Dissertations / Theses on the topic 'Optical experiments'
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Sinclair, Gavin. "Experiments using holographic optical tweezers." Thesis, University of Glasgow, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428751.
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Bennet, Adam Joseph. "Optical Experiments on Shared Quantum Correlations." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/365930.
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Shared quantum correlations find application in a wide range of modern quantum information protocols. This thesis presents several optical experiments towards the improved certification of shared quantum correlations, using photonic qubits.
The first experiment demonstrates the Einstein–Podolsky–Rosen (EPR) steering effect with no detection loophole. Polarisation–entangled photon pairs generated in a Sagnac interferometer were used to test new loss–tolerant EPR steering inequalities. To test the robustness of the loss–tolerant EPR steering nequalities, a transmission loss of −4.3dB was introduced using a 1km optical fibre loop, finding inequality violations for n = 10 and n = 16 measurement settings with no detection loophole (equating to a total loss of
87%). The findings demonstrate how the new loss–tolerant protocols can be used to certify the EPR steering effect for arbitrarily high losses, and may find application in one–sided device–independent quantum key distribution protocols.
The second experiment introduces EPR steering in the context of an EPR steering game. The rules of the game allow for certification of shared quantum correlations via EPR steering inequalites without requiring trust in devices or parties external to a quantum referee. In particular, the experiment successfully demonstrates EPR steering in a measurement–device independent framework; a framework which has typically been accessible only through Bell inequality violations. The findings suggest the possibility for quantum–refereed one–sided device–independent quantum key distribution protocols.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Science, Environment, Engineering and Technology
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Lee, Shiao-Chiu. "Axial offset effects upon optical fiber sensor and splice performance." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/91128.
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A kind of intensity modulated fiber sensor utilizing axial offset parameter is proposed. The theoretical analysis and experimental characteristics of this sensor are described.
All the theoretical results derived in this thesis are based on assuming a uniform power distribution in the fibers. An expression of coupling efficiency of central dipped parabolic graded index fibers due to axial offset is derived. The results show less sensitivity to axial offset for the central dipped fibers than for the parabolic profile fibers without a dip. Expressions of coupling efficiency of graded index fibers due to axial offset for several different values of a are also derived. The results show that sensitivity increases as the value of a decreases. A general expression of coupling efficiency which is valid for small values of axial offset is derived. This expression exhibits a linear relationship between coupling efficiency and small axial offset.
Coupling efficiencies versus fiber end separation and axial offset of step index fibers have been measured. The measurements show that coupling efficiency is much more sensitive to axial offset than end separation. A simple construction of the axial offset fiber sensor is described. An approximate linear relationship between the output power and the mechanical loading has been obtained for this sensor. Several ways of increasing the sensitivity of this sensor are discussed.M.S.
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Figueiredo, Rafael Carvalho 1982. "Ultrafast electro-optical switching of semiconductor optical amplifiers = modeling and experiments." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260748.
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Orientador: Evandro ConfortiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-26T17:49:28Z (GMT). No. of bitstreams: 1 Figueiredo_RafaelCarvalho_D.pdf: 7764328 bytes, checksum: 3a3b008ba1f610e5a7c3ef694ff3f04d (MD5) Previous issue date: 2015
Resumo: O desempenho de chaves eletro-ópticas baseadas em amplificadores ópticos a semicondutor (SOA), incluindo experimentos e simulações usando diferentes formatos de pulso na injeção de corrente elétrica, é apresentado. Quatro SOAs com características físicas distintas são analisados de acordo com seu comportamento de chaveamento. Em seguida, com o intuito de melhorar a resposta eletro-óptica dos SOAs, uma nova técnica de injeção de multi-impulso (MISIC ¿ Multi-Impulse Step Injected Current) é apresentada, alcançando tempo de subida ultrarrápido (115 ps) com baixo overshoot (< 30 %) e alto contraste óptico (30 dB). Os resultados obtidos podem permitir aplicações usando SOAs, por exemplo, como chaves eletro-ópticas em redes de Data Centers, reduzindo a latência de chaveamento entre os nós e compensando perdas por divisões do sinal. Além disso, os circuitos equivalentes para três diferentes SOAs (dois encapsulados e um sem encapsulamento) são propostos. Os modelos são validados através de comparações dos resultados numéricos e experimentais, com boa concordância. A modelagem é realizada em programas de análise de circuitos, exigindo pouco recurso computacional e possibilitando a inclusão dos elementos parasitas das montagens de micro-ondas e dos chips dos dispositivos
Abstract: The performance of electro-optical space switches based on semiconductor optical amplifiers (SOA), including experiments and simulations using different formats of the electrical current injection pulses, is presented. Four SOAs with distinct physical characteristics are analyzed according to their switching behavior. Then, to improve the SOAs¿ electro-optical response, a new Multi-Impulse Step Injected Current (MISIC) technique is presented, achieving ultrafast switching time (115 ps) with low overshoot (< 30 %) and high optical contrast (30 dB). The results obtained might enable SOA applications, for example, as electro-optical switches in Data Center Networks, reducing switching latency between nodes and compensating signal¿s splitting losses. Furthermore, the equivalent circuits for three different SOAs (one chip-on-carrier and two encapsulated) are proposed. The models are validated by comparisons involving numerical and experimental results, with good correspondence. The modeling is carried out using circuit analysis software, requiring small computational resources and enabling the inclusion of parasitic elements of SOA devices¿ chip and microwave mounts
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica
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Weber, Markus. "Quantum optical experiments towards atom-photon entanglement." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-37985.
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Ugarov, Andrew. "Transmission experiments over the all-optical network." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38130.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 54-55).
by Andrew Ugarov.
M.Eng.
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Geursen, Reece Wim, and n/a. "Experiments with Bose-Einstein condensates in optical potentials." University of Otago. Department of Physics, 2005. http://adt.otago.ac.nz./public/adt-NZDU20070131.162251.
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We present a detailed experimental investigation into Bose-Einstein condensates loaded into a one-dimensional optical standing wave at the Bragg condition.
The main emphasis of this thesis is the experimental and theoretical investigation into Bragg spectroscopy performed on circularly accelerating Bose-Einstein condensates. The condensate undergoes circular micromotion in a magnetic time-averaged orbiting potential trap and the effect of this motion on the Bragg spectrum is analysed. A simple frequency modulation model is used to interpret the observed complex structure, and broadening effects are considered using numerical solutions to the Gross-Pitaevskii equation.
The second part of this thesis is an experimental investigation into the effect of nonlinearity on the non-adiabatic loading of a condensate into a optical lattice at the Brillouin zone boundary. Results of using a phase shifting technique to load a single Bloch band in the presence of strong interactions are presented. We observe a depletion of the condensed component, and we propose possible mechanisms for this result.
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Walton, Barney Richard. "Optical diagnostics of laser plasma particle acceleration experiments." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418083.
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Smirne, Giuseppe. "Experiments with Bose-Einstein condensates in optical traps." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414271.
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Burns, D. "Experiments with the Cambridge Optical Aperture Synthesis Telescope." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597129.
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The Cambridge Optical Aperture Synthesis Telescope, or COAST, was conceived by Baldwin and co-workers at the Cavendish Laboratory in 1987 as the simplest possible separated element array for optical closure phase imaging. At the outset if was not clear that the technical difficulties associated with co-phasing the multiple elements simultaneously could be overcome. In this dissertation I describe work which spans the transition between the "engineering and construction" phase and the "astronomical" phase of the COAST project. The contents of each Chapter are as follows: • In Chapter 2 we begin by considering the analysis of visibility-amplitude and closure-phase measurements, concentrating in particular upon the problem of model comparison. We develop a Bayesian framework for the problem, which we then use consistently throughout the remainder of the dissertation. • Chapter 3 is primarily concerned with the design and construction of the array and is therefore mainly a review. Also considered are the range of array configurations presenting available and the throughput of the optical beam-combination system. • Chapter 4 describes the practicalities of data acquisition at COAST and also discusses the estimation of visibility amplitudes and closure-phases from the raw data. The first angular diameter measurements from the array illustrate the quality of visibility amplitude data. • Chapter 5 is by far the most important in this work: the first true images from any separated-element optical array are presented. These represent the first proof that closure-phase imaging using a long-baseline optical interferometer is possible. • In Chapter 6 we consider observations of Betelgeuse which are important both technically and astrophysically. • Chapter 7 is concerned with observations of the Mira-type variable star R Leo. These revealed a pulsation-phase coherent variation in angular diameter at four wavelengths across two periods during 1996 and 1997.
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Sun, David. "Optical signal processors: novel computer models and experiments." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42233.
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The concept of incorporating optical fiber delay lines as signal processors is investigated. These signal processors are discrete-time filters implemented using optical fiber delay lines in the form of optical fiber couplers advantages of such a filter include the ability to eliminate the need for electro-optical conversion or at least postpone the conversion to a point where the electronics may be simplified. In addition, these optical signal processors exhibit all the advantages afforded traditional optical fiber systems. Furthermore, these devices allow high-speed signal processing rates greater than 1GHZ which rival the performance of the most advanced electronic counterparts available today.
In this thesis, optical signal processors are investigated in detail. First, the fundamental signal processing concepts and optical component background is discussed for the analysis of the devices are developed. Subsequently, various configurations of optical signal processors are discussed and novel computer models for these configurations using Z-transform theory are presented. Lastly, experimental verification is presented of the rudimentary models and a unique approach is presented that will allow the creation of optical signal processors with a flexibility never achievable before.Master of Science
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Ley, M. D. "The quantum theory of linear optical amplifiers, saturable absorption and optical interference experiments." Thesis, University of Essex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375649.
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Karotki, Aliaksandr. "Simultaneous Two-Photon Absorption of Tetrapyrrolic Molecules: From Femtosecond Coherence Experiments to Photodynamic Therapy." Thesis, Montana State University, 2003. http://etd.lib.montana.edu/etd/2003/karotki/KarotkiA03.pdf.
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Simultaneous two-photon absorption (TPA) in tetrapyrrolic molecules is studied and its applications to two-photon coherence gratings and singlet oxygen generation for photodynamic therapy are demonstrated in this thesis. First ever comprehensive study of TPA properties of tetrapyrrolic molecules is conducted in this work. Two-photon transitions in two key spectral regions, red to green and blue to near-UV (transition wavelengths) are investigated. Physical mechanisms leading to enhancement of TPA cross section in tetrapyrroles are elucidated. Porphyrin molecules with greatly enhanced two-photon cross sections are obtained. Spectral coherence interference gratings are created by means of two-photon excitation with pairs of phase-locked femtosecond pulses in tetrapyrrolic molecules. First, gratings are detected by means of persistent spectral hole burning, which constitutes the first ever demonstration of spectral hole burning by simultaneous absorption of two photons. Next, the gratings are detected in fluorescence spectrum, which we use to study zero-phonon lines and phonon sidebands in two-photon transitions. Application of tetrapyrrolic molecules to two-photon photosensitization of singlet molecular oxygen is investigated. First, TPA properties of some known one-photon photosensitizers are investigated. Then, a new class of TPA based photosensitizers with greatly enhanced two-photon cross sections is developed. The generation of singlet molecular oxygen upon two-photon excitation of the new photosensitizers demonstrated for the first time, which opens up new perspectives for two-photon photodynamic therapy.
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Ullah, Arif. "Delta-kicked rotor experiments with an all-optical BEC." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/12048.
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This thesis deals with an investigation of the chaotic dynamics of an atom optics ��-kicked rotor (AOKR) system, a paradigm of classical and quantum chaos. The AOKR rotor is realized by subjecting a Bose-Einstein condensate (BEC) of ������Rb atoms to a periodic potential. The potential in the form of a standing wave, obtained from a far detuned laser beam is turned on and off periodically in time, producing short pulses (kicks) of laser light. For certain values of the period between the kicks, resonant effects known as quantum resonances are observed that are purely quantum effects. Quantum resonances have been examined in the AOKR for a series of kicks. For large number of kicks, the width of these resonances have been shown to become narrow. Higher order resonances corresponding to fractional Talbot times have been observed in the system. These quantum resonant effects have been found to depend sensitively on the initial velocity of the atoms. The first three primary resonances have been studied in detail, by measuring the momentum distribution and the kinetic energy of the atoms, for two and four kicks. A sinusoidal dependence of the energy on the initial momentum has been observed for two kicks. By increasing the number of kicks, the system becomes extremely sensitive to the initial momentum of the atoms. For four kicks, a more complex behavior is observed in the system energy. A scheme for investigating Loschmidt time reversal of chaotic dynamics of the atomic deBroglie waves have been described in the AOKR system. It has been demonstrated that the initial wave function of an ensemble of ultracold atoms is restored, after a series of delta-kicks in what is essentially a multiple beam interferometry experiment. During the process, the evolution of the system for a fraction of the atoms with a very small initial momentum is reversed, which results in a narrowing of the momentum distribution. It is hoped that the research presented in this thesis will significantly contribute to the understanding of the connection between the classical and quantum worlds.
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Thoumany, Pierre. "Optical Spectroscopy and Cavity QED Experiments with Rydberg Atoms." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-130845.
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Hay, Rebecca. "Optimising optical tweezers for tracking and force measurement experiments." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8624/.
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Optical Tweezers are a useful tool in many aspects of biology, including cell manipulation and microrheology. They are often used as piconewton force transducers, and are an effective tool for measuring forces acting upon optically trapped particle. To measure such forces, knowledge of the displacement of the particle from the trap centre is always needed. However, due to Brownian motion, a trapped particle is constantly moving and never at rest. In this case, one must track a bead over a set time, so as to gain an average displacement. In this thesis, we have improved and optimised this tracking procedure for biological samples in different ways. In Chapter 1 we discuss how Optical Tweezers work, how they are set up, and how we measure forces using them. In Chapter 2 we redesign a commercial Optical Tweezer Product to improve tracking data results. We also incorporate fluorescence imaging using a compact, low cost, LED illumination source. In Chapter 3 we combine fluorescence microscopy with state of the art Scientific cameras, to increase tracking frame rates and potentially improve our tracking data of fluorescent stained cells. This was part of a collaboration, where I helped to build the setup, took the data (using programs produced by one of my collaborators), and was part of the team to analyse it. In Chapter 4, we look at Low Reynolds number environments and discuss the benefits of viscous forces, and how it may be possible to make non-invasive, less harmful traps for biological samples. Again, this was part of a collaboration, where I was in charge of the experimental part. Here, I built in the static tweezer trap into a tweezer system, took position data and analysed it. A collaborator took control of analysing velocity data. Finally, in Chapter 5, we measure the accuracy of tracking in three dimensions using a stereomicroscope, by placing a Spatial Light Modulator (SLM) at the Fourier plane in the imaging arm. Again, this was a collaboration. I designed and manufactured the illumination head, helped design an acquisition program, and took the data. We discuss how all of these could optimise and advance the tracking of optically trapped particles, especially biological samples. Despite the obvious applications in biology, to allow a fair evaluation of the different tracking techniques, all of our experiments used samples of spherical beads, as they have known specifications, including fluorescence excitation and emission wavelengths, size, and amount of fluorophore stain.
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Keshet, Aviv. "A next-generation apparatus for lithium optical lattice experiments." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79254.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, February 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 167-173).
Quantum simulation is emerging as an ambitious and active subfield of atomic physics. This thesis describes progress towards the goal of simulating condensed matter systems, in particular the physics of the Fermi-Hubbard model, using ultracold Lithium atoms in an optical lattice. A major goal of the quantum simulation program is to observe phase transitions of the Hubbard model, into Néel antiferromagnetic phases and d-wave superfluid phases. Phase transitions are generally accompanied by a change in an underlying correlation in a physical system. Such correlations may be most amenable to probing by looking at fluctuations in the system. Experimental techniques for probing density and magnetization fluctuations in a variety of atomic Fermi systems are developed. The suppression of density fluctuations (or atom "shot noise") in an ideal degenerate Fermi gas is observed by absorption imaging of time-of-flight expanded clouds. Intrap measurements of density and magnetization fluctuations are not easy to probe with absorption imaging, due to their extremely high attenuation. A method to probe these fluctuations based on speckle patterns, caused by fluctuations in the index of refraction for a detuned illumination beam, is developed and applied first to weakly interacting and then to strongly interacting in-trap gases. Fluctuation probes such as these will be a crucial tool in future quantum simulation of condensed matter systems. The quantum simulation experiments that we want to perform require a complex sequence of precisely timed computer controlled events. A distributed GUI-based control system designed with such experiments in mind, The Cicero Word Generator, is described. The system makes use of a client-server separation between a user interface for sequence design and a set of output hardware servers. Output hardware servers are designed to use standard National Instruments output cards, but the client-server nature allows this to be extended to other output hardware. Output sequences running on multiple servers and output cards can be synchronized using a shared clock. By using an FPGA-generated variable frequency clock, redundant buffers can be dramatically shortened, and a time resolution of 100ns achieved over effectively arbitrary sequence lengths. Experimental set-ups for producing, manipulating, and probing ultracold atomic gases can be quite complicated. To move forward with a quantum simulation program, it is necessary to have an apparatus that operates with a reliability that is not easily achieved in the face of this complexity. The design of a new apparatus is discussed. This Sodium-Lithium ultracold gas production machine has been engineered to incorporate as much experimental experience as possible to enhance its reliability. Particular attention has been paid to maximizing optical access and the utilization of this optical access, controlling the ambient temperature of the experiment, achieving a high vacuum, and simplifying subsystems where possible. The apparatus is now on the verge of producing degenerate gases, and should serve as a stable platform on which to perform future lattice quantum simulation experiments.
by Aviv Keshet.
Ph.D.
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Yang, Woo Seuk. "Hydrodynamic analysis of mooring lines based on optical tracking experiments." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-3273.
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Anzuola, Valencia Esdras. "Atmospheric compensation experiments on free-space optical coherent communication systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/308498.
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In the last years free-space optical communications systems for wireless links have been proposed, studied, and implemented mainly due to the higher bandwidth that this technology is able to provide. Still, radio frequency (RF) systems have been maintained in practical wireless communications systems due to the improvement of the microwave sources and the development of high speed electronics. Nowadays the circumstances are changing as a consequence of the increasing data-rate needed in terrestrial and outer space communications. The shift from RF systems to optical communication systems in the free space applications provide a wide set of advantageous characteristics that are motivating the use of these optical technologies in detriment of the RF systems. One of the key reasons is the advantage of working with optical wavelengths in compare to the RF spectral band. As well as the already mentioned increase in the available bandwidth due to the fact that higher optical frequencies directly mean wider bandwidths, the use of optical frequencies lead to a better performance in terms of the received power: for equal antenna sizes the received signal goes inversely as the square of the wavelength. Of the most interest, recent coherent optical communication systems address modulation and detection techniques for high spectral efficiency and robustness against transmission impairments. Coherent detection is an advanced detection technique for achieving high spectral efficiency and maximizing power or signal-to-noise (SNR) efficiency, as symbol decisions are made using the in-phase and quadrature signals, allowing information to be encoded in all the available degrees of freedom. In this context, the effects of Earth's atmosphere must be taken into account. Turbulenceinduced wavefront distortions affect the transmitted beam responsible for deterioration of the link bit error rate (BER). The use of adaptive optics to mitigate turbulence-induced phase fluctuations in links employing coherent (synchronous) detection is poised to reduce performance penalties enabling a more capable next generation of free-space optical communications. In this work, we describe the implementation of a free space optical coherent communication system using QPSK modulation
and heterodyne downconvertion that uses adaptive optics techniques and digital signal processing to mitigate turbulenceinduced phase fluctuations and channel impairments in coherent receivers. A new method for generating atmospheric turbulence based on binary computer generated holography (BCGH) using binary arrays is presented and its performance is evaluated. The feasibility of FSO coherent systems working with adaptive optics is demonstrated and the system performance in terms of the BER is experimentally evaluated under the influence of atmospheric turbulence. The resulting system performance is compared against the theoretical models. The viability of the approach to improve the system efficiency and sensitivity of coherent receivers is experimentally demonstrated.En los últimos años las comunicaciones ópticas en el espacio libre han sido propuestas, analizadas e implementadas debido, principalmente, al gran ancho de banda disponible mediante esta tecnología. Aún así, en la práctica, los sistemas de radiofrecuencia (RF) han sido mantenidos en las aplicaciones comerciales debido a la mejora de los dispositivos utilizados y al desarrollo de equipos electrónicos con gran velocidad de procesado. Hoy en día la situación está cambiando como consecuencia de un incremento en la tasa de transmisión requerida en sistemas de comunicaciones terrestres y en el espacio exterior. El cambio de sistemas de RF hacia sistemas ópticos en el espacio libre implica una serie de ventajas clave que motiva la transición hacia estas tecnologías. La primera y gran ventaja de trabajar con frecuencias pertenecientes al espectro óptico es el aumento del ancho de banda disponible, ya que trabajar a alta frecuencia implica directamente un incremento en el ancho de banda. Además, la eficiencia en términos de potencia es incrementada, ya que, para un tamaño de antena fijo, la potencia de señal recivida es proporcional al inverso de la longitud de onda al cuadrado. De especial interés es el desarrollo de sistemas de comunicaciones ópticos que utilicen modulaciones complejas, lo que implica una mayor eficiencia espectral y una mayor robustez contra efectos perniciosos introducidos por el canal. La detección coherente es una avanzada técnica que permite un aumento en la eficiencia espectral y maximiza la eficiencia de la potencia recibida. Esto es debido a que los simbolos son demodulados utilizando las señales en fase y cuadratura, aumentando los grados de libertad del sistema. En este contexto, los efectos de la atmósfera sobre las comunicaciones ópticas coherentes deben ser analizadas en detalle. Las turbulencias atmosféricas distorsionan el frente de onda y son responsables del deterioro de la tasa de error en las comunicaciones ópticas en el espacio libre. El uso de óptica adaptativa para mitigar los efectos de turbulencia atmosphérica abre una ventana a la implementación de la próxima generación de sistemas de comunicaciones, basados en tecnologías coherentes. En este trabajo se describe la implementación de un sistema completo de comunicaciones ópticas coherentes utilizando una modulación coherente (QPSK) y detección heterodina. Un sistema de óptica adaptativa y algoritmos de procesado de señal son implementados con el objetivo de mitigar los diferentes efectos introducidos por el canal. Por otro lado, un nuevo método para generar frentes de onda distorsionados por el canal atmosférico es desarrollado y su eficiencia es analizada. Este método se basa en el uso de holografía binaria generada por computador (BCGH) junto con un dispositivo de modulación óptica binaria de bajo coste (DLP). El funcionamiento del sistema completo es verificado y su eficiencia, en términos de tasa de error, son analizados. La eficiencia obtenida experimentalmente es comparada contra los modelos teóricos propuestos en la literatura. La viabilidad del uso de óptica adaptativa para mitigar efectos en sistemas ópticos coherentes es experimentalmente demostrada.
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Zimmermann, Kai [Verfasser]. "Experiments towards optical nuclear spectroscopy with thorium-229 / Kai Zimmermann." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover, 2010. http://d-nb.info/1008510548/34.
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Lambrecht, Alexander [Verfasser], and Tobias [Akademischer Betreuer] Schätz. "Optical ion trapping with regard to ultracold atom-ion experiments." Freiburg : Universität, 2017. http://d-nb.info/1136567089/34.
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Leach, Jonathan G. A. "Optical vortices and their angular momentum : new experiments and techniques." Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425159.
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Milner, Robert George. "Scanning near field optical microscopy : aperture experiments and apertureless theory." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620218.
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Afonina, Veronika Semenovna. "Optical studies of diatomic molecules at extreme conditions." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33136.
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The formidable progress achieved in the research at extreme conditions led to important discoveries of many unusual and interesting physical and chemical phenomena. Materials with high compressibility were and still are of particular interest due to a significant reduction of volume which could result in unexpected changes of bonding and/or electronic properties. Among highly compressible materials simple diatomic molecules such as H2, N2, and O2 are particularly interesting because they form new types of solids at high pressure. Hydrogen, being the most abundant element in the universe, possesses simple electronic structure, therefore, the study of hydrogen systems is of special interest. In the last three decades, there were subsequently explored and described several high-pressure phases of hydrogen up to 400 GPa. However, there is still a vast area of unexplained effects, which requires further analysis. The contributed work discusses Raman experiments in a wide pressure and temperature range where rotational and lattice phonon excitations have been measured in the Raman spectrum of solid H2 and D2 at 10, 77, 150 and 300 K from 2 to 180 GPa and up to 380 GPa at 300 K. Analysis of the Raman spectra allows to model how the rotational modes change with pressure and temperature and how the mass scaling laws evolve as the density increases in both hydrogen and deuterium. Comparison of vibrational frequencies of the isotopes appears to be extremely useful for estimation of equivalent pressures for both isotopes. Nitrogen and oxygen are archetypal elements possessing unique features such as extremely strong triple bond in case of N2 and magnetic moment in O2 . Both N2 and O2 exhibit rich polymorphism, with additional phases of O2 derived from its electronic and magnetic properties. N2 /O2 mixtures (for example, 20.9% O2 and 78% N2 mixture is air that we breathe) have been studied up to 12 GPa at 300 K experimentally and explored up to 500 GPa at 0 K theoretically. In the current project, N2 /O2 molecular systems are examined at 300 K up to 150 GPa. Rich polymorphism is observed, with seven phases exhibiting drastically different Raman spectra for concentrations below 45% of O2 and a more stable area with three phases in the concentration range from 45% to 80% of oxygen at pressures above 12 GPa. Moreover, characteristic Raman spectra obtained for the mix with 25% O2 after laser heating to approximately 2000 K at 25 and 96 GPa reveals pronounced peaks indicating the potential formation of new compounds.
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Tikan, Alexey. "Integrable turbulence in optical fiber experiments : from local dynamics to statistics." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R046/document.
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Ce travail est dédié à l’étude de l’origine des phénomènes statistiques récemment observés dans le cadre de la turbulence intégrable. Les études expérimentales et numériques de la propagation d’ondes partiellement cohérentes dans les systèmes décrits par l’équation de Schrödinger non linéaire à une dimension ont révélé un écart par rapport à la distribution gaussienne. Les régimes de propagation focalisant et défocalisant présentent un comportement qualitativement différent: la probabilité que des événements extrêmes apparaissent dans le cas focalisant est supérieure à la loi normale, alors que dans le régime défocalisant, elle y est inférieure. Nous avons réalisé des expériences d’optique bien décrites par l'équation de Schrödinger non linéaire 1-D afin d'étudier ce problème. Nous avons construit deux outils de mesure nouveaux et complémentaires. En utilisant ces outils, nous avons réalisé une observation directe des structures cohérentes qui apparaissent à différents stades de la propagation dans les deux régimes. En fournissant une analyse de ces structures, nous avons déterminé les mécanismes dominants dans les régimes focalisant et défocalisant. Dans le régime focalisant, nous avons mis en évidence le caractère universel de structures voisines des solitons de Peregrine et établi un lien avec un résultat mathématique rigoureux obtenu dans le régime semi-classique. Dans le régime défocalisant, nous avons montré que le mécanisme d'interférence non linéaire entre impulsions voisines définit l'évolution des conditions initiales partiellement cohérentes. Nous avons proposé un modèle simplifié qui explique la présence des différentes échelles dans les données enregistréesThis work is dedicated to the investigation of the origin of statistical phenomena recently observed in the framework of integrable turbulence. Namely, experimental and numerical studies of the partially-coherent waves propagation in 1-D Nonlinear Schrödinger equation systems revealed a deviation from the Gaussian statistics. Focusing and defocusing regimes of propagation demonstrated qualitatively different behaviour: the probability of extreme events to appear in the focusing case is higher than it is predicted by normal law, while in defocusing it is lower. We provided optical experiments well described by the 1-D Nonlinear Schrödinger equation in order to investigate this problem. We built two novel and complementary ultrafast measurement tools. Employing these tools we provided direct observation of coherent structures which appear at different stages of the propagation in both regimes. Providing analysis of these structures, we determined dominating mechanisms in both focusing and defocusing regimes. In the focusing regime, we discovered the universal appearance of Peregrine soliton-like structures and made a link with the rigorous mathematical result obtained in the semi-classical regime. In the defocusing case, we showed that the mechanism of nonlinear interference of neighbour pulse-like structures defines the evolution of the partially-coherent initial conditions. We considered a simplified model which explained the presence of different scales in the recorded data
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Talavera, Daniel J. (Daniel Joseph) 1980. "On-line laboratory for remote polymer crystallization experiments using optical microscopy." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/16975.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 88-89).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
This thesis discusses the architecture of an on-line optical microscopy laboratory, or iLab, in which students remotely conduct and analyze polymer crystallization experiments using a polarized light microscope under controlled temperature conditions. The Polymer Crystallization iLab involves melting a polymer sample and subsequently cooling it down to a temperature below its melting point in order to study isothermal crystallization phenomena. By analyzing the rates of nucleation and crystallite growth, students can characterize the kinetics of crystallization. As melting the polymer erases any prior history of the sample, the experiment can be repeated numerous times without requiring intervention in the laboratory. The architecture was designed with the goal of replicating the real laboratory experience to the maximum extent possible. Streaming temperature data and images from the microscope are sent to a Java applet, allowing the student to view and interact with the experimental apparatus in real time. The Java applet client runs on any conventional web browser and provides considerable latitude to students conducting the experiment, while ensuring proper safeguards. Students can record and save images and related data to a server to perform analysis at a later date. The analysis can either be conducted remotely on the server or the images can be downloaded to the user's computer for local analysis.
by Daniel J. Talavera.
M.Eng.
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Knust, Sebastian [Verfasser]. "Optical tweezers for DNA translocation and cell elasticity experiments / Sebastian Knust." Bielefeld : Universitätsbibliothek Bielefeld, 2020. http://d-nb.info/1213025605/34.
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Hawn, David Phillip. "The Effects of High Temperature and Nuclear Radiation on the Optical Transmission of Silica Optical Fibers." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345066048.
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Biasi, Stefano. "Light propagation in confined photonic structures: modeling and experiments." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/258037.
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This thesis explored fundamental concepts of linear optics focusing on the modal interaction within waveguide/microresonator systems. In addition, it investigated a nonlinear process of stimulated degenerate four-wave mixing in a channel waveguide exploiting the analogy between photons and cold boson atoms. The backscattering phenomenon due to the surface wall roughness of a microresonator is addressed by adding to the usual conservative (Hermitian) coupling coefficient, a dissipative (non-Hermitian) term. This allows explaining the experimental measurements of a multimodal microresonator, which exhibits an asymmetrical resonance splitting characterized by a difference in the peak depths of the transmission spectra. It is shown theoretically, numerically and experimentally that the stochastic nature of the roughness along with the inter-modal dissipative coupling could give rise to a different exchange of energy between the co-propagating and the counter-propagating mode. The unbalanced exchange of energy between the two modes with opposite angular momenta can generate a different reflection by swapping the injection of the light between the input and the output ports. This effect lies at the heart of the realization of an unidirectional reflection device and it finds an explanation in the physics of the exceptional points. The realization of an optical setup based on a Mach-Zehnder interferometer, which exploits some particular techniques of data acquisition, allows obtaining a full knowledge of the complex electric field of a propagating mode. In this way, the spectrum of a wedge microresonator vertically coupled to a bus waveguide is explained using analysis methods based on parametric phasors and inverse complex representations. In addition, the energy exchange between the co-propagating and counter-propagating modes is studied from a temporal point of view by extrapolating a simple model based on the Green function. In particular, it is discussed the analytical temporal response of a microring resonator excited through a bus waveguide by an optical rectangular pulse. Here, it is shown theoretically and experimentally, how the temporal response leads to the characterization of the coupling regime simply from the knowledge of the electric field intensity.
In this thesis, the isomorphism between the Schroedinger’s equation and the Helmholtz wave equation is analyzed in the nonlinear case. Considering a bulk nonlinear medium of the Kerr type, the complex amplitude of the optical field is a slowly varying function of space and time, which satisfies a nonlinear Schroedinger equation. The well-known nonlinear optical phenomenon of stimulated degenerate four wave mixing is reformulated in the language of the Bogoliubov theory. This parallelism between photons and cold atoms allows showing that the phase of the signal assumes a peculiar sound-like dispersion under proper assumptions.
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Rouxel, Jérémy. "A rigorous multipolar framework for nanoparticles optical properties description : theory and experiments." Thesis, Troyes, 2015. http://www.theses.fr/2015TROY0013/document.
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Les propriétés optiques linéaires et non-linéaires de nanoparticules métalliques de tailles non-négligeables comparées à celles des longueurs d’onde excitatrices sont étudiées dans cette thèse. Les informations issues de la symétrie sont mises en avant afin de décrire des nanoparticules appartenant à des groupes ponctuels. Pour cela, un formalisme totalement irréductible est mis en place afin de prendre en compte l’extension spatiale des objets étudiés. Dans ce formalisme, le tenseur de réponse non-linéaire possède un nombre fini de valeurs significatives reliant les composantes multipolaires des champs incidents et sortants. Ce formalisme est alors appliqué analytiquement à l’étude de la réponse non- linéaire du second ordre de nano-étoiles d’or en interprétant des mesures de SHG résolue en polarisation. Finalement, des expériences de spectroscopies multidimensionnelles sont utilisées dans le but de connecter les propriétés spatiales et les propriétés spectrales de ces objets. L’introduction de modes propres définis par la symétrie des objets permet encore une fois de donner un sens physique aux comportements électroniques mis en jeuUsing metallic nanoparticles with a threefold symmetry thorough the study, the impact of the symmetry on the nonlinear properties is investigated. Interpretations of polarization-resolved SHG experiments indicate the importance of multipolar resonances, in particular quadrupole and octupole, to explain the strong values of the nonlinear susceptibilities in such systems. A fully irreducible formalism is then developed to treat extended objects like nanoparticles. In this formalism, the nonlinear response tensor is a discrete set of values easily constrained by symmetries instead of a field. This formalism permits to describe simply linear and nonlinear optical response from nanoparticles. Finally, time-domain experiments are conducted with the aim to connect spatial and spectral properties. These experiments allow to interpret the spectra in terms of eigenmodes
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Fernandez, Angel. "Experiments for Laser Beam Propagation through Optical Turbulence : Development, Analysis and Applications." Thesis, Angers, 2016. http://www.theses.fr/2016ANGE0060/document.
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La turbulence atmosphérique générée par une différence de température entre le sol et l'atmosphère, provoque des effets sur les ondes optiques et présente un grand intérêt scientifique depuis de nombreuses années. Les distorsions du front d'onde optique induites par le résultat de la turbulence atmosphérique génèrent un étalement du faisceau au-delà de celles dues à la diffraction pure, à des variations aléatoires de la position du centre de gravité du faisceau, et à une répartition aléatoire de l'énergie du faisceau qui conduit à des fluctuations de l’irradiance.Ces effets ont des conséquences sur les communications optiques en espace libre (OFS), la désignation de cible, le LiDAR hyper spectral, et d'autres applications qui nécessitent la transmission d'ondes optiques dans l'atmosphère sur une grande portée.Tout au long de cette thèse, nous introduisons le concept général de la turbulence, en se concentrant sur la turbulence atmosphérique. Diverses expériences ont été réalisées, par exemple, la propagation de deux faisceaux parallèles dans les conditions de l'optique géométrique pour l'étude des paramètres de turbulence optiques. La même configuration optique a été utilisé pour étudier la meilleure fréquence d'échantillonnage pour la turbulence optique. En outre, nous avons indirectement mesuré l'évapotranspiration de couverts végétaux, pour laquelle nous tenons compte des fluctuations de l'indice de réfraction de la turbulence à travers les variations d’intensités du faisceau laser. Enfin, certaines expériences qui considèrent de nouvelles formes spatiale ou spectrale du faisceau ont également été développées, telles que le saut de mode et un super continuum spectral respectivement, montrant une réduction expérimentale des fluctuations de l'irradiance induite par la turbulence. Ces faisceaux ont une meilleure performance comme émetteur d'informations pour la communication optique en espace libreAtmospheric turbulence, generated by a differential temperature between the Earth's surface and the atmosphere, causes effects on optical waves that have been of great interest to scientists for many years. Wave front distortions in the optical wave induced by atmospheric turbulence result in a spreading of the beam beyond that due to pure diffraction, random variations of the position of the beam centroid, and a random redistribution of the beam energy within a cross section of the beam leading to irradiance fluctuations. Those effects have far-reaching consequences on astronomical imaging, free space optics (FSO) communications, remote sensing, laser satellite communication, astronomical imaging, adaptive optics, target designation, hyperspectral LiDAR, and other applications that require the transmission of optical waves through the atmosphere. Throughout this thesis, we introduce a globally concept of turbulence, focusing in atmospheric turbulence.Diverse experiments have been carried out, for instance, the propagation of two parallel thin beams under geometrical optics condition for studying the parameters of optical turbulence, and besides, the same optical configuration was used to investigate the best sampling rate for optical turbulence. Furthermore, we have measured evapotranspiration by remote sensing, in which we have heeded the fluctuations of the refractive index through the intensities of the turbulence. Finally, experiments which involve a new beam are also developed, such as phase-flipped Gaussian beam. This beam shows an experimental reduction on its irradiance fluctuations induced by the turbulence, which means that it has a high performance in optical communications. The experimental reduction aforementioned is proved through the comparison with the theory developed
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Bräunig, Philippe H. M. [Verfasser], and Markus [Akademischer Betreuer] Oberthaler. "Atom Optical Tools for Antimatter Experiments / Philippe H. M. Bräunig ; Betreuer: Markus Oberthaler." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180301803/34.
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Bräunig, Philippe [Verfasser], and Markus [Akademischer Betreuer] Oberthaler. "Atom Optical Tools for Antimatter Experiments / Philippe H. M. Bräunig ; Betreuer: Markus Oberthaler." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-180444.
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Worth, Bradley William II. "Experiments on Zeeman-based Electromagnetically Induced Transparency and Optical Sensing in Turbid Media." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1388069839.
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Enderlein, Martin [Verfasser], and Tobias [Akademischer Betreuer] Schätz. "Optical ion trapping for (scalable) quantum simulations and ultracold chemistry experiments = Optisches Ionenfangen für (skalierbare) Quantensimulationen und Ultrakalte-Chemie-Experimente." Freiburg : Universität, 2013. http://d-nb.info/1123474303/34.
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Santos, Sofia Raquel Gonçalves dos. "Suspended sediment measurements on laboratory experiments." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/17341.
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Mestrado em Engenharia CivilThe sediment transport processes in rivers and coastal zones are characterized by two types of transport: bed-load and suspension. The quantification of this transport is important, in the evaluation of the shoreline and rivers evolution in order to protect areas that could be in danger of erosion when extreme meteorological phenomenon’s happen. How to measure the suspended sediment concentration has been subject of many discussions during the last years. There are several methods to quantify it numerically, although all of them exhibit uncertainties in the results. This work, performed in the Laboratori d’Enginyeria Marítima (LIM) of the Universitat Politècnica de Catalunya (UPC), has as goal to understand why the results obtained from the Optical Backscatter Sensors (OBS) and the Transverse Suction System (TSS) in SINBAD project were distant. To do it, after perform three hundred and twenty nine tests, the experimental and calculation procedures to obtain the best OBS calibration curve were described. Then, the concentrations from OBS and TSS were compared with the real concentrations. In the end, the functionalities of the equipment’s involved in the calibration set-up, OBS applicability and trapping efficiency of TSS, were verified. The results showed that, an accurate fit of OBS data is obtained when the curve is divided in sections depending on the suspended sediment concentration, with different behaviours and fitted differently. This equipment was considered the most accurate, up to concentrations bellow the saturation situation of the sensor.
Os processos de transporte sedimentar nos rios e zonas costeiras caracterizam-se por dois tipos de transporte: pelo fundo ou em suspensão. A quantificação deste transporte é importante, na avaliação da evolução da linha de costa e do leito dos rios, com vista a proteger zonas que possam estar em perigo de erosão na eminência de fenómenos meteorológicos extremos. A medição da concentração de sedimentos em suspensão tem sido, ao longo dos últimos anos, objeto de estudo por vários investigadores. Existem vários métodos para estimar esta grandeza no entanto, ainda apresentam muitas incertezas nos resultados. Esta dissertação, desenvolvida no Laboratório de Engenharia Marítima (LIM) da Universidade Politécnica da Catalunha (UPC), tem como objetivo a verificação do distanciamento dos resultados entre o Optical Backscatter Sensor (OBS) e o Transverse Suction System (TSS) no projeto SINBAD. Para isso, e após realizar 329 testes, foram descritos o procedimento experimental e de cálculo para obter a melhor reta de calibração de um OBS. Seguidamente, as concentrações obtidas com o OBS e com o TSS foram comparadas com as concentrações de sedimentos reais e no final foram verificados parâmetros relacionados com a funcionalidade dos equipamentos utilizados na calibração, a aplicabilidade do OBS e a eficiência do TSS. Os resultados mostraram que, a curva de calibração mais exata de um OBS obtém-se quando os dados são divididos em secções em função da concentração de sedimentos, com diferentes comportamentos, e tratadas separadamente. Este equipamento foi considerado o mais exato, até concentrações em que o sensor não está saturado.
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Petruck, V. G., S. M. Kvaternyuk, A. P. Ivanov, V. V. Barun, B. A. Bolyukh, D. B. Bolyukh, В. Г. Петрук, et al. "Non-Invasive Optical Diagnostics of Pigment Formations of Human Skin." Thesis, Technical University of Moldova, 2014. http://ir.lib.vntu.edu.ua/handle/123456789/942.
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Measurement results of spectral reflection characteristics under multiple light scattering by
healthy skin and by skin regions with melanoma or nevus are given. Experimental setup that operates on the
base of the Taylor method is described. It is shown that the diffuse reflectance R of melanoma skin is lower at
all the studied wavelengths from the range about 450 to 1000 nm as compared with that of healthy and
benign nevus skin. This conclusion is confirmed by a large number of measurements of big groups of
different persons. The gathered data demonstrated an opportunity to differ malignant and healthy or benign
formations, while operating in the visible to near IR range. Examples of such a differentiation at several
wavelengths are given
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Mellish, Angela Susan, and n/a. "Experiments with Bose-Einstein condensates in optical lattices and cold collisions of ultracold atoms." University of Otago. Department of Physics, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070126.100723.
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The experimental realisation of Bose-Einstein condensation in 1995 opened up a wealth of opportunities for probing quantum states of matter. The development of many tools used to manipulate such ultracold samples and the rapid progress on understanding these systems will ultimately lead to great technological advances. The work described in this thesis contributes to this worldwide effort and here we present experiments which investigate the properties and behaviour of ultracold atoms.
In the first experiments presented here, we have studied features of Bose-Einstein condensates loaded into an optical lattice formed by the interference of two laser beams. By altering the phase of the lattice at the Bragg condition, we investigate the effect of the phase shift on the dressed-atom states. We find that by applying a +(-)[pi]/2 phase shift after a [pi]/2 (3[pi]/2) lattice pulse, we are able to quickly and precisely load the ground and first excited eigenstates of the lattice. In another experiment, we use a periodically pulsed stationary optical lattice and a tightly-confined Bose-Einstein condensate to investigate the nonlinear kicked harmonic oscillator at quantum anti-resonance. We observe periodic behaviour in the energy of the condensate, however we show that the nonlinearity is not strong enough to enter the predicted chaotic regime. In addition, the amplitude of the energy oscillations damps to an average value and we relate this to dephasing of the coupling across the finite momentum width of the condensate.
In the second series of experiments, we use a double-well magnetic collider to investigate cold collisions between ultracold atoms. By creating two ultracold clouds in a double-well magnetic trap and then transforming the trap to a single well, we accelerate the clouds together to initiate a collision between them. We describe in detail the analysis method that we use to extract the partial-wave phase shifts from the matter-wave interference patterns associated with the scattered atoms. We then implement a two-photon pulse, which is applied prior to the collision to convert one of the clouds to a different spin state. This enables the study of scattering between distinguishable states which exhibited anti-symmetric p-wave scattering via the interference with the s- and d-waves previously observed for indistinguishable states. We find the position of the d-wave shape resonance and compare our data to a coupled-channels model.
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Zhong, Shan. "AN IMPROVED LASER COOLING AND ATOM TRAPPING SETUP FOR OPTICAL LATTICE AND RATCHET EXPERIMENTS." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1438900984.
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Tavernarakis, Alexandros. "Design, realization and stabilization of quantum optical injection system for ultra-sensitive quantum opotomechanics experiments." Paris 6, 2012. http://www.theses.fr/2012PA066599.
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L’optomécanique en cavité, l’ étude de l’interaction entre le mode d’une cavité optique et un mode mécanique d’un résonateur, a eu une évolution impressionnante depuis dix ans et elle est devenue un nouveau champ de recherche, réunissant la physique de la matière condensée et l’optique. Un des objectifs majeurs de cette discipline est de tester et étudier la mécanique quantique en utilisant des systèmes macroscopiques. Parmi les problèmes les plus fondamentaux que la communauté aborde est la question des limites quantiques de la mesure de position. La mécanique quantique prédit que toute mesure s’accompagne d’une action en retour, ce qui perturbe l’ état du système muser ́e. En outre, il devrait être conjugué avec le bruit quantique de l’appareil de mesure (le bruit de mesure) utilisé pour sonder le système. La sensibilité e optimale est atteinte lorsque la mesure et le bruit abréaction sont identiques, une situation qui peut être assimilé à l’acceptation de l’inégalité de Heisenberg pour l’appareil de mesure. En optomécanique, le mode d’une cavité optique est utilisé comme un appareil de mesure de la position d’un résonateur mécanique qui est piloté par la pression de radiation et qui devrait être responsable pour l’action en retour de la mesure. Cependant, cette action en retour n’a jamais été observe à ce jour, alors qu’il reste une étape décisive vers la compréhension des processus du mesure quantique. Nous décrivons dans ce manuscrit l’étude des effets de la pression de radiation. Nous introduisons le système optomécanique que nous avons développé qui consiste a un résonateur mécanique plan-convexe de taille de quelques cm présentant un très haut facteur de qualité (~106) intégré dans une cavité Fabry-Pérot de très grande finesse (≃ 300 000). Nous pressentons deux résultats importants que nous avons obtenus avec ce système. Tout d’abord, nous avons rapporté la première observation directe de la pression de radiation en temps réel, basée sur l’ ́établissement pompe-sonde corrélations. Nous avons également démontré pour la première fois des effets non linéaires dû à l’action en retour lies l’amélioration substantielle de la sensibilité de la mesure de position. Nous expliquons pourquoi la démonstration de l’action en retour quantique nécessite une ultra-haute stabilité du mode optique. Nous presentons les modifications importantes apportées la configuration expérimentale précédente, notamment sur la source laser, la détection et la stabilisation de l' expérience. Nous décrivons ensuite une nouvelle technique de détection optomécanique fournissant une mesure indépendante du désaccord de la cavité. Enfin, nous pressentons une expérience de validation de principe permettant d’extraire des corrélations quantiques optomécaniques à la température ambianteCavity Optomechanics, that is the study of the interaction between an optical cavity mode and a mechanical degree of freedom, has known impressive evolution over the past decade, to become a new field at the union of condensed matter physics and optics. One of the major goals of this discipline is to test and study quantum mechanics using macroscopic systems. Among the most fundamental problems the community aims to address is the question of the quantum limits in position measurement. Quantum mechanics predicts that any measurement comes along with a backaction, which perturbs the state of the measured system. Moreover, it is expected to be conjugated with the quantum noise of the measurement apparatus (called measurement noise) used to probe the system. The optimal sensitivity is reached whenever both the measurement and the backaction noise are identical, a situation which can be assimilated to the acceptance of Heisenberg's inequality for the measurement apparatus. In cavity optomechanics, the mode of an optical cavity is used as a measurement apparatus of the position of a mechanical resonator which is expected to be responsible for the back-action imprecision. However, this so-called radiation pressure quantum back-action has never been observed to date, while it remains a decisive step towards understanding quantum measurement processes. We describe in this manuscript the study of radiation pressure effects in cavity optomechanics. We introduce the optomechanical system we have developed, which consists in a cm-scale ultra high Q (~ 106 ) plano-convex mechanical resonator incorporated into a ultra-high finesse (~ 300 000) Fabry-Pérot cavity. We present two important results we obtained with this system. First, we were able to report the first direct observation of radiation pressure in real-time, based on establishing pump-probe correlations. We were also able to demonstrate for the first time nonlinear backaction effects related to substantial improvement of position measurement sensitivity. We explain why demonstrating quantum back-action requires ultra-high stability of the optical mode. We present important changes made to the previous experimental setup, notably on the laser source, on the detection and the stabilization of the experiment. We then describe a new optomechanical detection technique providing an independent measurement of the cavity detuning. Finally, we present a proof-of-principle experiment allowing to extract quantum optomechanical correlations at room temperature
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Adamovich, Igor V. "Studies of nonequilibrium vibrational kinetics of carbon monoxide and nitric oxide in optical pumping experiments /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu148784730905197.
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Fung, Ho Ting. "A study of instrumental systematic effects due to quasi-optical components on CMB polarisation experiments." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/a-study-of-instrumental-systematic-effects-due-to-quasioptical-components-on-cmb-polarisation-experiments(0bef41e6-dd8c-4088-808d-826e8dfe939d).html.
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The new generation of astronomical instruments are not only in need of the highest sensitivity but require also well-controlled and known instrumental systematic effects. This is particularly relevant for projects dedicated to the study of the Cosmic Microwave background (CMB). Following the success of the Planck mission in providing the most detailed picture of the CMB temperature anisotropy to date, the next generation of CMB projects such as COrE (a potential future mission) and QUBIC (a ground based instrument)will be aiming to study the polarisation anisotropy of the CMB. However, the expectedB mode signal from the CMB is several orders of magnitude weaker than the temperature counterpart. Hence the calibration procedures will have to be more stringent than the ones that have been adopted for Planck, to get a proper detection of the primordialB mode signal. For instance, measurements for the receiver and optical systematic effects must be taken into consideration to get a proper reconstruction of the B modepower spectrum. This thesis is focused on the impact of real individual receiver and optical componentson the observation of the primordial B modes. To achieve this, several receiver and quasioptical components have been measured and modelled for their instrumental systematic effects. An analysis pipeline has also been developed, to assess the impact of such instrumental systematic effects on the observation of the primordial B modes. Using the results from the measurements and the analysis pipeline, the instrumental systematic effects that are of concern to the observation of primordial B modes have been identified. This is assuming that no effort has been made to mitigate such instrumental systematic effects.
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Valley, John Francis. "Nonlinear optical experiments in sodium vapor and comparison with Doppler-broadened two-level-atom theory." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184930.
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Two spectral regions of gain exist for a weak probe beam propagating through a medium of two-level-atoms pumped by a strong near-resonance field. Experimentally a cw ring-dye laser is used to explore this gain at the Na D₂ resonance in a vapor. Plane-wave calculations of probe-gain spectra which include the Doppler broadening inherent in a vapor agree well with experimental spectra obtained with a Fabry-Perot interferometer. Such two-beam-coupling gain might have applications as optical pre- or power amplifiers. The gain is also the primary step in four-wave-mixing. Mixing of the pump and sideband which experiences gain produces the medium polarization from which the fourth-wave arises. For phase-matched propagation the fourth-wave, which is at a frequency that experiences little or negative probe-gain (i.e., absorption), grows at nearly the same rate as the primary sideband. Together the two sidebands extract far more than twice as much energy from the pump than does the primary sideband acting alone. Experimentally four-wave-mixing which arises from noise at the gain-sideband-frequency is sometimes accompanied by conical emission at the fourth-wave sideband. Since this sideband is also seen on axis the explanation cannot be simply phase-matching. Simulations which include the full transverse nature of the experiment are currently running on a CRAY supercomputer. These simulations indicate that the radial variation of the medium index of refraction is responsible for conical emission.
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Kim, Soo Y. "Cold single atoms for cavity QED experiments." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26581.
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Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2009.Committee Chair: Chapman, Michael; Committee Member: Citrin, David; Committee Member: Kennedy, T. A. Brian; Committee Member: Kuzmich, Alexander; Committee Member: Raman, Chandra. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Tesche, Matthias. "Vertical profiling of aerosol optical properties with multiwavelength aerosol lidar during the Saharan Mineral Dust Experiments." Doctoral thesis, Universitätsbibliothek Leipzig, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-71257.
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Die vorliegende Arbeit beschäftigt sich mit der Auswertung und den Ergebnissen von Mehrwellenlängen–Polarisations–Ramanlidarmessungen, die im Rahmen des Saharastaubschließungsexperiments Saharan Mineral Dust Experiment (SAMUM) durchgeführt wurden. Das SAMUM–Projekt erstreckte sich über zwei Intensivmesszeiträume im Mai und Juni 2006 in Marokko (SAMUM–1) und im Januar und Februar 2008 auf den Kapverdischen Inseln (SAMUM–2). Desweiteren werden zusätzliche Lidarmessungen
besprochen, die im Mai und Juni 2008 auf den Kapverdischen Inseln durchgeführt wurden. Die geometrischen und optischen Eigenschaften der während dieser Experimente mit mehreren hochmodernen Lidargeräten beobachteten Mineralstaub- und Biomassenverbrennungsaerosolschichten werden anhand von Fallstudien und mehrwöchigen, höhenaufgelösten Mittelwerten beschrieben. Zudem werden Kalibrierungen und Korrekturen vorgestellt, die zur Qualitätssicherung der gewonnenen Messdaten durchgeführt wurden. Ein im Rahmen der Arbeit entwickeltes, auf quantitativen Messungen des linearen Partikeldepolarisationsverhältnisses basierendes Verfahren zur höhenaufgelösten Trennung der Anteile von Mineralstaub und Biomassenverbrennungsaerosol an den während SAMUM–2 gemessenen Rücktreu- und Extinktionsprofilen wird vorgestellt
und angewandt.
Die Auswertung der Mehrwellenlängenlidarmessungen der SAMUM–Kampagnen ermöglichte eine spektral aufgelöste Charakterisierung der optischen Eigenschaften von Saharastaubpartikeln. Besondere Aufmerksamkeit wurde auf die Bestimmung der intensiven Parameter Extinktions–zu–Rückstreuverhältnis (Lidarverhältnis), lineares
Partikeldepolarisationsverhältnis sowie Ångströmexponent der Rückstreu- und Extinktionskoeffizienten gelegt. Die im Rahmen von SAMUM bei den Wellenlängen 355, 532 und 1064 nm durchgeführten Lidarmessungen ergaben mittlere Lidarverhältnisse von 55±5 sr für reinen Saharastaub. Während SAMUM wurden außerdem erstmals quantitative Messergebnisse des linearen Partikeldepolarisationsverhältnisses von reinem Saharastaub
bei mehreren Wellenlängen gewonnen. Die mittleren Werte dieser Größe lagen bei 0.26±0.06 (355 und 1064 nm), 0.31±0.03 (532 nm) und 0.37±0.07 (710 nm).
Diese Erkenntnisse liefern wichtige Informationen für die Auswertung von Messungen mit weniger fortschrittlichen Lidargeräten. Die durch SAMUM gewonnenen Erkenntnisse der optischen Eigenschaften von Mineralstaub erlauben eine eindeutige Identifikation des Staubanteils in Aerosolschichten im Abluftbereich der Wüsten. Zudem wurden
Richtgrößen ermittelt, die zur Validierung von Modellen zur Beschreibung von Lichtstreuung an großen, nicht–kugelförmigen Teilchen verwendet werden können. Derartige Streumodelle werden für die Auswertung von Messungen der optischen Eigenschaften
von Mineralstaubpartikeln mit passiven Sensoren benötigt und befinden sich zur Zeit eher in einer frühen Entwicklungsphase.
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Yu, Shi Jing. "The study of field programmable gate array based servos in atomic, molecular and optical physics experiments." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61323.
Full textAbstract:
The use of Field Programmable Gate Array (FPGA) is becoming increasingly popular in new designs for instrumentation tools. Among them, the FPGA-based servo is emerging as a replacement for the traditional analog servo as a more versatile, automated and remotely controllable alternative. Despite the demonstration of FPGA servos for the control of lasers in the literature, the practical constraints of an FPGA servo have not yet been fully investigated. This work presents an open-source FPGA servo design that is capable of reaching a total signal latency of 200 ns including both conversion delay and computation delay. This work also investigates various limitations inherent in a digital implementation of a servo arising from the computation precision of an Infinite Impulse Response (IIR) filter and the effect that signal quantization has on the transfer function that a digital servo can implement. These technical details are not widely discussed, but are important both for the design and the operation of the FPGA servo. Applying the FPGA servo in an intensity stabilization application allows direct tests of these limitations. In particular, this work compares the performance of the FPGA servo and a high-performance commercial analog servo with a focus on key specifications including the closed-loop bandwidth, noise floor and the resolution of the transfer functions. For closed-loop control scenario with a bandwidth below 1 MHz, we achieve better performance with the FPGA servo than the analog servo through the use of more complex transfer functions including a Proportional and Integral Cubed (PI3) and a Proportional Integral and Integral (PII) with lag-lead.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Pollard, Mark Robert. "The development of novel force probes, high speed imaging and electronics to enhance optical trapping experiments." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544018.
Full text
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Edwards, Emily E. "Construction of apparatus and first experiments investigating dynamics of Bose-Einstein condensates in disordered optical lattices." College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9156.
Full textAbstract:
Thesis (Ph.D.) -- University of Maryland, College Park, 2009.Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Farré, Flaquer Arnau. "Momentum measurements of single-beam traps and quantitative holographic experiments: two sides of the same coin." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/83665.
Full textAbstract:
After an intense development of optical tweezers as a biophysical tool during the last decades, quantitative experiments in living cells have not found in this technique its best ally, due, in part, to the lack of a reliable method to measure forces in complex environments. The attempts to overcome this problem either require complicated in situ calibrations, which make their use impossible in the study of dynamic processes, or they are inaccurate. Using a different approach, Steven Smith at Carlos Bustamante’s lab at the University of Berkeley developed a method based on the direct measurement of the momentum change of the trapping beam. However, its diffusion has been modest mainly because it requires a counter-propagating optical trapping system, which is difficult to implement and combine with other techniques. Although it has not been used for this purpose yet, it seems a more suitable method for in vivo experiments since the measurement depends only on some properties of the sensor apparatus but not on the experiment itself.
On the other hand, the use of holographic optical tweezers in molecular biology experiments involving force and position measurements is still far from established. The existence of different effects associated to the use of spatial light modulators to create the optical traps has restricted their use.
In this thesis, I present the work that I carried out in the Optical Trapping Lab – Grup de Biofotònica at the University of Barcelona related to these two subjects. During these years, I have focused on the implementation of the force detection method based on the conservation of the light momentum in single-beam optical traps, and on the analysis of several aspects of holographic tweezers oriented to their use in quantitative experiments.
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Tzevelecos, Wassilis. "Contribution to Heat and Mass Transfer for Space Experiments." Doctoral thesis, Universite Libre de Bruxelles, 2018. https://dipot.ulb.ac.be/dspace/bitstream/2013/269864/6/contratWT.pdf.
Full textAbstract:
This manuscript has been realized in the frame of SELENE experiment research activities. SELENE is the ac-ronym of Self-rewetting fluids for ENErgy management and consists of a space project aiming to investigate heat and mass transfer phenomena in mono-groove configuration with self-rewetting fluids (SRFs). Self-rewetting fluids are mixture showing an anomalous trend of surface tension with temperature, an inversion of the surface tension slope after certain temperature. As consequence, when the minimum in surface ten-sion is crossed, surface tension gradient at the meniscus interface pulls the liquid towards the warmest region, preventing hot spots. This mechanism is completely spontaneous and has an interesting potential when applied to heat transfer applications as heat pipes (HPs). In HPs heat is removed by the liquid at the warmest region (the evaporator) and transported at the coldest zone (the condenser) by phase change; here, heat is removed by the pipe and dissipated outside through a radiator. To operate correctly, liquid is supplied to the evaporator by capillarity and the liquid vapour is allowed to flow back to condenser from a dedicated pipe region where liquid is not allowed. Vapour condensation releases at the condenser the heat to be dissipated. When SRFs are replacing working fluid in HP applications and temperatures are higher than the characteristic minimum in surface tension, capillary force is assisted by inverse Marangoni flow at the vapour-liquid interface.Since heat pipe performances are related to liquid supplied at the evaporator, in order to compare SRFs and not SRFs working fluids, it is needed to split the contribution of Marangoni and capillary force in the liquid flow. Marangoni effect is related to surface tension gradient that, in a mixture as SRF, is dependent on temperature and local composition at the liquid interface. For all these reasons, SELENE is designed to be the link between scientific research on HPs and heat transfer applications using SRFs. SELENE consists of a mono-groove with trapezoidal section that can be considered as a “clump” of an Inner Grooved Heat Pipe (IGHP) and, in order to split capillary and Marangoni contribution, it is integrated dedicated tools providing the required data in terms of concentration and liquid meniscus shape. Experimental data are used to build a simplified thermo-soluto-fluido dynamic model describing the thermo-mechanic mechanisms between the liquid bulk and the vapour flow. In the manuscript here presented it has been carried on a technology development of the required diag-nostics for the SELENE space project. The diagnostics have been designed to work in microgravity condi-tions even if they are tested on ground. As concentration diagnostic, in the text are proposed several tech-niques and more interest is spent on the adaptation of I-VED (In vivo Embolic Detection) technology meas-uring fluid AC impedance to retrieve composition information; the technology is not yet mature to be inte-grated in SELENE but it presents interesting features to be investigated in microgravity conditions. As me-niscus reconstruction technique it is proposed a new and innovative technology developed in the frame of the presented thesis and it consists of a non-intrusive optical technique aiming to retrieve liquid meniscus shape (and so curvature) from a single visualization window mounted at the top of the SELENE breadboard.An analytical approach aiming to retrieve a simplified mathematical model of the transfer mechanisms is also provided in the text. The analytical analysis clearly shows the relations between the experimental measured data and the velocity profiles in the liquid and vapour regions. In addition, since in SELENE exper-iment the heat conduction across the groove itself is not negligible, in the text it is provided a semi-empirical thermal model based on the Multi Lumped Model (MLM) theory and able to retrieve local heat exchanged information along the pipe length. The model is used to compare experiments with different working fluids at different operational regimes.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished