoscopic reference object . 118 6.1.4 Comparison with the Kinect scanner . 122 6.2 Decoding performance . 125 6.2.1 Comparison with Dynamic Programming . 125 6.3 Endoscopic measurements . 133 6.3.1 Colon Phantom . 133 6.3.2 Windpipe . 134 6.4 Runtime . 135 7 Conclusion 139 A Appendix 141 A.1 List of Publications . 141 A.2 Example Patterns . 142 A.3 Endoscopic Calibration . 144 A.4 Algorithm Parameters . 147 Bibliography 151 ii Chapter 1 Introduction 1.1 Motivation The space around us is three-dimensional. Yet, the most common representations of the world have long been only two-dimensional. There is a long tradition of paintings, and later photographs and movies. We are very good at interpreting such two- dimensional views. After all, on the retina all our visual impressions turn into a 2D pattern.
Load more

Recommended publications
  • Laser Speckle Imaging: a Quantitative Tool for Flow Analysis
    LASER SPECKLE IMAGING: A QUANTITATIVE TOOL FOR FLOW ANALYSIS A Thesis presented to the Faculty of California Polytechnic State University, San Luis Obispo In Partial Fulfillment of the Requirements for the Degree Master of Science in Biomedical Engineering by Taylor Andrew Hinsdale June 2014 © 2014 Taylor Andrew Hinsdale ALL RIGHTS RESERVED ii COMMITTEE MEMBERSHIP TITLE: Laser Speckle Imaging: A Quantitative Tool for Flow Analysis AUTHOR: Taylor Andrew Hinsdale DATE SUBMITTED: June 2104 COMMITTEE CHAIR: Lily Laiho, PhD Associate Professor of Biomedical Engineering COMMITTEE MEMBER: David Clague, PhD Associate Professor of Biomedical Engineering COMMITTEE MEMBER: John Sharpe, PhD Professor of Physics iii ABSTRACT Laser Speckle Imaging: A Quantitative Tool for Flow Analysis Taylor Andrew Hinsdale Laser speckle imaging, often referred to as laser speckle contrast analysis (LASCA), has been sought after as a quasi-real-time, full-field, flow visualization method. It has been proven to be a valid and reliable qualitative method, but there has yet to be any definitive consensus on its ability to be used as a quantitative tool. The biggest impediment to the process of quantifying speckle measurements is the introduction of additional non dynamic speckle patterns from the surroundings. The dynamic speckle pattern under investigation is often obscured by noise caused by background static speckle patterns. One proposed solution to this problem is known as dynamic laser speckle imaging (dLSI). dLSI attempts to isolate the dynamic speckle signal from the previously mentioned background and provide a consistent dynamic measurement. This paper will investigate the use of this method over a range of experimental and simulated conditions.
    [Show full text]
  • Industrial Applications of Speckle Techniques
    TRITA-IIP-02-03 ISSN-1650-1888 Industrial Applications of Speckle Techniques -Measurement of Deformation and Shape Wei An Doctoral Thesis Chair of Industrial Metrology & Optics Department of Production Engineering Stockholm 2002 Royal Institute of Technology Industrial Applications of Speckle Techniques -Measurement of Deformation and Shape Wei An Doctoral Thesis TRITA-IIP-02-03 ISSN-1650-1888 Royal Institute of Technology Department of Production Engineering Chair of Industrial Metrology & Optics 100 44 Stockholm, Sweden 2002 TRITA-IIP-02-03 ISSN-1650-1888 Copyright © Wei An Department of Production Engineering Royal Institute of Technology S-100 44 Stockholm Sweden ABSTRACT Modern industry needs quick and reliable measurement methods for measuring deformation, position, shape, roughness, etc. This thesis is mainly concerned with industrial applications of speckle metrology. Speckle metrology is an optical non-contact whole field technique that provides the means to measure; deformation and displacement, object shape, surface roughness, vibration, and dynamic events, on rough surfaces and with a sensitivity of the order of a light wavelength. In particular, the electronic speckle metrology technique combined with advanced computers, fast frame grabbers, and image processing makes it very suitable for industrial applications. The thesis consists of four main parts. The first part presents the basic principle of speckle metrology. Some formulas and theoretical analysis are reviewed. The procedure of recording electronic speckle patterns is discussed. The phase shifting and the phase unwrapping techniques are also presented in this part. The second part considers some applications of speckle metrology technique. Four types of measurements have been done during this thesis period. They correspond to deformation measurements of solder joints on electronic device boards, 3D shape measurement with light-in-flight electronic speckle pattern interferometry, continuous deformation measurement, and cutting tool monitoring.
    [Show full text]
  • Laser Speckle Photometry – Optical Sensor Systems for Condi- Tion and Process Monitoring
    MATERIALS TESTING FOR JOINING AND ADDITIVE MANUFACTURING APPLICATIONS 213 Laser speckle photometry – Optical sensor systems for condi- tion and process monitoring Lili Chen, Ulana Cikalova, Beatrice Bendjus, Laser speckle photometry (LSP) is an innovative, non-destruc- Andreas Gommlich, Shohag Roy Sudip, tive monitoring technique based on the detection and analy- Carolin Schott, Juliane Steingroewer, Dresden, sis of thermally or mechanically activated speckle dynamics Matthias Belting, Aachen, and in a non-stationary optical field. With the development of Stefan Kleszczynski, Duisburg, Germany speckle theories, it has been found that speckle patterns carry information about surface characteristics. Therefore, LSP offers a great potential for the characterization of mate- rial properties and monitoring of manufacturing processes. In contrast to the speckle interferometry method, LSP is very simple and robust. The sample is illuminated by only one la- ser beam to generate a speckle pattern on the surface. The Article Information signals obtained are directly recorded by a CCD or CMOS Correspondence Address Dr.-Ing. Beatrice Bendjus camera. By appropriate optical solutions for the beam path, Fraunhofer Institute for Ceramic typically, resolutions of less than 10 μm are reached if larger Technologies and Systems IKTS Maria-Reiche-Str. 2 areas are illuminated. LSP is definitely a contactless, quick 01109 Dresden, Germany and quality relevant material characterization and defect de- E-mail: [email protected] tection method, allowing process monitoring in many indus- Keywords trial fields. Examples from online biotechnological monitoring Laser speckle photometry, process-monitoring, defect-monitoring, build-up welding, additive and laser based manufacturing demonstrate further poten- manufacturing, biomass tials of the method for process monitoring and controlling.
    [Show full text]
  • Multiplexed Digital Holography Incorporating Speckle Correlation
    DOCTORAL T H E SIS Department of Engineering Sciences and Mathematics Division of Fluid and Experimental Mechanics Davood Khodadad Multiplexed Digital incorporating Holography Khodadad Multiplexed Speckle Correlation Davood ISSN 1402-1544 Multiplexed Digital Holography ISBN 978-91-7583-517-4 (print) ISBN 978-91-7583-518-1 (pdf) incorporatingMultiplexed SpeckleDigital Holography Correlation Luleå University of Technology 2016 incorporating Speckle Correlation Davood Khodadad Davood Khodadad Experimental Mechanics Multiplexed Digital Holography incorporating Speckle Correlation Davood Khodadad Luleå University of Technology Department of Engineering Sciences and Mathematics Division of Fluid and Experimental Mechanics February 2016 Printed by Luleå University of Technology, Graphic Production 2016 ISSN 1402-1544 ISBN 978-91-7583-517-4 (print) ISBN 978-91-7583-518-1 (pdf) Luleå 2016 www.ltu.se To you who always believe in me, my beloved parents and sisters, words could never explain how I feel about you. i Preface This work has been carried out at the Division of Fluid and Experimental Mechanics, Department of Engineering Sciences and Mathematics at Luleå University of Technology (LTU) in Sweden. The research was performed during the years 2012-2016, under the supervision of Prof. Mikael Sjödahl, LTU, Dr. Emil Hällstig, Fotonic, and Dr. Erik Olsson, LTU. First I would like to thank my supervisors Prof. Mikael Sjödahl, Dr. Emil Hällstig and Dr. Erik Olsson for their valuable support, ideas and encouragement during this work. I would also like to thank Dr. Per Gren, Dr. Henrik Lycksam and Dr. Eynas Amer for all the help in the lab. Secondly, I would like to express my gratitude to Prof.
    [Show full text]
  • Robustness of Laser Speckles As Unique Traceable Markers of Metal Components
    Article Robustness of Laser Speckles as Unique Traceable Markers of Metal Components Mikael Sjödahl * and Erik Olsson Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden; [email protected] * Correspondence: [email protected] Abstract: The traceability of manufactured components is growing in importance with the greater use of digital service solutions offered and with an increased digitalization of manufacturing logistics. In this paper, we investigate the use of image-plane laser speckles as a tool to acquire a unique code from the surface of the component and the ability to use this pattern as a secure component-specific digital fingerprint. Intensity correlation is used as a numerical identifier. Metal sheets of different materials and steel pipes are considered. It is found that laser speckles are robust against surface alterations caused by surface compression and scratching and that the correct pattern reappears from a surface contaminated by oil after cleaning. In this investigation, the detectability is close to 100% for all surfaces considered, with zero false positives. The exception is a heavily oxidized surface wiped by a cotton cloth between recordings. It is further found that the main source for lost detectability is caused by misalignment between the registration and detection geometries where a positive match is lost by a change in angle in the order of 60 mrad. Therefore, as long as the registration and detection systems, respectively, use the same optical arrangement, laser speckles have the ability to serve as unique component identifiers without having to add extra markings or a dedicated sensor to the component.
    [Show full text]
  • Customizing Speckle Intensity Statistics
    Research Article Vol. 5, No. 5 / May 2018 / Optica 595 Customizing speckle intensity statistics 1 1 2 1, NICHOLAS BENDER, HASAN YILMAZ, YARON BROMBERG, AND HUI CAO * 1Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA 2Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel *Corresponding author: [email protected] Received 9 February 2018; revised 6 April 2018; accepted 7 April 2018 (Doc. ID 322894); published 9 May 2018 Speckles commonly satisfy Rayleigh statistics. However, in many applications, non-Rayleigh speckles with customized intensity statistics are desirable. Here, we present a general method for customizing the intensity statistics of speckle patterns on a target plane. By judiciously modulating the phase front of a monochromatic laser beam, we experi- mentally generate speckle patterns with arbitrarily tailored intensity probability density functions. Relative to Rayleigh speckles, our customized speckles exhibit radically different topologies yet maintain the same spatial corre- lation length. The customized speckles are fully developed, ergodic, and stationary–with circular non-Gaussian statistics for the complex field. Propagating away from the target plane, the customized speckles revert back to Rayleigh speckles. This work provides a versatile framework for tailoring speckle patterns with varied applications in microscopy, imaging, and optical manipulation. © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement OCIS codes: (030.0030) Coherence and statistical optics; (030.6140) Speckle; (030.6600) Statistical optics. https://doi.org/10.1364/OPTICA.5.000595 1. INTRODUCTION the speckle pattern could possess an intensity PDF with a tail Speckle formation is a phenomenon inherent to both classical and decaying either slower or faster than a negative-exponential func- quantum waves.
    [Show full text]
  • Simple and Versatile Heterodyne Whole-Field Interferometer for Phase Optics Characterization D
    Simple and versatile heterodyne whole-field interferometer for phase optics characterization D. M. Silva, E. A. Barbosa, and N. U. Wetter Citation: Rev. Sci. Instrum. 83, 103103 (2012); doi: 10.1063/1.4757396 View online: http://dx.doi.org/10.1063/1.4757396 View Table of Contents: http://rsi.aip.org/resource/1/RSINAK/v83/i10 Published by the American Institute of Physics. Related Articles Continuously tunable optical multidimensional Fourier-transform spectrometer Rev. Sci. Instrum. 84, 023107 (2013) The frequency stabilization method of laser feedback interferometer based on external cavity modulation Rev. Sci. Instrum. 84, 025108 (2013) Efficient end-fire coupling of surface plasmons on flat metal surfaces for improved plasmonic Mach-Zehnder interferometer J. Appl. Phys. 113, 053101 (2013) Automation of an “Aculight” continuous-wave optical parametric oscillator Rev. Sci. Instrum. 84, 013102 (2013) Two-path solid-state interferometry using ultra-subwavelength two-dimensional plasmonic waves Appl. Phys. Lett. 102, 021104 (2013) Additional information on Rev. Sci. Instrum. Journal Homepage: http://rsi.aip.org Journal Information: http://rsi.aip.org/about/about_the_journal Top downloads: http://rsi.aip.org/features/most_downloaded Information for Authors: http://rsi.aip.org/authors Downloaded 14 Mar 2013 to 143.107.255.190. Redistribution subject to AIP license or copyright; see http://rsi.aip.org/about/rights_and_permissions REVIEW OF SCIENTIFIC INSTRUMENTS 83, 103103 (2012) Simple and versatile heterodyne whole-field interferometer for
    [Show full text]
  • Universal Sensitivity of Speckle Intensity Correlations to Wavefront Change in Light Diffusers
    Universal sensitivity of speckle intensity correlations to wavefront change in light diffusers KyungDuk Kim,1 HyeonSeung Yu,1 KyeoReh Lee,1 and YongKeun Park1* 1Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea Here, we present a concept based on the realization that a complex medium can be used as a simple interferometer. Changes in the wavefront of an incident coherent beam can be retrieved by analyzing changes in speckle patterns when the beam passes through a light diffuser. We demonstrate that the spatial intensity correlations of the speckle patterns are independent of the light diffusers, and are solely determined by the phase changes of an incident beam. With numerical simulations using the random matrix theory, and an experimental pressure-driven wavefront- deforming setup using a microfluidic channel, we theoretically and experimentally confirm the universal sensitivity of speckle intensity correlations, which is attributed to the conservation of optical field correlation despite multiple light scattering. This work demonstrates that a complex media is a simple interferometer, and presents opportunities to replace complicated reference-beam-assisted interferometers with a simple and compact scattering layer in various applications in metrology, analytical chemistry, and biomedicine. I. INTRODUCTION Speckle is a granular pattern that appears when highly coherent light is scattered by a random structure [1]. In contrast to efforts to suppress speckle to improve imaging quality [2-5], there have also been approaches to exploit speckle patterns as a means of gathering physical information about a target. This field of research, known as speckle metrology, enables the measurement of various physical quantities such as vibration [6], roughness [7], and velocity [8].
    [Show full text]
  • Application of Electronic Speckle Pattern Interferometry Method for Simultaneous Measurement of Young’S Modulus and the Poisson’S Ratio of Metals †
    Proceedings Application of Electronic Speckle Pattern Interferometry Method for Simultaneous Measurement of Young’s Modulus and the Poisson’s Ratio of Metals † Alexandre Michtchenko *, Juan Benito Pascual Francisco and Omar Barragán Pérez Instituto Politécnico Nacional, Seccion de Estudios de Posgrado e Investigación, ESIME-ZAC, México 07738, Mexico; [email protected] (J.B.P.F.); [email protected] (O.B.P.) * Correspondence: [email protected]; Tel.: +52-5512-9773-26 † Presented at the 18th International Conference on Experimental Mechanics (ICEM18), Brussels, Belgium, 1–5 July 2018. Published: 28 June 2018 Abstract: In this paper, mechanical experiments with a low-cost interferometry set-up are presented. The set-up is suitable for an undergraduate laboratory where optical equipment is absent. The arrangement consists of two planes of illumination, allowing the measurement of the two perpendicular in-plane displacement directions. An axial load was applied to three different metals, and the longitudinal and transversal displacements were measured sequentially. A digital camera was used to acquire the images of the different states of the load of the illuminated area. A personal computer was used to perform the digital subtraction of the images to obtain the fringe correlations, which are needed to calculate the displacements. Finally, Young’s modulus and Poisson’s ratio of the metals were calculated using the displacement data. Keywords: electronic speckle pattern interferometry; Poisson’s ratio; Young’s modulus 1. Introduction Electronic Speckle Pattern Interferometry (ESPI) is a technique for full-field displacement measurement and has been well accepted in experimental mechanics field [1,2]. Sophisticated equipment has been developed for this purpose, and usually employ relative expensive items such as CCD camera, frame grabber, mirror mounts, PZT, etc.
    [Show full text]
  • Speckling in Diffraction Patterns and Optical Images Formed with the Laser
    viii SPECKLING IN DIFFRACTION PATTERNS AND OPTICAL IMAGES FORMED WITH THE LASER H.H. Hopkins H. Tiziani The University, Reading E.T.H., Zurich Abstract Elementary physical considerations are used to show that the waves scattered from an optically rough surface have not only random phases but also random real amplitudes. The same simple physical model serves to establish the main features of speckling in diffraction patterns, namely (i) that the smallest size of detail in any azimuth is determined by the formula O.5A/e, where 0 is the angular diameter of the object in that azimuth, (ii) that the scale of the speckling is predominantly of this order of size, and (iii) that speckling is expected to be of high contrast. This last conclusion is easily derived from the randomness of the real amplitudes of the scattered waves. The result (ii) is obtained by finding the autocorrelation function of the diffracted intensity distribution, following Goldfischer (1965). In the formation of the image of a rough object using coherent light, the entrance pupil is illuminated by a speckled diffraction pattern. This random illumination then appears in the exit pupil, so that the speckling in the image is determined by considering the exit pupil to act as a rough object. The order of size of speckling in the image is thus determined by the formula O. S6 /A, where 6 is now the total convergence angle of the image-forming pencil. 0 0 (1) Physical Considerations : The Envelope of the Diffraction Pattern and the Minimum Size of Speckle We silall consider first the factors wbich determine the form of the envelope of the intensity in the diffraction pattern.
    [Show full text]
  • Holographic and Speckle Methods - A
    EXPERIMENTAL MECHANICS - Holographic and Speckle Methods - A. Albertazzi G. Jr, M. R. Viotti HOLOGRAPHIC AND SPECKLE METHODS A. Albertazzi G. Jr Department of Mechanical Engineering, Universidade Federal de Santa Catarina, Brazil M. R. Viotti Optical Metrology Division, Photonita Ltda, Brazil Keywords: Experimental mechanics, optical metrology, holography, holographic interferometry, digital holography, speckle, speckle correlation, speckle interferometry, DSPI, ESPI. Contents 1. Holographic Methods 1.1. Light Waves 1.1.1. Wave mathematics 1.1.2. Interference 1.1.3. Interference Fringes 1.1.4. Phase Extraction 1.2. Film Holography 1.2.1. Hologram Recording 1.2.2. Hologram Reconstruction 1.3. Holographic Interferometry 1.3.1. Double Exposure Holographic Interferometry 1.3.2. Real Time Holographic Interferometry 1.3.3. Time Average Holographic Interferometry 1.3.4. Interpretation of Interference Fringes 1.3.5. Special Applications 1.4. Digital Holography 1.4.1. Basic Principle 1.4.2. Digital holographic interferometry 2. Speckle Methods 2.1 The speckle effect 2.1.1. Objective speckle 2.1.2. Subjective speckle 2.2 Speckle Photography 2.3. Digital Speckle Interferometry 2.3.1. Basic Principle 2.3.2. Interpretation of Interference Fringes 2.3.3. Special Configurations 2.3.4. Vibration measurement 2.4. Shearography 2.4.1. Basic principle 2.4.2. Formation and Interpretation of Interference Fringes 2.4.3. Applications Glossary ©Encyclopedia of Life Support Systems(EOLSS) EXPERIMENTAL MECHANICS - Holographic and Speckle Methods - A. Albertazzi G. Jr, M. R. Viotti Bibliography Biographical Sketches Summary Two important full filed optical techniques widely used in experimental mechanic applications are presented in this topic: holography and speckle methods.
    [Show full text]
  • Speckle Mechanism in Holographic Optical
    SPECKLE MECHANISM IN HOLOGRAPHIC OPTICAL COHERENCE IMAGING _______________________________________________________________________________ A Dissertation Presented to The Faculty of the Graduate School University of Missouri _____________________________________________________________ In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy _____________________________________________________________ By HAIBO LIN Dr. Ping Yu, Dissertation Supervisor May 2009 The undersigned, appointed by the Dean of the Graduate School, have examined the dissertation entitled: SPECKLE MECHANISM IN HOLOGRAPHIC OPTICAL COHERENCE IMAGING presented by Haibo Lin a candidate for the degree of Doctor of Philosophy and hereby certify that in their opinion, it is worthy of acceptance. ____________________________________ Dr. Ping Yu ____________________________________ Dr. Liqun (Andrew) Gu ____________________________________ Dr. Meera Chandrasekhar ____________________________________ Dr. Suchismita Guha ____________________________________ Dr. H. R. Chandrasekhar To my parents: Aimei He and Zhimin Lin and my wife: Huifang Zhai ACKNOWLEDGEMENTS I have been fortunate to work with professors who have been encouraging and supportive of my endeavors during my Ph.D. study. I would like to specially thank my thesis advisor, Prof. Ping Yu who has been invaluable in his constant support, continuous motivation and inspiration, and in allowing me to work in an environment with the freedom to explore different avenues of research. In giving me the opportunity to attend conferences, he has contributed immeasurably to my personal and professional growth. I would like to thank Prof. Lixin Ma and Dr. Sunder Balasubramanian for their help and support since the beginning of my research. Thanks to Prof. David Nolte, Dr. Kwan Jeong and Yihong Liu from Purdue University for generously providing the quantum well device and training for device fabrication.
    [Show full text]