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Dissertations / Theses on the topic 'Laser metrology'
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Ortiz, Julio Enrique. "New millennium interferometer laser metrology testbed." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42639.
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Hines, Braden E. (Braden Eric). "Laser metrology system for stellar interferometry." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14769.
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Hospodar, Edward J. "A laser metrology system for precision pointing." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FHospodar.pdf.
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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2003.Thesis advisor(s): Brij N. Agrawal, Hong-Jen Chen. Includes bibliographical references (p. 63). Also available online.
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Dunmeyer, David Richard 1978. "Laser speckle modeling for three-dimensional metrology and LADAR." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16763.
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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 103-111).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
In this thesis, I developed three-dimensional laser-speckle models to help in the development process of three-dimensional optical-metrology imaging systems. These models were developed to aid in the proof of concept for various three-dimensional metrology techniques. These models were then compared to real-world imaging systems, developed by both the author and other staff at the MIT Lincoln Laboratory, to determine their ability to accurately model said imaging systems. I also looked at the laser speckle statistics associated with mid-field systems in an exo-atmospheric environment as they relate to LADAR.
by David Richard Dunmeyer.
M.Eng.and S.B.
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Oram, Richard Joseph. "An investigation of the frequency stability and passive ultra low thermal expansion glass ceramic optical cavities." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304656.
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Barwood, Geoffrey P. "Frequency stabilised laser diodes and their use in length metrology." Thesis, University of Kent, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314498.
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Dacasa, Pereira Hugo. "Spatial and temporal metrology of coherent ultrashort pulses inthe extreme-ultraviolet domain." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX041/document.
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Les impulsions ultra-brèves de rayonnement ultraviolet extrême (UVX) ont un grand champ d’application dans les domaines tels que le diagnostic de plasmas, la spectroscopie ou l’étude de la dynamique ultrarapide dans les atomes et les molécules.Aujourd’hui, il existe trois sources délivrant ce genre d’impulsions. Les harmoniques d’ordre élevé (HHG, en anglais) générés dans les gaz rares ou sur les solides peuvent fournir des impulsions attosecondes. Cependant, leur énergie, le plus souvent de l’ordre du nanojoule, limite les applications. L’amplification des impulsions harmoniques dans les plasmas créés par laser (SXRL, en anglais) a démontré pouvoir fournir des énergies de plusieurs dizaines de microjoules. Des énergies plus élevées peuvent être obtenues avec les lasers à électrons libres (LEL) UVX injectés, mais ce sont des Très Grandes Infrastructures ayant un accès limité.Ces dernières années, des progrès significatifs ont été réalisé avec chacune des ces sources, avec pour objectif la génération d’impulsions plus brèves. Il est devenu nécessaire de développer des nouvelles techniques de métrologie temporelle des impulsions UVX ultra-brèves. De plus, beaucoup d’expériences, comme ceux impliquant des phénomènes non-linéaires, nécessitent de hautes intensités UVX. La focalisation efficace des impulsions de faibles énergies peut significativement augmenter le domaine d’application. De bons fronts d’onde sont nécessaires pour focaliser les impulsions UVX à haute intensité, et les optiques doivent aussi être de bonne qualité et alignées avec précision.Dans cette thèse, les propriétés spatiales des harmoniques d’ordre élevé ont été extensivement étudiées grâce à un senseur de front d’onde UVX. Cet appareil couplé à une source HHG a démontré être utile pour la caractérisation de table et à la longueur d’onde ainsi que pour l’optimisation de systèmes optiques UVX.Le problème de la mise en place de la complète caractérisation temporelle d’impulsions UVX est aussi discuté en détail, et deux nouveaux schémas pour la reconstruction d’impulsions de LEL injectés et de lasers X à plasma sont présentés. Finalement, la première implantation d’un système d’amplification à dérive de fréquence (CPA, en anglais) sur un LEL UVX est présentée et son implantation pour les lasers X à plasmas est aussi discutéeUltrashort pulses of extreme-ultraviolet (XUV) radiation have a wide range of applications in fields such as plasma probing, spectroscopy, or the study of ultrafast dynamics in atoms and molecules.Nowadays, there are three main sources of such pulses. High-order harmonic generation (HHG) in rare gases or solid surfaces is able to provide attosecond pulses. However, their limited energy, of the order of nanojoules, limits its number of applications. The amplification of high-harmonic pulses in laser-driven plasmas (SXRL) has been demonstrated to provide energies of tens of microjules. Higher pulse energies can be obtained from seeded XUV free-electron lasers (FELs), large-scale facilities with more limited accessibility.In recent years, significant progress has been made with each of these sources towards the generation of shorter pulses. It is thus necessary to develop new techniques for full temporal metrology of ultrashort XUV pulses. Additionally, many experiments, such as those involving nonlinear phenomena, require high XUV intensities. Efficient focusing of low-energy pulses can significantly increase their range of application. Good wavefronts are required in order to focus XUV pulses to high intensities, and the optics must be of high quality and precisely aligned.In this thesis, the spatial properties of high-harmonic pulses are extensively explored thanks to the use of an XUV Hartmann wavefront sensor. This device is also proven here to be useful for tabletop, at-wavelength characterization and optimization of XUV optical systems with HHG sources.The problem of performing full temporal characterization of XUV pulses is also discussed in detail, and two new schemes for complete pulse reconstruction for seeded XUV FELs and seeded SXRLs are presented. Finally, the first implementation of chirped pulse amplification (CPA) in a seeded XUV FEL is reported, and its implementation in seeded SXRLs is discussed as well
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Deprez, Maxime. "Moyen de métrologie pour la conception et l’évaluation de chaines lasers hyper intenses utilisant la recombinaison cohérente de lasers élémentaires." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS241/document.
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La nécessité de la montée en puissance, crête et moyenne, des chaines lasers hyper intenses a fait émerger un nouveau type d'architecture. Le principe consiste à combiner de manière cohérente un grand nombre de lasers élémentaires les plus simples et robustes possible. La difficulté de la montée en puissance est donc reportée essentiellement sur le système de recombinaison. Plusieurs laboratoires à travers le monde ont ainsi décidé de s'impliquer dans cette voie. S'il existe des concepts variés pour la boucle d'asservissement, il n'y a pas pour l'instant, à notre connaissance, de développement d'un moyen de métrologie absolue de la qualité du front d'onde final, et donc de la recombinaison. Or celui-ci est fondamental pour deux moments particuliers de la conception de ces nouvelles architectures.Dans un premier temps, il est nécessaire de connaître la nature, l'amplitude et la fréquence des défauts de phase en boucle ouverte afin de bien spécifier l'architecture de la tête optique et le système de contrôle/commande. Puis, lorsque la chaîne est pleinement opérationnelle, en boucle fermée, la qualité de la recombinaison doit être évaluée. L'objet de cette thèse est de proposer un nouvel interféromètre adapté à ces deux besoins, c'est-à-dire capable d'encaisser de fortes dynamiques et d'avoir en même temps des capacités de mesure absolue de très grandes précision et justesse, à haute cadence, afin de mesurer et d'analyser le front d'onde résultant de la combinaison des différents lasers sur toute la phase de conception de ces lasers, en boucle ouverte comme en boucle ferméeThe need for the rise in power, peak and medium, of hyper intense laser chains has led to the emergence of a new type of architecture. The principle is to consistently combine a large number of the simplest and most robust elementary lasers possible. The difficulty of ramping up is therefore mainly transferred to the recombination system. Several laboratories around the world have thus decided to get involved in this path. If there are various concepts for the servo loop, there is currently, to our knowledge, no development of a means of absolute metrology of the quality of the final wavefront, and therefore of recombination. This is fundamental for two particular moments in the design of these new architectures.First, it is necessary to know the nature, amplitude and frequency of open loop phase faults in order to properly specify the optical head architecture and the control/command system. Then, when the chain is fully operational, in closed loop, the quality of the recombination must be evaluated. The purpose of this thesis is to propose a new interferometer adapted to these two needs, i.e. capable of withstanding strong dynamics and at the same time having absolute measurement capabilities of very high precision and accuracy, at high cadence, in order to measure and analyze the wavefront resulting from the combination of the different lasers over the entire design phase of these lasers, in open loop as in closed loop
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Junior, Jair De Martin. "Sistema de laser de diodo de cavidade estendida para padrões de frequência." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-29052014-144230/.
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Este trabalho tem como objetivo principal desenvolver uma nova fonte de laser de diodo compacta e robusta, além de um novo drive de controle para serem utilizados em padrões primário de tempo e frequência tipo chafariz de átomo de Césio e padrões compacto baseados em átomos frios. Um dos requisitos para utilização de laser de diodo em padrões primários de tempo e frequência é sua estabilidade em frequência e baixíssimo ruído espectral. Além disto, dada à aplicação embarcada, o laser deve ser extremamente robusto com relação às condições adversas: mecânicas, térmicas e elétricas. Tanto a parte optomecânica, quanto os controles eletrônicos do novo laser foram desenvolvidos neste trabalho. Vale salientar que tal sistema, em sua concepção, é de grande interesse para diversos outros tipos de aplicação, como espectroscopia de gases (LIDAR), referências em outras frequências e experimentos de física atômica e molecular, que possuem elevados níveis de exigência com relação a ruídos espectrais.This work has as main objective to develop a new source of diode laser compact and robust, beyond a new drive control for use in primary of time and frequency standards type cesium atom fountain and compact standards-based cold atoms. One of the requirements for the use of diode laser in primary of time and frequency standards are their stability in frequency and are very low spectral noise. Furthermore, given the embedded application, the laser must be extremely robust with respect to adverse conditions: mechanical, thermal and electrical. Both opto-mechanical part, as the electronic controls of the new laser were developed in this work. It is noteworthy that such a system, in its conception, is of great interest to many other types of applications such as spectroscopy of gases (LIDAR), references in other frequencies and experiments of atomic and molecular physics, which have high levels of demand with respect to spectral noise.
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Lee, Woei Ming. "Optical trapping : optical interferometric metrology and nanophotonics." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/882.
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Bryant, Christian Huw. "Tunable far infrared (TuFIR) spectroscopy of atmospheric species and FIR laser metrology." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388666.
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Kovalchuk, Evgeny. "Optical parametric oscillators for precision IR spectroscopy and metrology." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15759.
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In der vorliegenden Doktorarbeit wird ein Dauerstrich Optisch Parametrischer Oszillator (cw OPO) vorgestellt, der speziell für die hochauflösende Dopplerfreie Molekülspektroskopie und Metrologie entwickelt wurde. Der kontrollierte Zugang zu jeder beliebigen Wellenlänge im breiten Emissionsspektrum von OPOs wie auch das präzise Abstimmen seiner Ausgangsfrequenz über zu untersuchende molekulare und atomare Übergänge stellten lange Zeit Probleme dar, deren Lösung die Grundzielsetzung dieser Arbeit war. Das im Laufe dieser Arbeit entwickelte System hat diese Ziele vollständig erreicht, was durch verschiedene Messungen und Anwendungen demonstriert wurde. Zu diesem Zweck wurde ein neues OPO-Design mit einem Intracavity-Etalon entwickelt und aufgebaut, wobei der OPO auf dem Konzept eines einfach-resonanten cw OPOs mit resonanter Pumpwelle basiert. Die OPO-Ausgangsstrahlung zeigt sehr gute Langzeitstabilität und Spektraleigenschaften, welche durch direkte Frequenzvergleichsmessungen mit einem optischen Methan-Frequenzstandard im Infraroten bestimmt wurden. Eine Idler-Linienbreite von 12 kHz und ein Modensprung-freier Betrieb des OPOs über einen Zeitraum von einigen Tagen wurde beobachtet. Außerdem wurde gezeigt, dass ein OPO zu einer hochstabilen optischen Referenz phasengelockt und somit seine Frequenz sehr genau kontrolliert und durchgestimmt werden kann. Als erste erfolgreiche Anwendung eines OPOs in der Dopplerfreien Spektroskopie wurde ein Aufbau zur Frequenz-Modulationsspektroskopie in Methan realisiert. Weiterhin, wurde der entwickelte cw OPO mit einem femtosekunden optischen Frequenzkamm kombiniert, um eine neue Idee für eine kohärente Verbindung zwischen dem sichtbaren und dem infraroten Spektralbereich zu realisieren. Als erste Demonstration dieser Technologie wurde ein direkter absoluter Frequenzvergleich zwischen einem Jod-stabilisierten Laser bei 532 nm und einem Methan-stabilisierten Laser bei 3390 nm durchgeführt.This thesis presents a continuous-wave optical parametric oscillator (cw OPO), specially developed for high-resolution Doppler-free molecular spectroscopy and metrology. The basic objective was to solve the long-standing problem of controlled access to any desired wavelength in the wide emission range of OPOs, including the ability to precisely tune the output frequency over the molecular and atomic transitions of interest. The system implemented during this work fully achieves these goals and its performance was demonstrated in various measurements and applications. For this aim, a new design for the OPO cavity with an intracavity etalon was implemented, extending the concept of a cw singly resonant OPO with resonated pump wave. The newly developed device demonstrates very good long-term stability and spectral properties, which were determined in direct beat frequency measurements with a methane infrared optical frequency standard. Thus, an idler radiation linewidth of 12 kHz and mode-hop-free operation of the OPO over several days were observed. Furthermore, it was shown that an OPO can be phase locked to a highly stable optical reference and thus much more precisely controlled and tuned. As the first successful application of OPOs in Doppler-free spectroscopy, a frequency modulation spectroscopy setup for detection of sub-Doppler resonances in methane was implemented. Furthermore, the developed cw OPO was integrated with a femtosecond optical frequency comb to realize a new concept for a coherent link between the visible and infrared spectral ranges. As a first demonstration of this technique, a direct absolute frequency comparison between an iodine stabilized laser at 532 nm and a methane stabilized laser at 3390 nm was performed.
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Yahyavi, Zanjani Matin, Henning Zeidler, André Martin, and Andreas Schubert. "Application of Laser Scanning as a Pre-machining metrology technique in Jet-ECM." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-227104.
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In Electrochemical Machining (ECM), where the material removal takes place based on the anodic dissolution of the workpiece material, the working distance is one of the most important parameters. Especially in Jet Electrochemical Machining (Jet-ECM), where a micro nozzle is moved over the initial surface of the workpiece in order to apply an electrolytic free jet to produce the desired shapes, the distance between the nozzle and the workpiece becomes even more important. On the one hand a small working distance is aspired to achieve high current densities resulting in a high efficiency of the process. On the other hand the working distance needs to be large enough to avoid damages on the micro nozzle caused by electrical discharges or mechanical contact. Hence, the adjustment of the working gap is essential to realize a precise, effective and secure Jet-ECM process.
The control of the gap size is done based on the data gathered before machining by surface measurement. Until now, the initial surface has been detected by electrostatic probing through moving the nozzle stepwise to the work piece surface and detect the voltage drop between the nozzle and the work piece. With this strategy, only a limited number of points can be detected within adequate time. Hence, in most cases only three points of the initial surface are detected in order to adjust the working distance according to the planar inclination of the workpiece. The coordinates of the three detected points are used to calculate the normal vector of the initial surface. In recent studies, another strategy was analysed, which is realized by dividing the surface into smaller areas and respectively calculating the normal vector of each area in order to obtain more accurate data of the initial surface. A further strategy is to use probing along the machining path of the tool and to gather the coordinates of a number of points along the path.
The above mentioned methods usually do not ensure the precise control of the gap size especially for the surfaces with complex geometry with locally confined convex and concave shapes and are highly affected by the size of the probe. In this study, the application of a laser scanner is investigated for the measurement of the workpiece surface before machining to gather the required data for the adjustment of the working distance during Jet-EC machining of complicated surfaces.
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King, Steven Anthony. "Sub-hertz optical frequency metrology using a single ion of 171Yb+." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:428b1f40-3b5d-475e-aebc-c062b987e3f2.
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Optical frequency standards offer the possibility of a step improvement of up to two orders of magnitude in the accuracy with which the SI second can be realised. 171Yb+ possesses two dipole-forbidden optical transitions that are promising candidates for a redefinition of the second. In this thesis, absolute frequency measurements of these two transitions are presented. A number of experimental upgrades have been implemented, which have resulted in a large reduction in both the statistical and systematic uncertainties associated with the measurements and have improved both the reliability and simplicity of the experimental setup. In particular, the replacement of two frequency-doubled Ar+-pumped Ti:sapphire lasers with extended cavity diode lasers has eliminated the downtime associated with their maintenance. Additionally, the introduction of polarisation modulation on the cooling light has allowed the residual bias magnetic field required for laser cooling to be reduced by a factor of thirty. The first measurement at the National Physical Laboratory (NPL) of the frequency of the 2S1/2 (F = 0) → 2D3/2 (F′ = 2) electric quadrupole (E2) transition at 436 nm is presented. The transition frequency was measured against a hydrogen maser using a femtosecond optical frequency comb, and was determined with a relative standard uncertainty of 1.3 × 10−14. A commercial diode-based laser system was then implemented in order to drive the 2S1/2 (F = 0) → 2F7/2 (F′ = 3) electric octupole (E3) transition at 467 nm. The laser frequency was actively stabilised to the ultra-narrow atomic absorption with a resolved linewidth of 11 Hz, allowing the acquisition of ninety hours of frequency data measured relative to the NPL’s primary frequency standard CsF2. Combined with a thorough evaluation of the systematic perturbations, the total fractional uncertainty in the absolute frequency of the transition has been reduced by a factor of twenty to 1 × 10−15. Recent complementary results from Physikalisch-Technische Bundesanstalt (PTB) show that the E3 transition in 171Yb+ has the potential to be a highly accurate and reproducible optical frequency standard, and to date these measurements demonstrate the best international agreement between trapped ion optical frequency standards.
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Pickering, Christopher James Derwent. "The development of laser speckle metrology for the study of vibration and fluid flow." Thesis, University of Southampton, 1987. https://eprints.soton.ac.uk/52266/.
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Two original applications of laser speckle metrology are presented. First, a portable Laser Speckle Interferometer is described which allows the Engineer to simply point a laser beam at target surface in order to measure its vibration velocity amplitude and phase. This non-contacting capability complements an accelerometer where use of the latter is precluded; i.e. hot, light or rotating surfaces. The mechanisms which determine the noise floor of the interferometer are examined and minimisation procedures are defined. A prototype instrument is described which has a dynamic range of 60 dB over a frequency range of d.c. - 20 kHz which is adequate for general purpose use. Three applications are reported which exploit the non-contact capability of the instrument. Second, the application of Laser Speckle Photography to fluid flows is described and the development of an entirely new technique is introduced which is more appropriately named Particle Image Velocimetry (PIV). In PIV, the instantaneous two-dimensional velocity of a fluid flow is measured by taking a double-exposure photograph of a thin sheet of light within a seeded flow. Pointwise processing of the resulting transparency with a laser beam produces Young's fringes in the far field diffraction pattern whose spacing and orientation are measured to find the local fluid velocity within the illuminated region. It is shown both theoretically and by experiment, that the signal to noise ratio of these fringes and hence measurement accuracy, is significantly improved by using a two-step photographic process. In addition, it is shown that this process allows the use of more sensitive photographic films which reduce the laser power requirement and hence the cost of a PIV system. Two methods of fringe analysis are examined and it is shown that, by preprocessing the fringe pattern to remove the low frequency pedestal component, fringe spacing errors of less than 1% are achieved. It is also shown that this method significantly decreases the time required to measure fringe spacing when compared with conventional Fourier methods. In addition, a method of decreasing the overall time required to analyse an entire PIV transparency based on detection of the presence of particle images within the illuminated region is described.
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Riedel, Robert [Verfasser], and Markus [Akademischer Betreuer] Drescher. "Pulse Metrology Tool and Burst-Mode Laser Amplifier for the Free-Electron Laser in Hamburg / Robert Riedel. Betreuer: Markus Drescher." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2013. http://d-nb.info/1045730491/34.
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Harper, Matthew R. "Control and measurement of ultrafast pulses for pump/probe-based metrology." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/430.
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Greeff, Gabriel Pieter. "A study for the development of a laser tracking system utilizing multilateration for high accuracy dimensional metrology." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/3181.
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MScEngThesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Accurate dimensional measurement devices are critical for international industrial competitiveness for South Africa. An overview of all the necessary components of a laser tracking system using a multilateration technique for very accurate dimensional metrology is presented. A prototype laser tracker station was built to further investigate this type of system. The prototype successfully tracks a target within a volume of at least 200 200 200 mm3, approximately 300 mm away from the tracker. This system includes the mechanical design of a prototype tracker station, electronic implementation of ampli cation and motor control circuits, a tracking control algorithm, microcontroller programming and interfacing, as well as a user interface. Kinematic modelling along with Monte Carlo analyses nd the main error source of such a tracker as the beam steering mechanism gimbal axes misalignment. Multilateration is also motivated by the results found by the analysis. Furthermore, an initial sequential multilateration algorithm is developed and tested. The results of these tests are promising and motivate the use of multilateration over a single beam laser tracking system.
AFRIKAANSE OPSOMMING: Dit is van kritieke belang dat Suid-Afrika akkurate dimensionele metingstoestelle ontwikkel vir internasionale industriële medinging. 'n Oorsig van al die nodige komponente vir 'n Laser-Volgsisteem, wat slegs van multilaterasie gebruik maak om baie akkurate drie dimensionele metings te kan neem, word in hierdie projek voorgestel. 'n Prototipe Laser-Volgsisteem-stasie word gebou om so 'n sisteem verder te ondersoek. Die prototipe slaag wel daarin om 'n teiken, binne 'n volume van 200 200 200 mm3 op 'n afstand van omtrent 300 mm te volg. Die sisteem sluit die meganiese ontwerp van die sodanige stasie, elektroniese seinversterking, motorbeheer, 'n volgingsbeheer algoritme, mikroverwerker programeering en intergrasie, asook 'n gebruikerskoppelvlak program in. Kinematiese modelering, tesame met Monte Carlo simulasies, toon aan dat die hoof oorsaak van metingsfoute by so 'n stasie by die rotasie-asse van die laserstraal-stuurmeganisme, wat nie haaks is nie, lê. Die multilaterasie metode word ook verder ondersteun deur dié modelering. 'n Algoritme wat sekwensiële multilateratsie toepas word boonop ontwikkel en getoets. Die resultate van die toetse dui daarop dat die algoritme funksioneer en dat daar voordele daarin kan wees om so 'n metode in plaas van 'n Enkelstraal-Volgsisteem te gebruik.
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König, Kristian Lars [Verfasser], Wilfried [Akademischer Betreuer] Nörtershäuser, and Thorsten [Akademischer Betreuer] Kröll. "Laser-Based High-Voltage Metrology with ppm Accuracy / Kristian Lars König ; Wilfried Nörtershäuser, Thorsten Kröll." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1178672670/34.
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Schuhler, Nicolas Meyrueis Patrick. "Frequency-comb stabilized laser sources for absolute distance metrology at the very large telescope interferometer." Strasbourg : Université Louis Pasteur, 2007. http://eprints-scd-ulp.u-strasbg.fr:8080/684/01/Schuhler2006.pdf.
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Schuhler, Nicolas. "Frequency-comb stabilized laser sources for absolute distance metrology at the very large telescope interferometer." Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/SCHUHLER_Nicolas_2006.pdf.
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PRIMA, un futur instrument du VLTI, utilise un système de métrologie laser pour mesurer les variations de chemin optique internes à l’interféromètre. L’étude présentée dans ce mémoire porte sur le développement, l’intégration et le test de sources lasers stabilisées en fréquence pour ce système de métrologie. Dans une première partie, nous présentons le cahier des charges du système dans le contexte de PRIMA et du VLTI. Nous rappelons les bases de l’interférométrie laser et les problèmes qu’impose son application à PRIMA. Nous en déduisons la nécessité de stabiliser la longueur d’onde du laser sur une référence absolue et exposons l’intérêt de transformer ce système en un système de mesure de distances absolues. Dans une seconde partie, nous décrivons notre contribution à la stabilisation en fréquence d’un laser Nd:YAG sur une raie d’absorption de l’iode. Nous mesurons précisément les performances du système avec un peigne de fréquences optiques auto-référencé. Nous améliorons le système pour satisfaire aux exigences du cahier des charges. La troisième partie est consacrée à la transformation du système en un système de mesure de distances absolues par l’utilisation de l’interférométrie à deux longueurs d’onde. Nous proposons un nouveau concept de source laser qui utilise un peigne de fréquences optiques comme référence de fréquence. Cette source permet de générer un choix sans précédent de longueurs d’onde synthétiques avec une précision relative dans le vide meilleure que 10−11. Nous validons le concept sur un prototype et montrons qu’il peut être utilisé en interférométrie à deux longueurs d’onde pour résoudre une longueur d’onde optiqueThe forthcoming instrument of the Very Large Telescope Interferometer (VLTI), called Phase-Referenced Imaging and Micro-arcsecond Astrometry facility (PRIMA), uses a laser metrology system to monitor the variations of internal path lengths. This dissertation addresses the development, integration and test of frequency stabilized laser sources for the PRIMA Metrology system (PRIMET). In the first part, we present in the context of PRIMA and the VLTI the specifications of PRIMET. We recall the basics of single-wavelength laser interferometry and introduce the problems raised by its application to PRIMET. We present the need for the absolute frequency stabilization of PRIMET laser and the interest for an upgrade of PRIMET towards absolute distance measurements. In the second part, we present our contribution to the absolute frequency stabilization of PRIMET Nd:YAG laser on a transition of iodine. We characterize the system and measure precisely its performance with a self-referenced optical frequency comb. We improve the system to reach the specifications in terms of accuracy and stability of the locking frequency. The third part addresses the upgrade of PRIMET towards absolute distance measurements by the use of two-wavelength interferometry. We propose a new concept of two-wavelength laser source frequency stabilized on an optical frequency comb. This permits the generation of an unprecedented large choice of synthetic wavelength with a relative accuracy better than 10−11 in vacuum. We validate the concept on a prototype and shows that it can be used to resolve an optical wavelength. Finally, we propose to apply this concept to the upgrade of PRIMET
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Smith, Kevin Boyd. "Modeling, Performance Evaluation, Calibration, and Path Planning of Point Laser Triangulation Probes in Coordinate Metrology /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487935125880273.
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Nilsson, Bengt. "Interferometric 3-D Camera for Shape and Deformation Measurements using Ultra Short Laser Pulses." Doctoral thesis, KTH, Production Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3321.
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Wheeler, Natalie. "Molecular and atomic confinement in large core photonic microcells for slow light and laser metrology applications." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538142.
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This thesis describes developments in the fabrication and applications of photonic microcells (PMCs). A PMC is a length of gas-filled hollow core-photonic crystal fibre (HC-PCF) that is hermetically sealed by splicing both ends to standard single mode fibre. A PMC enables integration of gas-filled HC-PCF into all-fibre systems with low insertion loss. PMCs have applications in coherent optics and metrology, where specific HC-PCF designs are advantageous. Two types of state-of-the-art HC-PCF, double bandgap HCPCF and large-pitch Kagome fibre, are fabricated. The double bandgap HC-PCF extends the usable bandwidth of the fibre by providing low loss guidance across two transmission bands. The large-pitch Kagome HC-PCF has a record low attenuation of 0.3 dB/m at 800 nm, while maintaining broadband guidance, which is partially attributed to the core shape. Three distinct developments in the field of PMCs are described. Firstly, a record length 20 metre acetylene-filled PMC is fabricated which is the key component in the first demonstration of an all-fibre slow and fast light system based on electromagnetically induced transparency. Secondly, a technique based on fibre tapering is presented which enables low loss integration of large core Kagome HC-PCFs into PMC form. Thirdly, micromirrors are developed and integrated with HC-PCF to confine light in the longitudinal dimension, providing a means to fabricate multi-pass PMCs. Two uncoated micromirrors are used to form a low finesse microcavity in Kagome HC-PCF, with record high fringe visibility using reflections from a silica/air junction. In collaboration with Kansas State University, an acetylene optical reference with sub-10 KHz accuracy and the first acetylene laser based on population inversion are demonstrated using Kagome HC-PCF.Finally, this thesis reports on rubidium vapour loading in HC-PCF with the ultimate aim being the production of a rubidium-filled PMC for applications in metrology. Preliminary results highlight the limited loading distance of the current technique and modified loading schemes are outlined accordingly.
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Zobrist, Tom L. "Application of laser tracker technology for measuring optical surfaces." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195326.
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The pages of this dissertation detail the development of an advanced metrology instrument for measuring large optical surfaces. The system is designed to accurately guide the fabrication of the Giant Magellan Telescope and future telescopes through loose-abrasive grinding. The instrument couples a commercial laser tracker with an advanced calibration technique and a set of external references to mitigate a number of error sources. The system is also required to work as a verification test for the GMT principal optical interferometric test of the polished mirror segment to corroborate the measurements in several low-order aberrations. A set of system performance goals were developed to ensure that the system will achieve these purposes. The design, analysis, calibration results, and measurement performance of the Laser Tracker Plus system are presented in this dissertation.
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Monchocé, Sylvain. "Contrôle et métrologie de la génération d'harmoniques sur miroir plasma." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112344.
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Lorsqu'on focalise une impulsion laser femtoseconde ultraintense à très haut contraste sur une cible solide, le champ laser au foyer est suffisamment important pour ioniser la surface durant le front montant de l'impulsion et former un plasma. Au sein de ce plasma s'établit un gradient de densité résultant de l'expansion hydrodynamique du plasma. Ce plasma très dense, réfléchit le faisceau laser incident dans la direction spéculaire: on parle alors de miroir plasma. Comme l'interaction entre le laser et le miroir plasma est fortement non-linéaire, cela conduit à la génération d'harmoniques d'ordre élevé dans le faisceau réfléchi. Dans le domaine temporel, ce spectre d'harmonique est associé à un train d'impulsions attosecondes. Les objectifs de ma thèse étaient de contrôler expérimentalement cette génération d'harmoniques et d'en mesurer toutes les propriétés. Nous nous sommes intéressés dans un premier temps, à l'optimisation du signal harmonique, puis à la caractérisation spatiale en champ lointain du faisceau harmonique (divergence des harmoniques).Si la caractérisation et le contrôle de ces propriétés sont des points importants pour le développement de la source, ces résultats permettent également une meilleure compréhension de l'interaction laser-plasma à ultra-haute intensité. Ils nous ont notamment permis d'obtenir des informations cruciales sur les dynamiques électronique et ionique du plasma, démontrant ainsi qu'il est possible d'utiliser les harmoniques comme un diagnostic de l'interaction laser-plasma.Nous introduisons également une méthode complètement optique permettant de structurer un plasma in-situ. En tirant partie des propriétés de l'expansion d'un plasma, nous avons pu créer in-situ des réseaux plasmas transitoires, que nous avons ensuite exploités pour réaliser les premières mesures ptychographiques à des intensités de 10^19W/cm^2, permettant de mesurer entièrement, pour la première fois, les propriétés spatiales des harmoniques (taille de source et phase) dans le plan de leur générationWhen an ultra intense femtosecond laser with high contrast is focused on a solid target, the laser field at focus is sufficient enough to completely ionize the target surface during the rising edge of the laser pulse and form a plasma. This dense plasma entirely reflects the incident beam in the specular direction: this is a so-called plasma mirror. As the interaction between the laser and the plasma mirror is highly non-linear, it thus leads to the high harmonic generation (HHG) in the reflected beam. In the temporal domain, this harmonic spectrum is associated to a train of attosecond pulses.The aim of my PhD were to experimentally control this HHG and to measure the properties of the harmonics. We first studied the optimization of the harmonic signal, and then the spatial characterization of the harmonic beam in the far-field (harmonic divergence). These characterizations are not only important to develop an intense XUV/attosecond light source, but also to get a better understanding of the laser-matter interaction at very high intensity. We have thus been able to get crucial information of the electrons and ions dynamics of the plasma, showing that the harmonics can also be used as a diagnostic of the laser-plasma interaction.We then developed a new general approach for optically-controlled spatial structuring of overdense plasmas generated at the surface of initially plain solid targets. We demonstrate it experimentally by creating sinusoidal plasma gratings of adjustable spatial periodicity and depth, and study the interaction of these transient structures with an ultraintense laser pulse to establish their usability atrelativistically high intensities. We then show how these gratings can be used as a `spatial ruler' to determine the source size of the high-order harmonic beams roduced at the surface of an overdense plasma. These results open new directions both for the metrology of laser-plasma interactions and the emerging field of ultrahigh intensity plasmonics
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Lantigua, Christopher. "Metrology of Volume Chirped Bragg Gratings Recorded in Photo-Thermo-Refractive Glass for Ultrashort Pulse Stretching and Compressing." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5803.
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Chirped Bragg gratings (CBGs) recorded in photo-thermo-refractive (PTR) glass provide a very efficient and robust way to stretch and compress ultra-short laser pulses. These gratings offer the ability to stretch pulses from hundreds of femtoseconds, to the order of 1 ns and then re-compress them. However, in order to achieve pulse stretching of this magnitude, 100 mm thick CBGs are needed. Using these CBGs to both stretch, and re-compress the pulse thus requires propagation through 200 mm of optical glass. This therefore demands perfect control of the glass homogeneity, as well as the holographic recording process of the CBG. In this thesis, we present a study of the CBG parameters that lead to distortions in the quality of diffracted beams. We first present the challenges associated with measuring the quality of these beams and we show that such measurements are not easily achieved using commercial systems that rely on the ISO standard M2 method. Thus, we introduce a new metric of beam quality, which we have coined S2, that is a combination of both the M2 and power in the bucket metrics. Subsequently, we investigate the influence of the CBG parameters on the quality of diffracted beams. In particular, we examine the impact of small optical heterogeneities known as striae, as well as the impact of the optically and thermally induced distortions in the grating. We then use this data to improve the fabrication and characterization of 100 mm long CBGs. Finally, we characterize the performance of CBGs recorded in PTR for stretching and compression of femtosecond pulses using a custom autocorrelation system. We present data on high quality 100 mm long CBGs and an analysis on the correlation between beam quality and the final pulse duration after stretching and re-compressing the pulse.M.S.
Masters
Optics and Photonics
Optics and Photonics
Optics
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Wang, Yuzhou. "Characterizing Property and Microstructure of Ceramic Nuclear Materials with Laser-based Microscopy." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563201433596828.
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Lloyd, David T. "Characterizing the spatial properties of high harmonic generation." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:4c51a956-b3a9-4172-ad17-0e9584a4ffa3.
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This thesis is concerned with describing a novel technique for characterizing the (spectrally resolved) spatial properties of light. The new approach, known as Scanning Interference Method for Integrated Transverse Analysis of Radiation (SCIMITAR), is a specific implementation of a variable-separation two-pinhole interferometer. Evaluation of the series of interference patterns produced by a SCIMITAR measurement allows the transverse profiles of intensity and spatial phase to be retrieved, while at the same time characterizing the spatial coherence of light. Including a diffraction grating in the simple experimental arrangement permits the spectral dependence of the aforementioned quantities to be measured. The SCIMITAR technique was demonstrated by characterizing the spatial properties of high harmonic generation (HHG). Excellent agreement with an alternate characterization technique known as SWORD was observed. The spectral dependence of the harmonic spatial properties was also investigated. Evidence suggesting absorption may play a role in shaping the harmonic intensity and spatial coherence was presented. Treating the harmonic radiation as either a fully coherent or partially coherent beam allowed the intensity width, spatial phase curvature and coherence width of the harmonic radiation source to be deduced. Measurement of the fine variation of the harmonic complex coherence factor (CCF) with pinhole separation revealed distinctive modulations. The Van Cittert-Zernike theorem was modified by including a Gerchberg-Saxton inspired improvement, allowing data missing from the SCIMITAR measurement to be inferred. The harmonic equivalent incoherent source intensity profile was found to be asymmetric with low intensity features isolated away from the optical axis. Calculations of the diffraction pattern produced by illumination of a non-redundant array of pinholes showed that the modulated harmonic properties could adversely influence lensless imaging-type experiments.
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Diaz, Romain. "Métrologie de l'endommagement laser des composants optiques en silice en régime nanoseconde." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4390/document.
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Cette thèse porte sur l'endommagement laser de composants optiques en silice amorphe en régime nanoseconde. Ce matériau diélectrique est l'un des plus couramment utilisés en optique et notamment sur des installations laser de haute énergie telles que le Laser MégaJoule. Afin de garantir le fonctionnement nominal d'une installation, l'endommagement laser des composants optiques doit être compris et maîtrisé. Ce phénomène induit une modification irréversible du matériau modifiant la propagation du faisceau. Dans le régime nanoseconde, l'endommagement laser de la silice est corrélé à la présence de défauts précurseurs qui sont une conséquence de la synthèse et du polissage des composants. L'interaction de ces précurseurs avec le laser va dépendre des caractéristiques de ce dernier. Une première étude est consacrée à la métrologie des impulsions utilisées en laboratoire pour étudier l'endommagement laser. Une seconde étude porte sur les mécanismes d'amorçage des dommages sur la face de sortie des composants optiques faits de silice. Une dernière partie porte sur l'influence de la propagation non linéaire sur l'endommagement surfacique et volumique des composants épais faits de siliceIn this thesis, laser-induced damage phenomenon in fused silica components is investigated in the nanosecond regime. This material is one of the most widely used in optics, particularly on high-energy laser facilities such as the Laser MégaJoule. In order to ensure the nominal operation of this kind of laser facility, laser-induced damage on optical components has to be understood and controlled. This phenomenon consists in an irreversible modification of the material. In the nanosecond regime, laser-induced damage is tightly correlated to the presence of precursor defects which are a consequence of the synthesis and the polishing of the components. The interaction between these precursor defects and the laser pulses strongly depends on the laser characteristics. The first study focuses on the metrology of the laser beam used in laboratory to study laser-induced damage. The second one consists in a parametric study of the initiation mechanism on the rear surface of fused silica components. The last part deals with the influence of nonlinear propagation on laser induced damage on the surface and in the volume of thick fused silica samples
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Pariente, Gustave. "Caractérisation spatio-temporelle d’impulsions laser de haute puissance." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS003/document.
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Les lasers de haute puissance permettent d'atteindre des intensités très importantes (jusqu'à 10²²W.cm⁻²). Parvenir à ce niveau d'intensité nécessite de concentrer une quantité modérée d'énergie (de l'ordre du joule) dans un temps très court (de l'ordre de la dizaine de femtosecondes) sur une surface réduite (de l'ordre du μm²). Ces faisceaux sont donc ultra-courts et focalisés à l'aide d'une optique à grande ouverture. Ces caractéristiques signifient que leur diamètre avant focalisation est grand et leur largeur spectrale est importante. Pour cette raison, ces faisceaux sont à même de présenter des distorsions spatio-spectrales (ou couplages spatio-temporels). Après focalisation, ces distorsions ont pour effet une diminution drastique de l'intensité pic. Ceci est d'autant plus vrai que le système laser est puissant et donc que son diamètre et sa largeur spectrale sont grands. En dépit de cet effet néfaste, les couplages spatio-temporels présentent aussi un intérêt lorsqu'ils sont maitrisés. On peut en effet introduire des couplages spatio-temporels de faible amplitude à des fins expérimentales. Dans les années 1990 et 2000, un effort important a été fourni pour permettre la caractérisation et l'optimisation du profil temporel des lasers femtoseconde. Dans le même temps, des solutions d'optique adaptative ont été développées pour contrôler le profil spatial des faisceaux ultra-intenses et obtenir la meilleure tache focale possible. Les systèmes laser de haute-puissance actuels sont maintenant caractérisés et optimisés indépendamment par ces deux types de diagnostics. Par essence, cette approche est aveugle aux couplages spatio-temporels. Seule une caractérisation spatio-temporelle permettrait de mesurer ces distorsions. Il existait déjà des méthodes de caractérisation spatio-temporelle avant le début de cette thèse. Aucun de ces dispositifs n'avait cependant été adapté à la mesure de faisceaux ultra-intenses. Lors de cette thèse, nous avons développé une nouvelle technique de caractérisation spatio-temporelle appelée TERMITES. Cette technique est basée sur un schéma de spectroscopie par transformée de Fourier auto-référencée. TERMITES nous a permis d'effectuer la première caractérisation spatio-temporelle totale d'un laser 100 TW (le laser UHI-100 du CEA Saclay). Les distorsions spatio-temporelles détectées à l'aide de ces mesures ont confirmé la nécessité d'une généralisation de la métrologie spatio-temporelle des lasers de haute puissanceHigh power laser make it possible to reach very high intensities (up to 10²²W.cm⁻²). In order to get to this level of intensity, a moderate quantity of energy (on the order of the Joule) is concentrated in a very short time (on the order of tens of femtoseconds) onto a small surface (on the order of 1 μm²). These beams are therefore ultra-short and focused with a high aperture optic. These features mean that their diameter prior to focus is large and their spectral width is big. As a result, these beams are subject to spatio-spectral distorsions (of spatio-temporal couplings). After focus, these distorsions induce a dramatic reduction of the peak intensity. This situation is all the more true when the laser is more intense and its diameter and spectral width are therefore bigger. Despite their detrimental effects, spatio-temporal couplings can be of great interest when controlled. One can indeed introduce weak spatio-temporal couplings for experimental purposes. In the 1990s and 2000s, a big effort was put in order to characterize dans optimize the temporal profile of femtosecond lasers. Meanwhile, adaptative optics solutions were developed to control the spatial profil of ultra intense laser beams and provide the best focal spot achievable. By nature, this approach is blind to spatio-temporal couplings. Measuring these distorsions requires a spatio-temporal characterization. Before the start of this Phd thesis, spatio-temporal characterization methods already existed. Although none of these devices were ever adapted to the measurement of ultra-intense laser beams. During this Phd Thesis, we developped a new spatio-temporal characterization technique which we called TERMITES. This technique is based on a self-referenced Fourier transform spectroscopy scheme. TERMITES made it possible for us to perform the first total spatio-temporal characterization of a 100 TW laser (UHI-100 at CEA Saclay, France). The detection of spatio-temporal distorsions with the help of these measurements confirmed the need for a generalization of spatio-temporal characterization of ultra-high power lasers
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Jeandet, Antoine. "Spatio-temporal characterization of femtosecond laser pulses using self-referenced Fourier transform spectroscopy Spatio-temporal structure of a petawatt femtosecond laser beam Controlling the velocity of a femtosecond laser pulse using refractive lenses." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS089.
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La technologie actuelle des lasers ultrabrefs permet de délivrer des impulsions d'une énergie de quelques dizaines de joules dont la durée est de l'ordre de la dizaine de femtosecondes. Focaliser fortement de telles impulsions permet d'obtenir des valeurs d'éclairement considérables, qui sont notamment utilisées pour générer des faisceaux de particules relativistes. Le bon fonctionnement des lasers de ultra-haute intensité nécessite un excellent contrôle des propriétés du faisceau en tout point de la chaîne d'amplification. Développer un tel niveau de contrôle exige de pouvoir mesurer les imperfections temporelles et spatiales des impulsions avec une très grande précision. Cependant, les instruments de mesure utilisés jusqu'à présent négligent un aspect important de la structure des impulsions lasers, qui est lié aux couplages spatio-temporels. Ces derniers représentent une classe particulière d'imperfections, dont l'influence sur les expériences d'ultra-haute intensité a longtemps été négligée. Les rares instruments capables de mesurer ces défauts spécifiques sont pour la plupart inadaptés à la caractérisation de faisceaux de haute énergie. Le travail présenté dans cette thèse a porté sur l'instrument TERMITES, qui permet la caractérisation totale d'impulsions ultrabrèves, ainsi que leur restitution en trois dimensions. TERMITES est une technique auto-référencée qui est basée sur la spectroscopie par transformée de Fourier résolue spatialement. Une première partie de la thèse présente l'étude détaillée et l'optimisation de l'instrument TERMITES. Dans un deuxième temps, différents systèmes laser sont caractérisés grâce à cet instrument, permettant ainsi d'établir la première revue expérimentale des différentes origines de couplages spatio-temporels dans les lasers ultrabrefsCurrent ultrashort laser technology makes it possible to generate pulses lasting a few tens of femtoseconds, with energies of up to tens of joules. Strongly focusing such pulses produces ultra-intense fields that are notably used to generate relativistic particle beams. Proper operation of ultra-intense laser facilities requires to control the temporal and spatial properties of ultrashort pulses. Until now, measurement devices used for this purpose have neglected an important aspect of ultrashort pulses structure, which is linked to spatio-temporal couplings. Spatio-temporal couplings are a particular kind of defects in ultrashort pulses, of which the influence on ultra-intense experiments has been largely overlooked until recently. The rare instruments capable of measuring spatio-temporal couplings are hardly scalable to high-energy laser beams. This thesis is dedicated to TERMITES, a device for the full characterization of ultrashort laser beam, which is used to provide their three dimensional shape in space and time. TERMITES is a self-referenced technique based on spatially-resolved Fourier-Transform Spectroscopy. The first part of this work presents the detailed study of TERMITES, as well as the optimization of its design. Multiple laser systems are then characterized using the instrument. The obtained results are used to establish the first experimental review of spatio-temporal couplings origins in ultrashort lasers
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Kiesewetter, Dietrich. "Dynamics of Near-Threshold, Attosecond Electron Wavepackets in Strong Laser Fields." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1544447128975478.
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Lim, Jinkang. "All-fiber frequency comb employing a single walled carbon nanotube saturable absorber for optical frequency metrology in near infrared." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/7423.
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Doctor of PhilosophyDepartment of Physics
Brian R. Washburn
Optical frequency combs produced by mode-locked fiber lasers are useful tools for high precision frequency metrology and molecular spectroscopy in a robust and portable format. We have specifically investigated erbium doped fiber mode-locked lasers that use single-walled carbon nanotubes as a saturable absorber. We have, for the first time, developed and phase- stabilized a carbon nanotube fiber laser (CNFL) frequency comb. The carbon nanotube saturable absorber, which was fabricated using an optically driven deposition method, permits a high repetition frequency (>150 MHz) since an optical nonlinearity of fibers is not used for mode-locking. The CNFL comb combined with a parabolic pulse erbium doped fiber amplifier (EDFA) has shown a compact, robust, and cost-effective supercontinuum source. The amplified pulse from the parabolic pulse EDFA was compressed with a hollow-core photonic bandgap fiber, which produced a wave-breaking-free pulse with an all-fiber set-up. The stabilized comb has demonstrated a fractional instability of 1.2 ×10[superscript]-11 at 1 sec averaging time, the reference-limited instability. We have performed optical frequency metrology with the CNFL comb and have measured an optical frequency, P(13) which is a molecular overtone transition of C2H2. The measured frequency has shown a good agreement with the known value within an uncertainty of 10 kHz. In order to extend the application of the CNFL comb such as multi-heterodyne dual comb spectroscopy, we have investigated the noise of the CNFL comb and particularly, the broad carrier envelope offset frequency (f[subscript]0) linewidth of the CNFL comb. The primary noise source is shown to be white amplitude noise on the oscillator pump laser combined with the sensitivity of the mode-locked laser to pump power fluctuations. The control bandwidth of f[subscipt]0 was limited by the response dynamics of the CNFL comb. The significant reduction of comb noise has been observed by implementing a phase-lead compensation to extend control bandwidth of the comb and by reducing the pump relative intensity noise simultaneously. Therefore the f[subscipt]0 linewidth has been narrower from 850 kHz to 220 kHz. The integrated phase noise for the f[subscipt]0 lock is 1.6 radians from 100 Hz to 102 kHz.
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Galtier, Sandrine. "Spectroscopie haute précision de la transition 1S-3S de l'atome d'hydrogène en vue d'une détermination du rayon du proton." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066554/document.
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La précision des calculs théoriques d'électrodynamique quantique dans l'atome d'hydrogène est actuellement limitée par la constante de Rydberg et la distribution de charge du proton. La comparaison entre ces calculs et les mesures expérimentales de deux fréquences de transition dans l'hydrogène permet d'extraire ces deux constantes. La mesure de la transition 1S-2S est la plus précise à ce jour avec une incertitude relative de 10-15. L'objectif de mon travail de recherche est d'améliorer la précision de mesure de la fréquence de la transition 1S-3S, pouvant être utilisée comme la deuxième mesure nécessaire.La transition 1S-3S est sondée par une excitation à deux photons à 205 nm, permettant de s'affranchir de l'effet Doppler du 1er ordre. Ce faisceau UV est produit par somme de fréquence dans un cristal non linéaire. L'onde lumineuse délivrée par un laser Titane-saphir à 894 nm est sommée avec un faisceau à 266 nm produit par doublage d'un laser Nd-YO4. Cette somme de fréquence délivre un faisceau continu à 205 nm d'une puissance de 15 mWLa distribution de vitesse du jet atomique, dont la connaissance est indispensable pour évaluer l'effet Doppler du 2ème ordre, est déterminée grâce à l'effet Stark motionnel où l'action d'un champ magnétique produit un décalage en fréquence quadratique en vitesse.Les fréquences des deux lasers sources sont mesurées à l'aide un peigne de fréquence optique.La fréquence de la transition 1S-3S est finalement déterminée avec une incertitude relative de 10-12. Sa valeur conduit à une valeur préliminaire du rayon du proton qui serait en contradiction avec celle préconisée par le CODATAThe uncertainty of the Quantum Electrodynamics calculations for hydrogen atom is currently limited by the knowledge of the Rydberg constant and the proton charge radius. Those two quantities can be extracted from the comparison between the theoretical predictions and two different frequency measurements on hydrogen.The 1S-2S transition frequency is one measured with the highest resolution with a relative uncertainty of 10-15. The aim of this thesis is to improve the determination of the 1S-3S transition, which can be used as the second precise measurement. The 1S-3S two-photon transition is excited at 205 nm. This UV light beam is generated by frequency mixing in a non-linear crystal. An 894 nm light delivered by a Ti:Sa laser is mixed with a 266 nm light beam generated by a quadrupled Nd:YVO4 laser. A reliable 15 mW continuous radiation at 205 nm is then produced. The frequencies of both lasers are measured simultaneously using an optical frequency comb referenced to a cesium clock. To evaluate the second-order Doppler effect, the velocity distribution of the atomic beam is determined thanks to a motional Stark effect. This effect is realized with a static magnetic field which induces a velocity-dependent quadratic frequency shift. Finally, the frequency of the 1S-3S transition is determined with a relative uncertainty of 10-12 which is accurate enough to contribute to the “proton size puzzle”. However, depending on the velocity distribution used in the analysis, the obtained value agrees or not with the present recommended CODATA value
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Corbas, Vincent. "Cartographie d’espèces chimiques en combustion par tomographie et spectroscopie d’absorption multifaisceaux." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS491/document.
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La concentration des espèces chimiques comme H₂O, CO₂, CO, K, HCl ainsi que les grandeurs thermodynamiques comme la pression et la température sont des paramètres clés pour comprendre les réactions de combustion. Ces données permettent de mieux caractériser la combustion dans les foyers aéronautiques et aussi d’affiner les simulations numériques qui permettent d’aider à la conception de moteurs. L’objectif est d’améliorer leur efficacité avec un meilleur rendement et une diminution du rejet de gaz polluants. L’objectif de la thèse est de développer une méthode de caractérisation optique non-intrusive permettant d’obtenir des cartographies de concentrations d’espèces chimiques, de température et de pression dans ces flammes. Cette méthode consiste à acquérir des spectres d’absorption à plusieurs positions et angles dans l’écoulement réactif. L’inversion spectral de ces données permettra de remonter quantitativement aux concentrations chimiques, à la pression et à la température. Dans la thèse, nous avons choisi de combiner cette inversion spectrale à un algorithme de tomographie permettant d’améliorer la résolution spatiale. La méthode développée est appelée Tunable Diode Laser Absorption Tomography (TDLAT). Deux axes de recherches ont été poursuivis au cours de la thèse. Le premier a consisté à développer plusieurs spectromètres d’absorptions associés à un système mécanique de balayage spatial de la flamme. Dans un second temps, nous avons cherché à développer un algorithme de tomographie non-linéaire permettant d’exploiter les séries de spectres d’absorption pour obtenir la résolution spatiale. Les principaux résultats obtenus en simulation ont permis d’optimiser l’algorithme et aussi d’adapter son fonctionnement aux configurations de mesures représentatives des bancs de combustion. Les principaux résultats de mesures ont été enregistrés dans une flamme de laboratoire et sur un banc de combustion de propergol solideChemical species densities like H₂O, CO₂, CO, K, HCl and thermodynamic data like pressure and temperature are keys parameters to understand combustion. Measurements of these parameters are great help to validate or complement numerical simulations aiming at improving engine design and efficiency. The current thesis presents the development of an optical characterization method leading to two dimensional maps of chemical densities, pressure and temperature in combustion flames. This method consists to acquire absorption spectra at different positions and angles around the reactive flow. The spectral inversion of these data can be used to recover quantitatively chemical densities, pressure and temperature. In this thesis, we have chosen to combine this spectral inversion with a tomographic algorithm in order to obtain results with improved spatial resolution. The developed method is called Tunable Diode Laser Absorption Tomography (TDLAT).Two research directions have been followed during the thesis. The first consisted to develop several absorption spectrometers associated with a mechanical scanning device of the flame. In a second time, we have searched to develop a non-linear tomographic algorithm in order to process absorption spectra series in order to obtain spatial resolution. The main results obtained in simulations have led to an optimization of the tomographic algorithm in order to adapt its functioning to measurements configurations characteristics of combustion benches. The main measurements results have been acquired in a laboratory flame and in a solid propellant combustion bench
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Demeyere, Michaël. "Noncontact dimensional metrology by triangulation under laser plane lighting : development of new ambulatory instruments / Métrologie dimensionnelle sans contact par triangulation sous éclairage par plans laser : développement de nouveaux instruments ambulatoires." Université catholique de Louvain, 2006. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-03092006-140258/.
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Dimensional metrology is of prime importance in the industrial and scientific domains, particularly in the field of quality control of manufactured products. In robotics too: without dimensional sensors, robots would be nothing else more than automatons, going through the same repetitive tasks again and again in a carefully controlled environment. This thesis deals with a noncontact measurement technique involving active vision, called triangulation under laser plane lighting. This optomechatronic method consists in projecting a laser sheet on an object or a surface under test, and analyzing the intersecting curve on an image taken by a camera. It allows making a wide variety of dimensional, noncontact and nondestructive, measurements (length, area, volume, diameter, curvature, reverse engineering,...). The original approach of the work is that the focus is brought on the determination of specific, restricted dimensional information on objects of diverse, but a priori known, shapes with the objective of achieving metrological performances in agreement with the industrial requirements. Furthermore, ambulatory instrumentsi.e. devices that are at least portable, or even handheldare exclusively aimed, using low-cost components. Another objective is to obtain systems for which an industrial transposition to innovative instrumental products is feasible. The text is divided in two distinct parts, both strongly correlated. The first one deals with all the theoretical aspects of the method: camera model, passage from 2-D image to 3-D scene, image processing, calibration, accuracy analysis... The performances of the developed models are also studied, in terms of robustness and repeatability. The second part describes four innovative applications of our own: the diameter measurement of cylindrical and of spherical objects, dimensional measurements in the building sector and the determination of the road surface microtexture. The achieved accuracies are globally of about 1%.
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Casanova, Alexis. "Caractérisation et réduction de la gigue temporelle de lasers ytterbium ultrabrefs pompés par diode." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0931.
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Ce travail de thèse se concentre sur la caractérisation et la correction de la gigue temporelle de lasers ultrabrefs, c'est-à-dire avec une durée d'impulsion sub-picoseconde, pompés par diode et avec un milieu à gain dopé à l'Ytterbium. Ce type de source laser a bénéficié d'un développement industriel rapide depuis le début des années 2000 et a trouvé de très nombreuses applications, notamment dans le domaine scientifique pour des expériences résolues en temps (FELs, accélérateurs de particules, OPAs...). Dans ce type d’applications, la réduction de la gigue des impulsions permet d’accéder à de meilleures résolutions temporelles et permet d’observer des phénomènes physiques extrêmement brefs.Dans ce travail, la gigue d'oscillateurs lasers ultrabrefs à verrouillage de mode passif a été corrigée et caractérisée en générant un signal d'erreur par photo-détection directe d'une part et par corrélation croisée optique d'autre part. La correction de la gigue temporelle par corrélation croisée optique permet d'obtenir une gigue résiduelle inférieure à 5fs, de l'ordre de la durée d'un cycle optique, avec des oscillateurs compacts et industriels. Une gigue résiduelle de ce niveau permet d’accéder à des expériences résolues en temps exigeantes en termes de stabilités temporelles des sources de lumière utilisée, par exemple une expérience d’interaction lumière-matière de type pompe-sonde avec une source laser à électrons libres.Un nouvel instrument basé sur la corrélation statistique des signaux de gigue générés par deux canaux de corrélations croisées optiques a été mis en place. Un tel instrument a permis de caractériser complètement la gigue temporelle d'oscillateurs à des fréquences de Fourier supérieures à la dizaine de kiloHertz lasers ultrabref en atteignant un plancher de bruit sub-zeptoseconde. La gigue additive d'amplificateurs lasers ultrabrefs a également été caractérisée par corrélation croisée optique, cela afin d'acquérir une compréhension globale de la gigue introduite par une chaîne laser ultrabrève amplifiée.Les mesures effectuées ont permis d’analyser les origines physiques de la gigue dans un système laser ultrabref. Ces résultats permettront à terme d’améliorer la correction de la gigue sur les systèmes industriels étudiés ainsi que de développer de nouvelles sources laser ultrabrèves intrinsèquement moins bruyantes. Une telle étude expérimentale pourra également servir de support pour éventuellement enrichir le modèle théorique des perturbations dans un laser ultrabrefThe main scope of this PhD work is to characterize and reduce the timing jitter of optical pulses with sub-picosecond duration, emitted by diode-pumped ultrafsat lasers with Ytterbium doped gain media. Such laser sources have been rapidly enhanced by a high-grade and efficient industrial development, giving access to numerous novel applications, especially in the fields of applied physics and chemistry with time-resolved experiments based on interaction between light and matter. In this latter topic resides a constant need to minimize the laser pulse train timing jitter in order to access physical phenomena with extremely short timescales such as electrons recombination.Two main detection techniques have been studied to characterize the timing jitter from passively modelocked laser oscillators. The first technique is based on direct photo-detection in the microwave domain whilst the second technique makes use of the balanced optical cross-correlation. Residual timing jitter from industrial compact laser oscillators has been reduced below 5fs, close to an optical cycle period. This performance makes the laser oscillators produced by Amplitude-Systemes already suitable for challenging time-resolved pump-probe experiments, in the presence for example of a free electron laser source.Timing jitter analysis has been enhanced by studying the cross-spectrum from jitter signals generated from two balanced optical cross-correlators. This technique allowed the entire characterization of the timing jitter density spectrum from laser oscillators above the ten-kiloHertz Fourier frequency with a sub-zeptosecond noise floor. Additive timing jitter from ultrafast laser amplifiers has also been studied with optical cross-correlation and gives a global comprehension of the timing jitter from a complete high-energy ultrafast laser chain.The collected measurments will be conducive to design a more adapted and performant timing synchronization system for industrial laser sources. A better knowledge of the non-trivial jitter sources, dependent on the laser parameters, will also allow to design intrinsically low-noise new laser sources based on the Ytterbium gain media. The cross-spectrum technique developed could be of use to characterize other laser technologies and to investigate the theoretical perturbation model of ultrafast lasers with a better experimental insight
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Tournemenne, Florian. "Impact des défauts d'aspect sur la propagation d'un laser de puissance." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0189/document.
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Chaque faisceau d'un laser de puissance, tel que le Laser MégaJoule, est mis en forme et voit son énergie amplifiée à l’aide d’une centaine de composants optiques tels que des plaques de verre amplificateur, des lentilles, des miroirs, des lames de phase, des réseaux... 'Evidemment ces composants ne sont pas parfaitement réalisés et ils présentent à leurs surfaces des défauts de fabrication. Ces imperfections peuvent être dues aux outils de polissage des composants, aux dépôts antireflet ou même apparaitre au cours de la phase d’exploitation ou de remédiation du composant. Ces défauts contribuent à une baisse des performances du Laser MégaJoule que ce soit au niveau de l’énergie déposée au centre de la chambre d’expériences ou à l’endommagement accéléré des composants optiques placés en aval. Actuellement la norme ISO 10110-7 est utilisée pour spécifier les défauts d’aspect. Cependant elle manque de justification pour les besoins d’une chaine laser de puissance. Dans le cadre de la thèse nous nous intéressons exclusivement à l’endommagement fratricide local des composants optiques. Un défaut présent à la surface du composant module l’onde lumineuse par phénomène de diffraction. Un << point chaud >> peut apparaitre dans le faisceau laser augmentant alors la densité locale surfacique d’énergie appliquée aux composants suivants. La loi d’endommagement prédit une augmentation de la probabilité d’endommagement puisque la densité d’énergie est modifiée. Une première étude, fondée sur les équations de Fresnel, met en évidence les paramètres intéressants à spécifier pour prédire les intensifications engendrées par des défauts typiques. Le lien entre paramètres du défaut et intensifications diffractées est, ensuite, validité expérimentalement sur des cas réels de défauts. Une seconde étude établit un seuil exprimé en puissance en deçà duquel l'hypothèse d'une propagation linéaire, selon les équations de Fresnel, est valide. La cohérence des résultats donnés par le seuil en puissance et par la simulation numérique renforce l’idée voulant que la propagation d’un << point chaud >> en présence d'effet Kerr soit sensiblement différente de celle d’un faisceau gaussien. Fort de ces deux résultats nous sommes en capacité d'établir une spécification des défauts d’aspect en ayant une meilleure compréhension de l’endommagement fratricide localEach beam of a high power laser facility, such as the Laser MégaJoule, is shaped and amplified thanks to hundreds optical components such as amplifier slabs at Brewster’s angle, lenses, mirrors, phase plates, diffraction gratings... Of course, all these components cannot be perfect; there are some defects on their surface. These imperfections appear at each stage of the life of the component, during polishing, coating, or mitigation process or when the component is used on the facility. They have a huge impact on the energy losses delivered on the target and they decrease the resistance of downstream components to intense light. The ISO 10110-7 standard is currently used to specify the visual defects. However, this standard is poorly justified and do not fit a high power laser needs. In this thesis, we are focused on the fratricide effect. Light propagates through a defect, then, some intensity modulations appear along the propagation. The damage law states that high energy density leads to an increase of the damage probability. Firstly, we investigate the characteristic parameters of the defect morphology linked to the formation of downstream << hot spots >>. Then, the link between these typical parameters and the high intensifications are confirmed by experiments on real defects. Secondly, a power criterion is demonstrated to guarantee the linear propagation hypothesis. This criterion is compared to numerical simulations and it is shown how the nonlinear propagation, induced by Kerr effect, can be different between the << hot spot >> formed by a defect and a Gaussian beam. Finally, the results are used to improve the visual defect specification thanks to a better understanding of the fratricide effect
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Holá, Miroslava. "Pokročilé interferometrické metody pro souřadnicové odměřování." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-364822.
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This thesis addresses particular topics in the field of the length metrology for nanometrology. Nanometrology deals with dimensional measurements of micro- and nanostructures with a high spatial resolution. It typically combines a microscope imaging with a precise coordinate measurement, usually capable of nanometre resolution using the state-of-art laser interferometry techniques. The development in this field is driven, among others, by emerging advanced nanotechnologies that demand to push further the capabilities and limits of the interferometric techniques to make the nanometre-level dimensional measurement of nanostructures possible. The principal limitations of current systems are the environmental conditions and especially the fluctuations in the refractive index of air. The theoretical part of this thesis aim at analysis of individual parts of laser interferometer. I oriented myself on the study of their advantages/disadvantages and further also the possibilities of their industrial applications. The second part of the thesis presents my work that focused on the influence of the refractive index of air (RIA) on the measurement uncertainty. I experimentally demonstrated an interferometric system with a self-cancellation RIA fluctuations: a transparent photodetector is used for the measurement of the standing wave along the axis of a passive resonator, where the resonator also serves as a reference for the laser wavelength stabilisation. Another optical arrangement, based on a setup of several Michelson interferometers, represents a combination of an interferometer and a refractometer into a single system. This setup was used to study the behaviour of the ambient airflow with respect to the optical path difference and physical separation of the interferometer’s and refractometer’s path. Based on the experimental results I proposed new arrangements for shape measuring interferometers, which combine length interferometry and a tracking refractometer for the direct compensation of RIA fluctuations with geometrically adjacent optical beams. The results indicate an improvement in RIA fluctuation induced uncertainty by a factor of 100. Third part describes the design and implementation of interferometric systems for specific applications. For the industrial environment I developed a compact interferometric displacement gauge which is designed to allow nanometre level measurement using a simplified interferometer construction. For coordinate measurement of the position of the sample up to six degrees of freedom, I realised a compact modular interferometric system, which represents a unique setup together with a stabilised laser source. To measure the position of the sample in an electron beam writer chamber, I designed and implemented a differential interferometer that works in the near infrared domain and uses a new detection method developed for this system. In the fourth part I describe the realisation of a high-speed interferometer with a differential arrangement, which allows evaluation of high-cycle fatigue in material engineering. This method of studying high-cycle fatigue should be beneficial for both the basic research and the engineering practice.
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Bridge, Elizabeth Michelle. "Towards a strontium optical lattice clock." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:a96e73fe-f17b-4738-be1d-34429b5b4a05.
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Due to the recent success, in terms of accuracy and precision, of a number of strontium optical lattice optical frequency standards, and the classification of the 5s2 1S0 to 5s5p 3P0 transition in neutral strontium as a secondary definition of the SI unit of the second, many new strontium lattice clocks are under development. The strontium optical lattice clock (Sr OLC) at the National Physical Laboratory (NPL) is one such project. This thesis describes the design and build of the NPL Sr OLC, discussing the considerations behind the design. Details of the first cooling stage are given, which includes the characterisation of a novel permanent-magnet Zeeman slower by measurements of the longitudinal velocity distributions and loading of the MOT at 461 nm. Development of a narrow linewidth laser system at 689 nm is described, which is used for initial spectroscopy of the second-stage cooling transition. In particular, this work describes progress towards two independent ultra-narrow linewidth clock lasers. The new generation of strontium lattice clock experiments have focused on characterising the systematic frequency shifts and reducing their associated fractional frequency uncertainties, as well as reducing the fractional frequency instability of the measurement. One focus of the Sr OLC at NPL is to help characterise the frequency shift of the clock transition due to black-body radiation (BBR), which is currently the largest contributor to the uncertainty budget of the measured clock frequency. Our approach, discussed here, is to make a direct, differential measurement of the shift with the atoms housed alternately in environments of differing temperatures. Better characterisation and control of the BBR frequency shift of the strontium clock transition is crucial for the future of the Sr OLC as a leading frequency standard.
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Martinez, Garcia Juan Manuel. "Color characterization of a new laser printing system." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES032/document.
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Grâce aux progrès récents dans le domaine des nanotechnologies il est maintenant possible de colorer des plaques de verre avec du dioxyde de titane contenant de l’argent par irradiation laser. L’une des caractéristiques de ce procédé est que le rendu couleur des échantillons produits diffère quand ceux-ci sont observés en réflexion (spéculaire ou diffuse) ou en transmission, ainsi que quand on polarise la lumière. Ce nouveau procédé d’impression laser que l’on a appelé PICSLUP (pour Photo-Induced Colored Silver LUster Printing system) permet de produire des images couleur gonio-apparentes.L’objectif de cette thèse est de caractériser l’apparence couleur (d’un point de vus colorimétrique et photométrique, et ce selon plusieurs géométries d’observation) de plaques de verre colorées par ce procédé. Ce qui pose de nombreux challenges techniques du fait que le système d’impression utilisé est encore en cours de développement et pas souvent accessible, du fait également de plusieurs spécificités photométriques (surface fortement translucide, fortement spéculaire, forte gonio-chromaticité). Afin de lever de toutes ces contraintes techniques notre première approche a été de caractériser la couleur grâce à un imageur monté sur un microscope. Nous avons pour cela généré par impression laser (avec le système PICSLUS) tout un ensemble d’échantillons couleur en faisant varier de manière exhaustive différents paramètres d’impression (temps d’exposition du faisceau laser, longueur d’onde, distance focale). Afin d’obtenir des mesures couleur précises nous avons ensuite développé une méthode de calibrage couleur spécifique dédiée à la mesure de surfaces fortement spéculaires. La précision de cette méthode de calibrage, appliquée aux échantillons créés par le système PICSLUP, est comparable à celles relevées dans l’état de l’art. À partir des couleurs obtenues on peut estimer la gamme des couleur (color gamut) qui peut être obtenue par ce système d’impression, en particulier pour la géométrie spéculaires 0º:0º, et étudier l’influence des différents paramètres d’impression ainsi que l’effet de la polarisation. Quoique les mesures réalisées sous microscope avec la géométrie spéculaire 0°:0° soient particulièrement utile pour étudier les propriétés colorimétriques et photométriques produites par le système PICSLUP, ces mesures ne sont pas suffisantes pour caractériser complètement ce système. En effet, l’apparence couleur des échantillons produits varie également en fonction de la géométrie d’éclairement et d’observation, il est donc nécessaire de caractériser le système PICSLUP selon d’autres géométries que la seule géométrie 0°:0°. Nous avons donc développé une autre méthode de caractérisation basée sur l’utilisation d’un imageur hyperspectral à géométrie ajustable, ce qui nous a permis de caractériser un ensemble donné d’échantillons couleur produits par le système PICSLUP. Ces échantillons ont été mesurés, en recto-verso, en transmission (avec la géométrie 0°:0°), en réflexion spéculaire (avec la géométrie 15°:15°), et en réflexion hors spéculaire (avec la géométrie 45°:0°). Grâce à ces mesures on a pu estimer pour différentes géométries d’observation les changements de gamme des couleurs qui peuvent être obtenus par le système PICSLUP. Le volume qui circonscrit chacune de ces gammes de couleur peut être modélisé par une forme concave qui contient beaucoup de zones éparses, ce qui revient à dire que certaines couleurs ne peuvent être directement obtenues par impression. Afin d’obtenir une forme convexe, plus dense quelque soit la zone d’étude considérée, nous avons testé avec succès une nouvelle méthode d’impression qui consiste non plus à imprimer des aplats (zones uniformément colorées par juxtaposition de lignes laser identiques) mais à imprimer des demi-tons (par juxtaposition de lignes laser de différentes couleurs). Cette méthode est basée sur le principe de l’halftoning et sur un nombre limité de primaires couleur pré-sélectionnéesRecent progresses in nanotechnologies enabled the coloration of glass plates coated with titanium dioxide containing silver by laser irradiation. The colored samples display very different colors when obtained by reflection or transmission of light; in specular or off-specular directions; and with or without polarizing filters. This new laser printing technology, that we call PICSLUP (for Photo-Induced Colored Silver LUster Printing system), enables the production of gonioapparent color images.The goal of this study is to perform a multi-geometry photometric and color characterization of this complex system. This task posed technical challenges due to the system being in a development stage, especially a low availability of the printing material; and due to the photometric properties of the prints: high translucency, high specularity and strong goniochromaticity. In order to overcome these constraints, our first approach was based on color characterization by microscope imaging. The data set used consisted in printing an exhaustive number of micrometric color patches, produced by varying the different laser printing parameters: exposure time, laser wavelength, laser power, and laser focusing distance. To achieve accurate color measurements with samples produced with the PICSLUS system, we successfully developed a color calibration method especially tailored for highly specular materials, whose accuracy is good in comparison to previous studies in the literature on camera color calibration. From the colors obtained, we could estimate the color gamut in the 0º:0º specular reflection geometry and study the influence of the different printing parameters as well as polarization. Although the measurements with microscope imaging in the 0°:0° specular geometry were very useful to study the properties of the colors produced by the PICSLUP technology, they were not sufficient to fully characterize the system, since the samples exhibit very different colors according to the respective positions of the viewer and the light source. With this in mind, we assembled a geometry-adjustable hyperspectral imaging system, which allowed us to characterize a representative subset of the colors that can be produced with the system. The samples were measured from both recto and verso faces, in the 0°:0° transmission, 15°:15° specular reflection, and 45°:0° off-specular reflection illumination/observation geometries. From these measurements, the color gamuts of the system were estimated in the different geometries. The volumes delimited by the colors obtained were concave and contained many sparse regions with very few samples. In order to obtain more continuous, dense and convex color gamut volumes, we successfully tested the generation of new colors by juxtaposing printed lines of different primaries with halftoning techniques. In order to circumvent the need to physically characterize all the different color that can be produced with halftoning using the numerous primaries available, we also tested and fitted existing halftoning prediction models, and obtained a satisfactory accuracy. The use of halftoning not only increased the number colors that can be produced by the system in the different geometries, but also increased the number of different primaries that can be produced when we consider as a whole the set of colors produced by the same printed patch in multiple geometries. Finally, based on the different properties demonstrated by the samples produced by the PISCLUP system, we explored some imaging and security features with colors obtained from our characterization, and propose further potential applications for this new goniochromatic laser printing technology
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Cambier, Valentin. "Horloge à réseau optique à atomes de mercure exploitant un 2D-MOT : durée de vie de l'état 3P0 et mesures de fréquence." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS512.
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Les horloges optiques ont révolutionné la métrologie du temps et des fréquences depuis le début des années 2000. Dans ma thèse, j’ai travaillé avec une horloge à réseau optique basée sur l’atome de mercure. Le mercure est un candidat prometteur pour les horloges à réseau du fait de sa faible sensibilité au rayonnement du corps noir. Durant ma thèse, j’ai exploité un piège magnéto optique 2D pour pré-refroidir les atomes de mercure avant leur interrogation. Cela permet non seulement de piéger un plus grand nombre d’atomes mais aussi d’améliorer le cycle d’horloge en diminuant le temps de cycle total. Ces améliorations ont permis de mesurer la durée de vie de l’état 3P0 et de participer à des campagnes de mesure à l’échelle européenne entre différentes horloges située à plusieurs centaines de kilomètres l’une de l’autre. Nous avons ainsi pu mesurer pour la première fois le ratio de fréquence entre le mercure et l’ion ytterbium +Optical clocks have changed time and frequency metrology since the beginning of the 2000’s. In my thesis, I worked on a mercury optical lattice clock. Mercury is a promising candidate for optical clocks thanks to its weak sensitivity to blackbody radiation shift. During my PhD, I took benefit of a magneto optical trap in two dimensions (2D-MOT) to pre-cool the mercury atoms before the interrogation phase. It allows us not only to trap much more atoms but also to improve the clock cycle by decreasing the total cycle time. These improvements made possible the lifetime measurement of the 3P0 state and to participate to measurement campaigns at the European scale between different clocks located a few hundreds of kilometres apart. As a consequence, it was possible to measure for the first time the frequency ratio between mercury and Yb+ ion
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Thapa, Rajesh. "Cr:forsterite laser frequency comb stabil[a]zation and development of portable frequency references inside a hollow optical fiber." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/994.
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Piracha, Mohammad Umar. "A laser radar employing linearly chirped pulses from a mode-locked laser for long range, unambiguous, sub-millimeter resolution ranging and velocimetry." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5372.
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Light detection and ranging (lidar) is used for various applications such as remote sensing, altimetry and imaging. In this talk, a linearly chirped pulse source is introduced that generates wavelength-swept pulses exhibiting ~6 nm optical bandwidth with > 20 km coherence length. The chirped pulses are used in an interferometric lidar setup to perform distance measurements with sub-millimeter resolution (using pulses that are a few meters long), at target distances > 10 km, with at least 25 dB signal-to-noise ratio at the receiver. A pulse repetition rate of 20 MHz provides fast update rates, while chirped pulse amplification allows easy amplification of optical signals to high power levels that are required for long range operation. A pulse tagging scheme based on phase modulation is used to demonstrate unambiguous, long range measurements. In addition to this, simultaneous measurement of target range and Doppler velocity is performed using a target moving at a speed of over 330 km/h (205 mph) inside the laboratory. In addition to this, spectral phase modulation of the chirped pulses is demonstrated to compensate for the undesirable ripple in the group delay of the chirped pulses. Moreover, spectral amplitude modulation is used to generate pulses with Gaussian temporal intensity profiles and a two-fold increase in the lidar range resolution (284 um) is observed.ID: 031001421; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Peter J. Delfyett.; Title from PDF title page (viewed June 18, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 93-104).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Mang, Matthias M. "Interferometric spatio-temporal characterisation of ultrashort light pulses." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:163c5374-1466-4c4d-a0f5-c4e66b27e2ac.
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The main topic of this thesis is the development of novel diagnostics for the characterisation of infrared femtosecond and extreme-ultraviolet (XUV) attosecond pulses. High-resolution interferometric methods are applied to high harmonic radiation, both to measure the properties of the XUV light and to relate this information to the physics of the fundamental generation process. To do so, a complete high harmonic beamline has been built and optimised to enable the observation of strong signatures of the macroscopic response of the medium. The distinct spatial characteristics of long and short trajectories are studied, as well as the interference between them. An interferometric measurement allows the extraction of the atomic dipole phase, which gives direct access to the sub-cycle electron dynamics. A major focus of this thesis is on the development of a novel method which simultaneously characterises two independent electric fields as a function of any degree of freedom in which it is possible to shear one of the beams. Since each field alternately takes the role of the reference to retrieve the other field, this technique is referred to as mutual interferometric characterisation of electric-fields (MICE). One of the key features of MICE is that no sheared but otherwise identical replica of the test pulse needs to be generated, which is a typical requirement of self-referencing techniques. Furthermore, no a priori information is needed for the reconstruction. The strength and the wide applicability of MICE are demonstrated using two fundamentally different examples. First, the temporal pulse profiles of two infrared femtosecond pulses are simultaneously reconstructed in a single laser shot. In the second demonstration, the MICE approach is used to simultaneously reconstruct the wavefronts of two high harmonic beams. Having this new technique at hand, the phase properties of the different quantum trajectories are compared. All pulse characterisation techniques implicitly assume full coherence of the beam. This, however, is often not the case in practice, in particular when dealing with complex XUV light sources. Here the standard characterisation techniques fail to provide an accurate description of the electric field. Instead, the electric field must be seen as a statistical mixture of different contributions to the overall field. Here an interferometric experiment is first proposed and then performed involving multiple lateral shears to measure the two-point correlation function of high harmonic radiation. This directly provides information about the existence and the magnitude of partial coherence of high harmonics.
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Hopper, David J. "Investigation of laser frequency stabilisation using modulation transfer spectroscopy." Queensland University of Technology, 2008. http://eprints.qut.edu.au/16667/.
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Optical frequency standards are necessary tools for accurate measurement of time and length. In practice these standards are stabilised laser systems locked to a known frequency reference. These references are typically the resonant frequencies of the atoms of an absorption medium that have been theoretically calculated to a high degree of accuracy. This thesis describes a combination of experimental and theoretical research performed on modulation transfer spectroscopy (MTS)--a technique used to frequency stabilise a laser in order to produce an accurate frequency reference--with emphasis placed on developing techniques and procedures to overcome the limitations found in existing MTS stabilised laser systems. The focus of the thesis is to generate a highly accurate frequency reference by researching the system parameters that will increase the signal to noise ratio and improve the accuracy of the reference through refinement of the signal structure. The early theoretical interpretation of MTS was effectively a low absorption approximation that occurs at low pressures. This approximation ignores the depletion of beam energy through absorption and is a distinct limitation of the theoretical model in its ability to accurately predict the influence of a range of system parameters on signal strength and structure. To overcome this limitation a 3-D (or volumetric) analysis was developed and is presented here for the first time. This volumetric model is a measure of two depleted beams interacting collinearly in an absorbing medium of iodine and is described to accurately predict the signal maximum as a function of pressure for all wavelengths. This model was found to be more accurate in predicting the influence of system parameters on the signal strength and structure, including that of pump beam intensity, pressure, saturation parameter, cell length and modulation parameters. The volumetric model is a novel approach to MTS theory but is more complex computationally than the traditional low pressure model and therefore more difficult to implement in many situations. To overcome this problem a hybrid model was developed as a combination of the low pressure and volumetric models. The comparison between the rigorous volume model and the hybrid model indicate that there is a deviation in the signal strength at high pressures. However, the agreement was very good in the pressure regimes that are commonly used to realise actual frequency references. Comparison of the hybrid model to experimental data was performed over a range of different wavelengths (532 nm, 543.5 nm, 612 nm and 633 nm) and found to be in close agreement. This gives confidence in the model to accurately predict signal strength and structure in any situation. Three mechanisms have been identified that limit the accuracy of frequency references due to the creation of residual amplitude modulation (RAM) where it shifts the frequency of the reference. The influence of RAM is included in the hybrid model as a ratio of the amplitude modulated and frequency modulated components of the saturating beam. These RAM production mechanisms result from the modulation of the saturating beam, the overlap of the beams in the medium, and the differential absorption of the sidebands in the medium. While the first mechanism has been previously reported the latter two are discussed here in detail for the first time. RAM generated by the modulators used (acousto-optic or electro-optic modulators) was typically of the order of 10% to 12%, depending on the excursion of the created sidebands. RAM generated by an asymmetric beam overlap with the modulators used was found to be as large as 30%. A combination of these two independent mechanisms can be used to provide a "RAM-free" state of the system by using one to cancel the effects of the other. The third RAM generation process--medium induced RAM--is difficult to remove but through a careful combination of absorption related parameters--namely, pump intensity, cell length, pressure and detector phase--the effects of RAM can be removed, leading to a distortion free MTS signal. Further investigation into the predictions provided by the hybrid model shows that there is a complex relationship between cell length and the optimum pressure required for maximum signal strength, such that longer cell lengths will not necessarily improve the signal strength. This is contrary to conventional thinking and is important in the MTS design process to reduce unnecessary costs and improve the signal to noise ratio and frequency accuracy. Optimisation of frequency stabilised laser systems using MTS are generally performed using trial and error. Comparison of these optimum parameter values to those predicted by the hybrid model show that for popular wavelengths such as 532 nm they are similar. In addition, the hybrid model is able to predict the frequency shifts that arise within the system parameters used and has shown that existing systems being used at 532 nm, 633 nm and 778 nm could improve their signal to noise ratio and accuracy through a variation in the parameters. A methodology based on the hybrid model is presented that can be used to calculate the optimum parameters for maximum signal strength and a "RAM-free" state for any wavelength. This systematic approach can therefore be used to guide the design of actual frequency stabilised laser systems prior to and during the design process.
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Germain, Florent. "Fluorescence plane induite par laser appliquée à l'étude d'un écoulement de convection mixte - Caractérisation et simulation." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2015. http://www.theses.fr/2015ESMA0006/document.
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La métrologie non-intrusive est une composante essentielle de la recherche expérimentale en mécanique des fluides. La connaissance instantanée des champs de vitesse et de température apportent des informations essentielles à la compréhension des phénomènes instationnaires aérothermiques. Toutefois, si les mesures de vitesses sont aisément réalisées, l’obtention de champs de température s’avère plus complexe. L’une des voies étudiées pour y parvenir estla Fluorescence Plane Induite par LASER, ou PLIF. Son principe repose sur l’acquisition de signaux lumineux de fluorescence, dépendants de la température, consécutifs à l’excitation du milieu par un faisceau LASER intense. En particulier, la PLIF acétone à deux longueurs d’onde emploie l’acétone comme traceur fluorescent et deux LASER comme source d’excitation pour s’affranchir de la dépendance en concentration en acétone. Toutefois, selon la longueur d’onde,l’énergie LASER ou la gamme de température explorée, la PLIF-2λ peut s’avérer difficile à mettre en oeuvre du fait d’un manque de sensibilité, lié à un signal de fluorescence trop faible.Dès lors, plusieurs étapes correctives visant à améliorer le rapport signal-sur-bruit peuvent être mises en oeuvre. Le présent travail s’intéresse ainsi à déterminer la pertinence de cette méthode métrologique dans la qualification aérothermique d’un écoulement de convection mixte autour d’un cylindre chauffé, en couplant la PLIF-2λ à la Vélocimétrie par Imagerie de Particules(PIV). Le montage expérimental est détaillé, ainsi que les processus correctifs et l’étalonnage mis en place pour la PLIF. Les résultats expérimentaux sur le cylindre chauffé sont ensuite présentés et comparés aux travaux de la littérature, puis un modèle de la fluorescence et des caméras employées est élaboré pour permettre d’estimer la précision atteignable en pratique selon la longueur d’onde, l’énergie LASER, la concentration et les caméras, et ainsi rendre possible la présélection des équipements nécessaires aux travaux futursNon-intrusive metrology is essential in experimental fluid mechanics experiments. In particular, simultaneous acquisition of instantaneous velocity and temperature fields offers valuable insights in instationnary aerothermal behaviours. However, if instantaneous velocity fields can be acquired quite easily using the Particles Image Velocimetry technic (PIV), instantaneous temperature fields are much more complex to obtain. Plannar Laser Induced Fluorescence (PLIF) is one of the technics allowing such a measurement. The emitted LASER light induces excitation of acetone molecules, the tracer in the studied air flow. Then, the fluorescence following de-excitation, which is temperature-dependant, is recorded. In particular, 2 λ-PLIF uses dual wavelength LASER excitation to remove acetone concentration dependency in the measurement. Yet, depending of the wavelengths, the LASER energy or the temperature range investigated, using 2 λ-PLIF can be difficult due to a very low temperature sensitivity and very dim fluorescence. To solve those issues and improve signal-to-noise ratio, acquired images can be corrected according to different parameters in an interative process. Present work is dedicated to evaluate efficiency of corrected 2 λ-PLIF applied to the study of a mixed convection flow around a heated cylinder in the 20-300 C temperature range. The goal is to obtain aerothermal qualification of the flow thanks to simultaneous 2 λ-PLIF and PIV. In the present work, experimental bench is detailled as well as the calibrating and correcting process of the 2 λ-PLIF. Then, experimental results are discussed and confronted to results from litterature. Finally, a model of the fluorescence and camera-generated noise is discussed and used to generate simulated fluroescence images and determine the impact of all parameters (wavelengths, LASER energy, acetone concentration and camera intensification gain) on the measurement precision and thus enable adequate choice of equipments for next experiments
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Bao, Chengheri. "Analyse par interférométrie laser de la striction diffuse et localisée dans des tôles d'aciers." Thesis, Troyes, 2016. http://www.theses.fr/2016TROY0014/document.
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L’évolution du champ de localisation des déformations plastiques des métaux ductiles a été suivie par interférométrie de granularité laser (ESPI) au cours d’une sollicitation de traction uniaxiale. Il a été montré que le modèle mathématique utilisé, croisement de deux bandes rectilignes, décrit bien l’évolution du champ de vitesse de déformation depuis la striction diffuse jusqu'à rupture. Les caractéristiques physiques de la localisation, telles que la largeur des bandes, leur orientation et leur vitesse de déformation maximale ont été identifiées quantitativement. Leur évolution a été suivie et analysée sous plusieurs facteurs d’influence, qui sont à la fois microscopiques, tels que la taille de grains et la structure cristalline, et macroscopiques, comme la géométrie de l’éprouvette et la direction de son prélèvement par rapport à la direction de laminage, et la vitesse de traction. Il a été trouvé que les bandes de localisation rétrécissent au cours de la striction et leur orientation évolue également. Ces évolutions, le mode de striction et le moment de transition entre la striction diffuse et localisée sont influencés différemment par ces facteursThe evolution of the plastic strain localization field of ductile metals was followed by electronic speckle pattern interferometry (ESPI) during a uniaxial tensile test. It was shown that the mathematical model, a system of two crossing straight bands, describes accurately the evolution of the strain rate field from diffuse necking up to rupture. The physical characteristics of the localization, such as the width of the bands, their orientations and maximum strain rates were identified quantitatively. Their evolutions were followed and analyzed from several influencing factors, which are both microscopic, such as grain size and crystal structure, and macroscopic, like the geometry of the specimen and the direction in which the specimen were cut with respect to the rolling direction, and the pulling speed. It has been found that the bands narrow down during the necking process and their orientations were also changing. These evolutions, the necking mode and the transition between the diffuse and localized necking are influenced differently by these factors
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Thiel, Valérian. "Analyse modale d'un peigne de fréquences femtoseconde : corrélations spectrales classiques et quantiques." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066661/document.
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Dans cette thèse, nous étudions les applications aux mesures de précision à la limite quantique d'un peigne de fréquence optique dans le régime femtoseconde, ainsi que les fluctuations de sa structure spectrale. Pour cela, nous utilisons un formalisme emprunté au domaine de l'optique quantique. Nous démontrons que la structure du peigne peut effectivement être décomposée sur une base de modes, dont chacun est relié à un paramètre physique. À l'aide de mesures projectives, nous montrons qu'il est alors possible d'accéder à une information portée par le champ électromagnétique (tel le délai temporel d'une impulsion), ainsi qu'aux fluctuations de la source laser (en analogie, la gigue temporelle). Finalement, nous proposons l'élaboration d'un système pour générer deux faisceaux quantiques "comprimés en temps", puisqu'ils permettent de mesurer un délai avec une sensibilité accrue par rapport à l'utilisation de ressources classiquesIn this thesis, we investigate the usage of an optical femtosecond frequency comb for precision measurements at the quantum limit, as well as the fluctuations of the combs structure. We use a formalism that is borrowed from quantum optics to describe classical phenomenon. We show indeed that the comb structure can be decomposed on a basis of modes, where each of these is attached to a given physical parameters. In a projective measurement scheme, we show that it is then possible to measure an information carried by the electromagnetic field (such as a delay in time) as well as fluctuations from the laser source (in that example, the timing jitter). We finally propose a scheme to generate two beams that are "squeezed in time", since they allow to measure a delay with a better sensitivity than using classical resources