Download or read book Improving the Performance of Optical Feedback Self mixing Interferometry for Vibration Measurement written by Yi Zhang and published by . This book was released on 2006 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Self mixing Interferometry for Metrology Applications written by Reza Atashkhooei and published by . This book was released on 2014 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the laser based techniques proposed for metrology applications, classical interferometers offer the highest precision measurements. However, the cost of some of the elements involved and the number of optical components used in the setup complicates using them in several industrial applications. Apart from cost, the complexities due to optical alignment and the required quality of the environmental conditions can be quite restrictive for those systems. Within the category of optical interferometers, optical feedback interferometry (OFI), also called self-mixing interferometry (SMI) has the potential to overcome some of the complexities of classical interferometry. It is compact in size, cost effective, robust, self-aligned, and it doesn't require a large number of optical components in the experimental configuration. In OFI, a portion of the emitted laser beam re-enters to the laser cavity after backreflection from the target, causing the wavelength of the laser to change, modifying the power spectrum and consequently the emitted output power, which can be detected for measurement purposes. Thus, the laser operates simultaneously as the light source, the light detector, and as the ultra-sensitive coherent sensor for optical path changes. The present PhD pursued improving the performance of OFI-based sensors using a novel and compact optical system. A solution using an adaptive optical element in the form of a voltage programmable liquid lens was proposed for automated focus adjustments. The amount of backreflected light re-entering the laser cavity could be controlled, and the laser feedback level was adjusted to the best condition in different situations, enabling the power signal to be adjusted to the best possible conditions for measurement. Feedback control enabled the proposal of a novel solution called differential OFI, which improved the measurement resolution down to the nanometre order, even if the displacements were below half-wavelength of the laser, for first time in OFI sensors. Another relevant part of the PhD was devoted to the analysis of speckle-affected optical power signals in feedback interferometers. Speckle effect appears when the displacements of the target are large, and introduces an undesired modulation of the amplitude of the signal. After an analysis of the speckle-affected signal and the main factors contributing to it, two novel solutions were proposed for the control of speckle noise. The adaptive optical head developed previously was used in a real time setup to control the presence of speckle effect, by tracking the signal to noise ratio of the emitted power, and modifying the spot size on the target when required using a feedback loop. Besides, a sensor diversity solution was proposed to enable enhancements in signal detection in fast targets, when real time control could not be applied. Finally, two industrial applications of the technique with the presence of different levels of speckle noise have been presented. A complete measurement methodology for the control of motor shaft runout in permanent magnet electrical motors, enabling complete monitoring of the displacement of the shaft has been developed and implemented in practice. Results here are validated with those obtained using a commercial laser Doppler vibrometer, an equipment with a much higher cost. A second application in the monitoring the displacement of polymer-reinforced beams used in civil engineering under dynamic loading was also demonstrated. Results here are validated using a conventional contact probe (a Linear Vertical Differential Transducer, LVDT). Both applications show that with controlled speckle features OFI performs adequately in industrial environments as a non-contact proximity probe with resolution limited by the constraints defined by the setup.
Download or read book Self mixing Interferometry for Absolute Distance Measurement written by Mengkoung Veng (docteur en photonique).) and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-mixing Interferometry has been studied extensively in the last five decades in various sensing applications. Sensors under the SMI technique have the laser diode as the light source, the interferometer, and the detector. The light from the laser diode propagates towards a distant target where it is partially reflected or back-scattered before being re-injected into the active cavity of the laser. When the laser diode experiences the external optical feedback, the reflected light imprinted with information from the distant target or from the external cavity medium induces perturbation to the operating parameters of the laser. For SMI measurement sensors such as harmonic motion and absolute distance applications, the fringe counting method is basically used to determine the target's displacement and distance respectively. Two different approaches to modelling the SMI phenomenon have been developed: the three-mirror cavity and the perturbation of the rate equation. The single equation that describes the phase condition imposed by the optical feedback is usually referred to as the excess phase equation. One of the most important and most useful parameters in the excess phase equation is the feedback parameter C as it can be used to qualitatively categorize the regime of the laser under optical feedback. When the feedback level C 1, the laser behaviour is stable. On the other hand, when the feedback level C 1, more complex phenomena are observed such as hysteresis effect, presence of multiple emission frequencies (including the unstable frequencies), apparent splitting of the emission line due to mode hopping and fringe disappearance phenomenon. The fringes disappearance phenomenon in the self-mixing interferometry occurs whenever the external round-trip phase at free-running state is modulated by either external modulation such as external cavity length changes or internal modulation when the laser injection current is modulated with a high back-scattered light power. This phenomenon has been observed by many authors for harmonic motion or vibration application and more recently in the case of the absolute distance measurement scheme when the laser injection current is modulated in the triangle waveform. This phenomenon is highly dependent on the feedback parameter C and it is described in detail based on the coupled cavity model. The primary cause for fringes disappearance is demonstrated to be the expansion of the excess phase equation stable solutions range with the increment of the parameter C, thus reducing the number of stable solutions for a given phase stimulus. This new approach in the modelling of the fringe disappearance phenomenon allows determination of the C values for which a pair of fringes are expected to disappear and as a consequence correlates the number of missing fringes to the value of C. This approach is validated both by a behavioural model of the laser under optical feedback and by a series of measurements in the SMI absolute distance configuration.
Download or read book Implementation of Differential Self mixing Interferometry Systems for the Detection of Nanometric Vibrations written by Francisco Javier Azcona Guerrero and published by . This book was released on 2018 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Thesis, we explore Self-mixing interferometry (SMI ), a method capable of producing high resolution optical path related measurements in a simple, compact and cost-effective way. Even with a notably less complex setup than traditional interferometric methods, SMI can produce measurements with a resolution well below the micrometric scale (N'2) which is sufficient for most industrial applications. The SMI effect is produced when a small part of the laser power impacting a target is back-scattered and re-injected into the laser cavity. As a result, the phase and amplitude of the laser wave is modified generating a signature beat, which can be "easily" related to different optical path-related dynamics. The main advantage of this method in relation to other interferometric methods is the simple setup consisting mainly of a single mode laser diode (LO) equipped with a simple electronic system readout a simple optical system may be used to collimate/focus the beam allowing measurements at larger distances. Because of the small amount of reflected optical power required to allow the effect, the technique can produce high resolution measurements even with diffusive targets. While the SMI method has been largely studied in the last three decades, there are still several topics worth the development of further research. One of those topics, how to increase the resolution on displacement measurements, is one of the main topics covered in this work. Classical SMI methods allow the reconstruction of displacement measurement with a resolution of N'2. The use of special processing algorithms can push further this limit reaching values in the order of e.g. N32. In this work, we propose a method to increase even further this limit reach values better than N100.The idea discussed, differential self-mixing interferometry (OSMI) proposes the use of a reference modulation (mechanical or electrical) to be used as a reference for the measurement. Simulated results have shown that under ideal conditions, it may be possible to reach resolutions in the order of N1000. In practice, however, this limit is much smaller (N100) because of LO dynamics, and different practical limitations present in the amplification and readout electronics. Experiments and measurements are presented along the second chapter of this work to present proof of the proposed method. After exploring the basics of OSMI, possible applications for classic SMI and DSMI were pursued. The obtained results are presented in the following sections. First, a review on potential biomedical measurements using SMI is discussed. The obtained results suggest that it is possible to obtain some key values related to biomedical constants (e.g. P.PW) using a displacement SMI measurement. The method, however, may not be reliable enough especially on long time measurements. Moreover, the use of certain wavelengths must be avoided during long exposures as they may prove harmful to the soft tissue due to the requirements of a small laser spot. lt is observed that SNR may lead to difficulties during the signal processing stage which may impact the results of the reconstructed signal. Next, the DSMI method was tested in an AFM-like cantilever system. The results suggest that is possible to follow the motion of a micrometric size cantilever oscillating at low frequencies with a high resolution. Higher frequencies may be achieved by using an electronic reference modulation configuration. The proposed system was able to detect some artefacts on the motion which maybe attributed to possible deflections on the cantilever surface. Possible enhancements to the method are suggested for any researcher who wants to expand the topic.
Download or read book Semiconductor Lasers written by Junji Ohtsubo and published by Springer. This book was released on 2017-05-03 with total page 679 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in semiconductor lasers are discussed, but also for example the method of self-mixing interferometry in quantum-cascade lasers, which is indispensable in practical applications. Further, this edition covers chaos synchronization between two lasers and the application to secure optical communications. Another new topic is the consistency and synchronization property of many coupled semiconductor lasers in connection with the analogy of the dynamics between synaptic neurons and chaotic semiconductor lasers, which are compatible nonlinear dynamic elements. In particular, zero-lag synchronization between distant neurons plays a crucial role for information processing in the brain. Lastly, the book presents an application of the consistency and synchronization property in chaotic semiconductor lasers, namely a type of neuro-inspired information processing referred to as reservoir computing.
Download or read book Precision Dimensional Measurements written by Kuang-Chao Fan and published by MDPI. This book was released on 2019-10-21 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection represents successful invited submissions from the papers presented at the 8th Annual Conference of Energy Economics and Management held in Beijing, China, 22–24 September 2017. With over 500 participants, the conference was co-hosted by the Management Science Department of National Natural Science Foundation of China, the Chinese Society of Energy Economics and Management, and Renmin University of China on the subject area of “Energy Transition of China: Opportunities and Challenges”. The major strategies to transform the energy system of China to a sustainable model include energy/economic structure adjustment, resource conservation, and technology innovation. Accordingly, the conference and its associated publications encourage research to address the major issues faced in supporting the energy transition of China. Papers published in this collection cover the broad spectrum of energy economics issues, including building energy efficiency, industrial energy demand, public policies to promote new energy technologies, power system control technology, emission reduction policies in energy-intensive industries, emission measurements of cities, energy price movement, and the impact of new energy vehicle.
Download or read book Analysis and Pre processing of Signals Observed in Optical Feedback Self mixing Interferometry written by Xiaochun Zhang and published by . This book was released on 2008 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electro Optical Instrumentation written by Silvano Donati and published by Pearson Education. This book was released on 2004-04-09 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complete, practical sourcebook for laser sensing and measurement This is a systematic, up-to-date guide to laser instrumentation for sensing and measurement in contemporary scientific, industrial, automotive and avionics applications. Dr. Silvano Donati presents clear design rules and useful hints for practical implementation of a wide variety of laser instruments. For each type of instrument, the author outlines basic principles, physical limitations, reasonable performance expectations, optical design issues, and electronic signal handling--illustrated with block schemes. Coverage includes: Interferometers for sub-micrometer displacement measurements Nanometer vibrometers and structural integrity testing Doppler velocimeters for anemometry of fluids Range finders and anti-collision systems Non-contact wire-diameter and particle-diameter sizing Alignment and level meter apparatuses Ring laser and optical fiber gyroscopes Optical fiber sensors Thorough and accessible, Electro-Optical Instrumentation offers balanced coverage of both optical and electronic issues and challenges. It will give working electronic engineers and scientists the knowledge they need to design virtually any electro-optical instrumentation system. PRENTICE HALL Upper Saddle River, NJ 07458 www.phptr.com
Download or read book Implementation of a High Resolution Optical Feedback Interferometer for Microfluidics Applications written by Raul da Costa Moreira and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent progress of interferometric sensors based on the optical feedback in a laser diode have demonstrated possibility for measurement of flow rates and flow-profiles at the micro-scale. That type of compact and embedded sensors is very promising for a research and industrial field -microfluidics - that is a growing domain of activities, at the frontiers of the physics, the chemical science, the biology and the biomedical. However, the acquisition of flow rate or local velocity at high resolution remains a very challenging issue, and the sensors that have been proposed so far did not have been giving sufficient information on the nature of the particles flowing. The present thesis is driven to the implementation, validation and evaluation of the sensing performances of the optical feedback interferometry technology in both chemical and biomedical fields of applications. The elaboration of a new generation of sensors that will provide both a high spatial resolution for 2D Doppler imaging is presented, as well as a methodology that gives further information on the flowing particles concentration and/or dimensions. Then, a new embedded optical feedback interferometry imager for flowmetry has been realized using a 2-axis beamsteering mirror mounted on Micro-Electro-Mechanical Systems (MEMS) thus taking the full advantage of the compactness offered by the optical feedback interferometry sensing scheme. While previous works on optical feedback interferometry flowmetry have been limited to high particle densities fluids in single or multiple scattering regimes, we present also a sensing technique based on the optical feedback interferometry scheme in a laser diode that enables single particle detection at micro and nanoscales through the Doppler-Fizeau effect. Thanks to the proposed signal processing, this sensing technique can detect the presence of single spherical polystyrene micro/nanospheres seeded in watery suspensions, and measure their flow velocity, even when their diameter is below half the laser wavelength. It discriminates particle by their diameter up to a ratio of 5 between large and small ones while most of the technologies for particle characterization is bulk and requires manipulation of the fluid with small volume handling, precise flow and concentration control. Altogether, the results presented in this thesis realize a major improvement for the use of optical feedback interferometry in the chemical engineering or biomedical applications involving micro-scale flows.
Download or read book Optimization of Velocity and Displacement Measurement with Optical Encoder and Laser Self mixing Interferometry written by Hui Sun and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modern Development Paths of Agricultural Production written by Volodymyr Nadykto and published by Springer. This book was released on 2019-07-02 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest trends and challenges in the development of general engineering and mechanical engineering in the agriculture and horticulture sectors.
Download or read book Handbook of Experimental Structural Dynamics written by Randall Allemang and published by Springer Nature. This book was released on 2022-06-30 with total page 1426 pages. Available in PDF, EPUB and Kindle. Book excerpt: The SEM Handbook of Experimental Structural Dynamics stands as a comprehensive overview and reference for its subject, applicable to workers in research, product design and manufacture, and practice. The Handbook is devoted primarily to the areas of structural mechanics served by the Society for Experimental Mechanics IMAC community, such as modal analysis, rotating machinery, structural health monitoring, shock and vibration, sensors and instrumentation, aeroelasticity, ground testing, finite element techniques, model updating, sensitivity analysis, verification and validation, experimental dynamics sub-structuring, quantification of margin and uncertainty, and testing of civil infrastructure. Chapters offer comprehensive, detailed coverage of decades of scientific and technologic advance and all demonstrate an experimental perspective. Several sections specifically discuss the various types of experimental testing and common practices utilized in the automotive, aerospace, and civil structures industries. · History of Experimental Structural Mechanics · DIC Methods - Dynamic Photogrammetry · LDV Methods · Applied Digital Signal Processing · Introduction to Spectral - Basic Measurements · Structural Measurements - FRF · Random and Shock Testing · Rotating System Analysis Methods · Sensors Signal Conditioning Instrumentation · Design of Modal Tests · Experimental Modal Methods · Experimental Modal Parameter Evaluation · Operating Modal Analysis Methods · Analytical Numerical Substructuring · Finite Element Model Correlation · Model Updating · Damping of Materials and Structures · Model Calibration and Validation in Structures · Uncertainty Quantification: UQ, QMU and Statistics · Nonlinear System Analysis Methods (Experimental) · Structural Health Monitoring and Damage Detection · Experimental Substructure Modeling · Modal Modeling · Response (Impedance) Modeling · Nonlinear Normal Mode Analysis Techniques (Analytical) · Modal Modeling with Nonlinear Connection Elements (Analytical) · Acoustics of Structural Systems (VibroAcoustics) · Automotive Structural Testing · Civil Structural Testing · Aerospace Perspective for Modeling and Validation · Sports Equipment Testing · Applied Math for Experimental Structural Mechanics Contributions present important theory behind relevant experimental methods as well as application and technology. Topical authors emphasize and dissect proven methods and offer detail beyond a simple review of the literature. Additionally, chapters cover practical needs of scientists and engineers who are new to the field. In most cases, neither the pertinent theory nor, in particular, the practical issues have been presented formally in current academic textbooks. Each chapter in the Handbook represents a ’must read’ for someone new to the subject or for someone returning to the field after an absence. Reference lists in each chapter consist of the seminal papers in the literature. This Handbook stands in parallel to the SEM Handbook of Experimental Solid Mechanics, where this Handbook focuses on experimental dynamics of structures at a macro-scale often involving multiple components and materials where the SEM Handbook of Experimental Solid Mechanics focuses on experimental mechanics of materials at a nano-scale and/or micro-scale.
Download or read book An Introduction to Self mixing Interferometry with an Application to Vibrometry written by Matthew L. O'Donnell and published by . This book was released on 2008 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structural Health Monitoring of Civil Infrastructure Systems written by Vistasp M. Karbhari and published by Elsevier. This book was released on 2009-08-25 with total page 553 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural health monitoring is an extremely important methodology in evaluating the 'health' of a structure by assessing the level of deterioration and remaining service life of civil infrastructure systems. This book reviews key developments in research, technologies and applications in this area of civil engineering. It discusses ways of obtaining and analysing data, sensor technologies and methods of sensing changes in structural performance characteristics. It also discusses data transmission and the application of both individual technologies and entire systems to bridges and buildings.With its distinguished editors and international team of contributors, Structural health monitoring of civil infrastructure systems is a valuable reference for students in civil and structural engineering programs as well as those studying sensors, data analysis and transmission at universities. It will also be an important source for practicing civil engineers and designers, engineers and researchers developing sensors, network systems and methods of data transmission and analysis, policy makers, inspectors and those responsible for the safety and service life of civil infrastructure. - Reviews key developments in research, technologies and applications - Discusses systems used to obtain and analyse data and sensor technologies - Assesses methods of sensing changes in structural performance
Download or read book Laser Radar written by National Research Council and published by National Academies Press. This book was released on 2014-03-14 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: In today's world, the range of technologies with the potential to threaten the security of U.S. military forces is extremely broad. These include developments in explosive materials, sensors, control systems, robotics, satellite systems, and computing power, to name just a few. Such technologies have not only enhanced the capabilities of U.S. military forces, but also offer enhanced offensive capabilities to potential adversaries - either directly through the development of more sophisticated weapons, or more indirectly through opportunities for interrupting the function of defensive U.S. military systems. Passive and active electro-optical (EO) sensing technologies are prime examples. Laser Radar considers the potential of active EO technologies to create surprise; i.e., systems that use a source of visible or infrared light to interrogate a target in combination with sensitive detectors and processors to analyze the returned light. The addition of an interrogating light source to the system adds rich new phenomenologies that enable new capabilities to be explored. This report evaluates the fundamental, physical limits to active EO sensor technologies with potential military utility; identifies key technologies that may help overcome the impediments within a 5-10 year timeframe; considers the pros and cons of implementing each existing or emerging technology; and evaluates the potential uses of active EO sensing technologies, including 3D mapping and multi-discriminate laser radar technologies.
Download or read book Unlocking Dynamical Diversity written by Deborah M. Kane and published by John Wiley & Sons. This book was released on 2005-11-01 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applications of semiconductor lasers with optical feedback systems are driving rapid developments in theoretical and experimental research. The very broad wavelength-gain-bandwidth of semiconductor lasers combined with frequency-filtered, strong optical feedback create the tunable, single frequency laser systems utilised in telecommunications, environmental sensing, measurement and control. Those with weak to moderate optical feedback lead to the chaotic semiconductor lasers of private communication. This resource illustrates the diversity of dynamic laser states and the technological applications thereof, presenting a timely synthesis of current findings, and providing the roadmap for exploiting their future potential. * Provides theory-based explanations underpinned by a vast range of experimental studies on optical feedback, including conventional, phase conjugate and frequency- filtered feedback in standard, commercial and single-stripe semiconductor lasers * Includes the classic Lang-Kobayashi equation model, through to more recent theory, with new developments in techniques for solving delay differential equations and bifurcation analysis * Explores developments in self-mixing interferometry to produce sub-nanometre sensitivity in path-length measurements * Reviews tunable single frequency semiconductor lasers and systems and their diverse range of applications in sensing and optical communications * Emphasises the importance of synchronised chaotic semiconductor lasers using optical feedback and private communications systems Unlocking Dynamical Diversity illustrates all theory using real world examples gleaned from international cutting-edge research. Such an approach appeals to industry professionals working in semiconductor lasers, laser physics and laser applications and is essential reading for researchers and postgraduates in these fields.
Download or read book Optical Measurements written by Franz Mayinger and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing possibilities of computer-aided data processing have caused a new revival of optical techniques in many areas of mechanical and chemical en gineering. Optical methods have a long tradition in heat and mass transfer and in fluid dynamics. Global experimental information is not sufficient for developing constitution equations to describe complicated phenomena in fluid dynamics or in transfer processes by a computer program . Furthermore, a detailed insight with high local and temporal resolution into the thermo-and fluiddynamic situations is necessary. Sets of equations for computer program in thermo dynamics and fluid dynamics usually consist of two types of formulations: a first one derived from the conservation laws for mass, energy and momentum, and a second one mathematically modelling transport processes like laminar or turbulent diffusion. For reliably predicting the heat transfer, for example, the velocity and temperature field in the boundary layer must be known, or a physically realistic and widely valid correlation describing the turbulence must be avail able. For a better understanding of combustion processes it is necessary to know the local concentration and temperature just ahead of the flame and in the ignition zone.
