Teses / dissertações sobre o tema "Forces optiques"
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Moine, Olivier. "Modélisation de forces optiques". Aix-Marseille 3, 2005. http://www.theses.fr/2005AIX30055.
Texto completo da fonteThis work deals with theoretical modeling of optical forces on micro-meter scale objects using exact electromagnetic calculations. In the first part, we derive and review the two approximate techniques commonly used to calculate optic in the two extreme size domains : the Rayleigh approximation for dealing with particles considerably smaller than the wavelength, [lambda] , of the trapping radiation, and the geometric optics approximation which applies to particles much larger than [lambda]. We then illustrate the limits of these approximate techniques via a comparison with the exact calculations that we have developed. In the second part, we consider optical traps containing multiple particles. For such studies we couple our exact calculation technique with exact solutions of the multi-scattering equations in order to evaluate the optically induced forces that appear between particles in multiparticle traps. Most of our applications to date concern homogeneous spherical trapped particles, and a the third part studies the extension to more general particles like coated spheres which can be used to model biological organites like cells. The last part concerns the applications of theoretical modeling to the rapidly developing field of optical tweezers for mico-meter scale manipulation
Nouho, Ali Ali. "Confinement électromagnétique sub-longueur d'onde et couplage entre nano-structures photoniques : Calcul de forces et de moments optiques". Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD057.
Texto completo da fonteThis thesis work is a contribution to the numerical modeling of new optical devices based on photonic nano-structures such as photonic crystals, plasmonic nano-antennas or enhanced-transmission metamaterials. The objective is to enhance the light confinement in these structures to further use it as a source of trapping to manipulate resonant or non-resonant metallo-dielectric particles.The first part is devoted to the modeling of the local electrostatic field generated by the application of a DC voltage across two electrodes, on a nano-structured dielectric acting as an active material in electro-optical modulators. The idea is to enhance the local electrostatic and optical fields in the material to induce a more substantial modification of its local index, thus leading to an amplification of its nonlinear effects. In particular, we have shown that by optimizing the geometrical shape of the electrodes, the local electrostatic field can be further exalted inside the material leading to exacerbate the electro-optical effect by a factor 6.The second part concerns the modeling of optical forces and moments acting in nanostructures by the Finite Difference Time Domain Method (FDTD). After presenting the principle of modeling of the optical forces and torques, a specific application is considered to study the translational and rotational motions of a dielectric disk placed at the output side of a quarter-wave plate made of metamaterial formed of coaxial apertures with elliptical section engraved in an opaque metal film. On the other hand, we show how an optical tweezer based on Diabolo nano-antennas can be used to sort and arrange dielectric nanoparticles according to their size by tuning the wavelength of the incident beam.The third and last part is dedicated to the study of optical trapping of metallo-dielectric nano-particles and the coupling between different optical nano-resonators according to the distance separating them and according to their natures. A detailed study is presented to analyze and understand the properties (scattering, absorption, extinction,) of these nano-resonators at the sub-wavelength scale. An application has been processed on the trapping of dielectric nano-particles by an optical nano-tweezers based on a photonic crystal coupled to a Bowtie nano-antenna
Desmarchelier, Rudy. "Analyses des forces photo-induites par le laser femtoseconde dans les verres à base de silice". Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01064070.
Texto completo da fonteStuder, Michel Studer Michel. "Etude des forces pontantes dans un matériau composite à l'aide de réseaux de Bragg dans des fibres optiques /". [S.l.] : [s.n.], 2001. http://library.epfl.ch/theses/?nr=2451.
Texto completo da fonteLecarme, Olivier. "Propriétés optiques de colloïdes assemblés : plasmonique et confinement diélectrique". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00673254.
Texto completo da fonteBercy, Mathilde. "Les structures secondaires dans l'ARN : une étude par mesure de forces sur molécules uniques". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066718/document.
Texto completo da fonteTraditionally, RNA has been considered as a mere intermediate between DNA, keeper of the genetic information, and proteins, which assume cells self-sustenance. With the discoveries of the transfert RNA in the 70s, and of the ribozymes in the 80s, RNA took on both roles: it can store information in its linear sequence, and tridimensional structuration enables catalytic functions. Since then, numerous roles devoted to RNA have been discovered, particularly for gene expression regulation. Most of these functions rely on tridimensional structuration of single stranded RNA. In this work, we used an optical tweezers setup to study several aspects of RNA structuration by single molecule force measurement. In a first part, we compared the dynamic behaviour of a model secondary structure made of either RNA or DNA, the hairpin. Then we considered the interaction of a secondary structure with a protein, the RNA helicase DbpA. Finally, within a wider study of ribosome assembly, we worked on the development of a new method to study tridimensional structuration. This method relies on the overstretching of a hybrid ribosomal RNA / DNA molecule
Medeiros, Luiz Henrique Alves de. "Méthodes de calcul de forces électromagnétiques : application au calcul des distributions de forces sur les aimants permanents". Grenoble INPG, 1998. http://www.theses.fr/1998INPG0095.
Texto completo da fonteCastin, Yvan. "Les limites du refroidissement laser dans les mélasses optiques à une dimension". Phd thesis, Université Pierre et Marie Curie - Paris VI, 1992. http://tel.archives-ouvertes.fr/tel-00011882.
Texto completo da fonteDebbichi, Lamjed. "Etude ab-initio des propriétés électroniques, optiques et du transport électronique dans les nanotubes de carbone". Strasbourg, 2010. http://www.theses.fr/2010STRA6231.
Texto completo da fonteThe objective of this work is to understand the effects of impurities on the electronic and transport properties of single wall carbon nanotubes. In the first part, we studied the effect of substitutional doping by boron, nitrogen or silicon atoms on the electronic structure of carbon nanotubes for different diameters in order to determine the chemical reactivity as a function of the nanotube curvature. We then studied the impurity distribution as a function of the nanotube chirality and the behavior of the optical spectra as a function of the diameter and the chirality of the nanotubes and as a function of the impurity distribution. In a second part, we used the nonequilibrium Green’s function to understand the electronic transport of carbon nanotubes. This is to calculate the electric conductance of a single nanotube in which an organic molecule is either inserted or adsorbed on its surface. To determine the adsorption of the molecule we calculated the total energy, taking into account the dispersive forces of van der Waals. We also studied the effect of spin polarized chemical bonding at the interface of the Fe(001)-nanotube direct junctions on the electronic transport of zigzag and armchair nanotubes of different sizes
Rodriguez-Otazo, Mariela. "Réalisation de pinces optiques pour la manipulation de nano et micro objets individuels d'intérêt chimique ou biologique". Paris 11, 2008. http://www.theses.fr/2008PA112099.
Texto completo da fonteWe built an experiment of optical tweezers based on the use of an inverted optical microscope. Two classes of micro objects were studied : 1 - spherical or roughly spherical colloidal particles, either homogeneous such as colloids of pure silica elaborated through a sol-gel method or commercial latex balls, or inhomogeneous such as composite particles made up of a metal gold core embedded in a silica shell. 2 - micro-single crystals of a fluorescent organic molecule presenting a nonspherical, parallelepipedic form. Our study showed an effective trapping even on the smallest particles containing a gold core. For the hybrid gold-silica nanoparticles, the elastic constant of the optical trap measured in experiments is stronger than for the silica nanoparticles with a similar diameter. This result is in agreement with a simple model based on the increase in polarizability of the particle due to the presence of the gold core. The influence of the polarization of the light was studied and we discussed the choice of the detector of position. The organic microcrystals are directed so that their long axis is in the axial direction of the trapping beam; the short axis follows the direction of the linear polarization of the beam. In circular or elliptic polarization, the crystals are put spontaneously in rotation with high speed up to 500 turns per second. It is the ¯rst time that such a result is deferred for particles of the size of our crystals. Another surprising result is that when the incident power increases, the rotation speed also increases as expected but after the passage by a maximum, whereas the power continues growing, the rotation speed decreases until complete stop of rotation, and this evolution is not reversible ! The thesis presented is a thesis carried out within a framework of cotutelle between the University Paris 11 and the Higher Institute of Science and Advanced Technologies - Havana University in Cuba
Lounis, Brahim. "Atomes refroidis par laser : de la mélasse au cristal optique". Phd thesis, Université Paris Sud - Paris XI, 1993. http://tel.archives-ouvertes.fr/tel-00011889.
Texto completo da fonteCourtois, Jean-Yves. "Spectroscopie Raman et Rayleigh stimulie d'atomes refroidis par laser : dynamique des mélasses optiques unidimensionnelles". Phd thesis, Ecole Polytechnique X, 1993. http://tel.archives-ouvertes.fr/tel-00011887.
Texto completo da fonteVexiau, Romain. "Dynamique et contrôle optique des molécules froides". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00783399.
Texto completo da fonteHorache, El-Houssine. "Corrélation optique multiplexe basée sur la modulation spatiale de cohérence d'une source à spectre large : application à la reconnaissance des formes". Marne-la-Vallée, 2001. http://www.theses.fr/2001MARN0107.
Texto completo da fonteBambardekar, Kapil. "Applying optical tweezers in vivo : A biophysical study of mechanical forces in Drosophila Melanogaster at the onset of gastrulation". Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4003/document.
Texto completo da fonteHere, an optical tweezers setup was developed on a pre-existing single-plane illumination (SPIM) setup. The cell-cell interface in embryonic epithelia could be trapped and manipulated directly with optical tweezers. The interaction of the interface with the trap was initially characterized at the end of cellularization where the tissue has minimal movements and actomyosin turnover. With a sinusoidal trap excursion, the interface amplitude was found to increase linearly with applied laser power as well as trap amplitude and time period. Furthermore, push and pull experiments on the interface responding to a stationary trap, provided another way to address the viscoelastic properties of the interface. The interface kinetics in stationary experiments could fit adequately to a passive viscoelastic model. This model also explained well the linear response to trap amplitude and time period, and formed the basis of estimating interface tension from its amplitude. Moreover, the propagation of the sinusoidal movement to neighbouring interfaces decayed rapidly with minimal phase lag in both experiments and the model. Having established a suitable regime of trapping conditions, where interface deflection is small and linear, the mechanical anisotropy of the epithelium was at the onset of gastrulation. The interface tension increased by 2-3 fold, exhibiting both apico-basal and dorso-ventral polarization of tension, concomitant with polarized accumulation of myosin. The role of myosin was established further through ROCK-inhibition. Perturbation of actin also decreased the interface tension. My work provides a crucial insight into the mechanical behaviour of dynamic epithelia
Ravets, Sylvain. "Development of tools for quantum engineering using individual atoms : optical nanofibers and controlled Rydberg interactions". Thesis, Palaiseau, Institut d'optique théorique et appliquée, 2014. http://www.theses.fr/2014IOTA0019/document.
Texto completo da fonteMost platforms that are being developed to build quantum simulators do not satisfy simultaneously all the requirements necessary to implement useful quantum tasks. Robust systems can be constructed by combining the strengths of multiple approaches while hopefully compensating for their weaknesses. This thesis reports on the progress made on two different setups that are being developed toward this goal.The first part of this thesis focuses on a hybrid system of neutral atoms coupled to superconducting qubits that is under construction at the University of Maryland. Sub-wavelength diameter optical fibers allow confining an ensemble of cold atoms in the evanescent field surrounding the fiber, which makes them ideal for placing atoms near a superconducting surface. We have developed a tapered fiber fabrication apparatus, and measured an optical transmission in excess of 99.95% for the fundamental mode. We have also optimized tapered fibers that can support higher-order optical modes with high transmission, which may be useful for various optical potential geometries.The second part of this thesis focuses on a system of neutral atoms trapped in arrays of optical tweezers that has been developed at the Institut d’Optique. Placing the atoms in highly excited Rydberg states allows us to obtain strong interatomic interactions. Using two individual atoms, we have characterized the pairwise interactions in the van der Waals and resonant dipole-dipole interaction regimes, providing a direct observation of the coherent nature of the interaction. In a three-atom system, we have finally simulated the dynamics of an elementary spin chain
Bigué, Laurent. "Reconnaissance des formes en temps réel par voie optique : étude comparative d'implantations optiques de filtres de corrélation : application au corrélateur optique à transformée de Fourier conjointe". Mulhouse, 1996. http://www.theses.fr/1996MULH0445.
Texto completo da fonteFeneyrou, Patrick. "Étude des propriétés optiques, linéaires et non linéaires, de la molécule et du cristal de 4-diéthylamino-(bêta)-nitrostyrène". Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10224.
Texto completo da fonteMessaad, Khalida. "Contribution à la conception de guides optiques à fortes susceptibilités non-linéaires d'ordre 3". Phd thesis, Université Rennes 1, 2009. http://tel.archives-ouvertes.fr/tel-00456183.
Texto completo da fonteLaddada, Réda. "Réalisation d'un microscope optique en champ proche sans ouverture : études expérimentale et théorique du contraste des images optiques". Troyes, 1999. http://www.theses.fr/1999TROY0002.
Texto completo da fonteInou, Allal. "Modélisations numériques d'oscillateurs paramétriques optiques, en régime de fortes conversions, à l'échelle nanoseconde". Limoges, 1998. http://www.theses.fr/1998LIMO0013.
Texto completo da fonteLe, fournis Romuald. "Propagation de la lumière dans la matière en présence de champs électromagnétiques". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALY011.
Texto completo da fonteIn this thesis, we focus on the analysis of forces and torques resulting from the interaction between matter and the electromagnetic field, both either described classically or quantum-mechanically. We explore how the addition of external electric and magnetic fields modifies the mechanical moments acting on the medium. External fields can have a significant impact, alter particle trajectories, induce angular momentum, or cause changes in the energy levels of quantum states.The thesis splits up into two related axes, each offering a different perspective on the interaction between light and matter in the presence of external fields.In the first axis, we delve into the field of quantum electrodynamics (QED) to study the role of the quantum vacuum in electromagnetic forces. Our focus is on two distinct classical forces: the Abraham force and the Aharonov-Casher force. Both these forces are central to the Abraham-Minkoswki controversy discussed in the first chapter of this thesis.The first axis is explored in Chapters 2 and 3, which focus on the modification of quantum vacuum momentum in the presence of matter and external electromagnetic fields. The modification of quantum vacuum momentum leads to the existence of a quantum vacuum force on matter but remains unobserved experimentally. For this investigation, we employ a QED approach along with a microscopic model.In Chapter 2, we study the contributions of the quantum vacuum to the Abraham force acting on a Rydberg atom in the presence of crossed electric and magnetic fields. Our goal is to determine whether Rydberg atoms are good candidates for the observation of the quantum vacuum contributions to the classical Abraham force.Chapter 3 is focused on the Aharonov-Casher force. This force has not been observed so far because it is extremely small. We calculate the quantum vacuum force for a Rydberg atom with a large magnetic moment exposed to an electric field to determine if the quantum vacuum is capable of generating an Aharonov-Casher force.The second axis adopts a classical approach to the interaction between light and matter, focusing on the torques exerted on matter by the electromagnetic field.Chapter 4 is devoted to the study of the angular momentum radiation from a source surrounded by a magneto-birefringent environment. More precisely, we characterize the influence of multiple light scattering on angular momentum radiation as well as on the torque acting on matter.Although both axes adopt different approaches, they remain closely interconnected. Force and torque, fundamental in mechanics, share an intimate relationship, and the study of both provides a more comprehensive picture of the interactions between light and matter in the presence of external fields. As a result, both axes complement each other, offering a global and enlightened perspective on this field of study from complementary angles. A detailed presentation of both lines of research including their mathematical tools is provided in Chapter 1
Schwartz, Noah. "Précompensation des effets de la turbulence par optique adaptative : application aux liaisons optiques en espace libre". Phd thesis, Université de Nice Sophia-Antipolis, 2009. http://tel.archives-ouvertes.fr/tel-00771276.
Texto completo da fonteLorchat, Étienne. "Optical spectroscopy of heterostructures based on atomically-thin semiconductors". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAE035.
Texto completo da fonteDuring this thesis, we have fabricated and studied by optical spectroscopy, van der Waals heterostructures composed of semiconductor monolayers (transition metal dichalcogenides, TMD) coupled to a graphene monolayer or to a plasmonic resonator. We have observed significant changes in the dynamics of the TMD optically excited states (excitons) when it is in direct contact with graphene. Graphene neutralizes the TMD monolayer and enables non-radiative transfer of excitons within less than a few picoseconds. This energy transfer process may be accompanied by a considerably less efficient, extrinsic photodoping. The reduced lifetime of TMD excitons in the presence of graphene has been exploited to show that their valley pseudo-spin maintains a high degree of polarization and coherence up to room temperature. Finally, by strongly coupling TMD excitons to the modes of a geometric phase plasmonic resonator, we have demonstrated, at room temperature, that the momentum of the resulting chiral polaritons (chiralitons) is locked to their valley pseudo-spin
Tackmann, Gunnar. "Interférométrie Raman avec des atomes en chute libre et piégés". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00966091.
Texto completo da fonteLe gyromètre CASI est basé sur un double interféromètre Raman aux trajectoires atomiques contrapropageantes. Cet ouvrage présente des études sur la stabilité du capteur et une amélioration de la sensibilité aux rotations d'un ordre de grandeur par rapport a l'état précédent. Une sensibilité de 2×10-8 rad/s après 4000 s de moyennage a été démontrée en exploitant, pour le corriger, la corrélation du signal de rotation avec le temps d'arrivée des échantillons atomiques.
L'expérience FORCA-G vise à réaliser des mesures de forces a faible distance à l'aide d'interféromètres Raman basés sur un effet tunnel induit par laser dans un réseau optique. Des mesures avec une sensibilité aux accélérations de 2×10-5 g/√Hz sont présentées. La sensibilité obtenue après une intégration de 150 s permettra de réaliser des mesures de la force de Casimir-Polder avec une incertitude statistique de 1 % à une distance atome-surface de l'ordre de 5 µm. Par ailleurs, l'implémentation d'un transport cohérent des atomes dans des réseaux optiques accélérés a été effectuée, qui sera utile pour les mesures futures.
Decombe, Jean-Baptiste. "Développement et application d’une pince optique à fibres nano-structurées". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY035/document.
Texto completo da fonteOptical tweezers allow to trap and manipulate objects without any mechanical contact with light and with an extreme accuracy. This non-invasive and non-destructive technique is of large interest in many scientific domains such as biophysics and medicine. Conventional optical tweezers use a laser beam which is strongly focalised by a microscope objective.The use of optical fibers attracts increasing attention as highly flexible and compact tools for particle trapping. Fiber-based optical tweezers do not require bulky optics and require only little alignments.In this context, the objective of this thesis was to develop a dual fiber nano-tip optical tweezers in order to trap particles with micro and nano-meter sizes. Our tweezers consist of two chemically etched optical fiber tips placed in front of each other with typical gaps from 20~nm to 20~µm. This dual contra-propagative beams configuration allow to cancel light radiation pressure. Efficient trapping can thus be obtained at relative low light intensities. Moreover, strong focusing is not required. Our device present an high flexibility due to in situ optimization and control of the fibre positions and individual particle manipulation without any substrate.During our work, we experimentally demonstrated stable and reproducible trapping of one or several particles in suspension. Various dielectric particles were trapped, from one micrometer polystyrene beads to luminescent YAG:Ce particles with diameters down to 60~nm. During this thesis, the latter were specifically elaborated and optimized for the optical trapping. We also measured optical forces applied to trapped particles by analysing their residual Brownian motion. We showed the trapping potential is of harmonic shape, allowing to define its optical stiffness.vspace{10pt}Finally, by modifying the emitted optical beam shape, we were able to improve specific tweezers characteristics. On one hand, nondiffracting quasi-Bessel beams allow us to get a stable trapping at large fiber-to-fiber distances.On the other hand, the use of metallised fiber tips allows to improve the beam confinement and enhance optical forces while reducing light intensity. We proved the near-field coupling between two metallised tips which were especially elaborated in this work. Those last results open promising perspectives for the development of plasmonic tweezers working in the near-field, which are especially well adapted for nano-particles trapping
Wioland, Hervé. "Etude en champ proche d'effets optiques et magnéto-optiques par microscopie locale à sonde diffusante". Troyes, 2000. http://www.theses.fr/2000TROY0002.
Texto completo da fonteLebourgeois, Frank. "Approche mixte pour la reconnaissance des documents imprimes". Lyon, INSA, 1991. http://www.theses.fr/1991ISAL0013.
Texto completo da fonteA recognition system for multi font printed documents using contextual informations about typography, structure of document and syntax, has been developed. First, a quick bottom up method to separate text from image and recognize logical structure of documents has been achieved. A mixed approach has been used to recognize individual characters. A first stage realizes a compaction at the character level compared to a dynamically built librairy of shapes. The high redundancy of character's image in printed document justifies this approach. A second stage structurally recognizes the previously built models of characters. A mixed syntaxic and statistic stage is used simultanous. It o perform a high recognition rate
Togni, Olivier. "Force des graphes : indice optique des réseaux". Bordeaux 1, 1998. http://www.theses.fr/1998BOR10596.
Texto completo da fonteDeumié-Raviol, Carole. "Ellipsométrie sur champ diffus et analyse multi-échelle de la microstructure des multicouches optiques : diffusion lumineuse, microscopie à force atomique, microscopie à effet tunnel optique". Aix-Marseille 3, 1997. http://www.theses.fr/1997AIX30087.
Texto completo da fonteLabarrière, Luc. "Spectroscopic properties of environmental relevant systems : 2’,3-dihydroxyflavone-ion complexes and polycyclic aromatic hydrocarbons : a joint experimental and theoretical study". Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR069.
Texto completo da fonteThis manuscript reports the results of an experimental and theoretical study of two molecular systems of environmental interest: 2',3-dihydroxyflavone (2'3HF) and polycyclic aromatic hydrocarbons (PAH). These systems were studied by a combination of electronic spectroscopic techniques (absorption and fluorescence) and quantum chemical calculations (DFT and TD-DFT). In the first part of this thesis, it is shown that 2'3HF has singular acid-base properties compared to other flavonols. The decrease of the pKa by several units is attributed to the presence of a hydrogen-bond network. In the excited state, an intramolecular proton transfer causes a dual fluorescence. An additional emission band, seemingly originating from a tautomeric form perturbed by interaction with the solvent, was revealed. Finally, an exhaustive study of the Ca(II), Mn(II) and Zn(II) complexes showed the formation of chelates with the α-hydroxyketone function. In the second part, three structural hypotheses to explain the experimental observation of visible-range laser-induced fluorescence (LIF) were explored. A study of van der Waals (vdW) dimers of PAHs provided insights into the nature of the monomer interaction and highlighted the difficulty of modelling these systems. However, the calculated electronic transitions suggest that these species cannot be responsible for the LIF signals. Secondly, an identical study of aliphatically bridged PAHs showed very similar results to vdW dimers, ruling out their involvement in the observed fluorescence. Finally, the hypothesis of emission from PAH radicals was explored. The latter is very promising and opens the way for further experimental and theoretical studies
Brière, Benjamin. "Propriétés optiques de matériaux à fortes corrélations électroniques en conditions extrêmes". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4020/document.
Texto completo da fonteMaterials with strongly correlated electrons belong to the most intriguing systems in condensed matter physics due to their great variety of properties discovered during the last decades such as high temperature superconductivity, molecular conductors and colossal magnetoresistance. During this thesis, two types of strongly correlated materials have been studied: the quadruple perovskite EuCu3fe4Oi2 and the molecular conductors [Au(Et-thiazdt)2J. EuCu3Fe4Oi2 undergoes a metal to insulator transition at low temperature (240K), and [Au(Et-thiazdt)2J goes from a Mott insulator to a correlated metal state under high pressure. Infrared microspectroscopy measurements allowed us to probe the low energy electrodynamic of these systems. Ab-initio calculations were also used to understand the mechanisms of the transitions and the role of electronic correlations in the material
Berguiga, Lotfi. "Etude et réalisation d'un microscope de champ proche optique avec asservissement de type "shear force" : application à l'étude en champ proche du vieillissement de fibres optiques". Dijon, 2001. http://www.theses.fr/2001DIJOS023.
Texto completo da fonteChallita, Zalpha. "Optique astronomique et plasticité : développements en fabrication optique pour des miroirs actifs de formes libres". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4775/document.
Texto completo da fonteThe next instrumental decade in astronomy aims to be extreme. It opens with the arrival of ELTs (Extremely Large Telescopes). Their giant primary mirrors will increase the light collecting power and the angular resolution, key parameters for observing and imaging of celestial bodies. However, this also leads to an increase in the complexity, size and weight of their focal-plane instruments, to minimize flux lost and to correct for the aberrations introduced. A solution would be to implement freeform mirrors inside the optical systems of these instruments. Today, it is not possible to obtain these exotic mirror shapes using the current optical fabrication techniques and new technological breakthroughs in this domain are essential. This PhD thesis present research and development work, in upstream phase, of an innovative manufacturing process to supply freeform mirrors, which should meet required optical performances in Visible and Infrared wavelength astronomical observations. This method is an evolution of Active Optics techniques and based on the ability of metallic materials to plasticize. However, the plasticity of metallic materials remains a field of non-linear behaviours and analytically complex. It is important to compare modeling from finite element analysis and real tests. For these tests, the complete manufacturing steps of the metallic substrates were put in place. The first mirrors obtained will highlight the main working parameters and their sensibility levels, and then converge toward reliable finite elements models and a mastered solution of optical freeform mirrors fabrication
Ambs, Pierre. "Traitement de l'information par processeurs optiques : application à la reconnaissance de formes". Mulhouse, 1987. http://www.theses.fr/1987MULH0049.
Texto completo da fonteAmbs, Pierre. "Traitement de l'information par processeurs optiques application à la reconnaissance de formes /". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37602342m.
Texto completo da fonteLecarme, Olivier. "Propriétés optiques de colloïdes assemblés : plasmonique et confinement diélectrique". Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00680026.
Texto completo da fonteYao, Jianping. "Algorithmes pour la reconnaissance de formes optique invariante aux distorsions". Toulon, 1997. http://www.theses.fr/1997TOUL0014.
Texto completo da fonteDelatour, Thierry. "Mise en évidence par spectrométries optiques de formes tautomères caractéristiques d'un pyridylazo diethylaminophénol". Nancy 1, 1987. http://www.theses.fr/1987NAN10159.
Texto completo da fonteDelatour, Thierry. "Mise en évidence par spectrométries optiques de formes tautomères caractéristiques d'un pyridylazo diethylaminophénol". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37604350q.
Texto completo da fonteHilico, Adèle. "Capture de forces à atomes piégés dans un réseau optique : caractérisation des performances". Thesis, Paris, Ecole normale supérieure, 2014. http://www.theses.fr/2014ENSU0007/document.
Texto completo da fonteThe thesis presents the set up of the second version of the experiment FORCA-G (CAsimir FORce and Gravitation at short range). The purpose of this experiment is the measurement of short-range interactions between an atom and a massive surface. The measurement is realised thanks to atom interferometers using atoms trapped in a 1D vertical optical lattice. The energy levels of atoms in such a trap are shifted from lattice site to another by the force we aim at measuring. We move the atoms from site to site using counter-propagating Raman transitions. The atoms are moved from Δm lattice sites only if the Raman frequency matches υHFS +∆m.υB where υHFS is the frequency of the hyperfine ground state transition and υB is the Bloch frequency and represents the difference of potential energy between two wells in the case where the atoms are far from the surface. This thesis presents the implementation of a setup properly dedicated to FORCA-G in which the measurement of short-range forces will be possible. It reaches an improved short-term relative sensitivity on the measurement of the Bloch frequency of at 3.9 10-6 at 1s. It contains the studies of the limits in the sensitivity, the accuracy and the contrast losses. It also presents the implementation of a dipolar trap to further cool the atoms and increase their density (crossed dipolar trap with a 1064 broadband laser)
Neradovskiy, Maxim. "Guides d’ondes dans un cristal de niobate de lithium périodiquement polarisé : fabrication et étude par des techniques de microscopie à sonde locale". Thesis, Nice, 2016. http://www.theses.fr/2016NICE4035/document.
Texto completo da fonteThe investigation of influence of the soft proton exchange (SPE) optical waveguide (WG) creation onperiodically poled lithium niobate (PPLN) has been done. It has been shown that the WG fabricationprocess can induce the formation of needle like nanodomains, which can be responsible for thedegradation of the nonlinear response of the WG created in PPLN crystals. The domain structure (DS)evolution has been studied in congruent lithium niobate (LN) crystals with surface layers modified bythree different proton exchange techniques. The significant decrease of the nucleation threshold fieldand qualitative change of domain rays nucleation and growth have been revealed. The formation of abroad domain boundary and dendrite domain structure as a result of nanodomains merging in front ofthe moving rays has been demonstrated. The formation of DS in LN with SPE by irradiation of coveredby electron resist polar surface of LN has been investigated. Formation of domains with arbitrary shapesas a result of discrete switching has been revealed. Finally, it has been demonstrated that electron beamirradiation of lithium niobate crystals with surface resist layer can produce high quality periodical domainpatterns after channel waveguide fabrication. Nonlinear characterizations show that the conversionefficiencies and the phase matching spectra conform to theoretical predictions, indicating that thiscombination presents a great interest for device fabrication. Second harmonic generation withnormalized nonlinear conversion efficiency up to 48%/(W cm2) has been achieved in such waveguides
Aubert, Sébastien. "Etude de guides d'ondes intégrés sur verre par microscopie optique en champ proche utilisant des sondes diffusantes sans ouverture". Troyes, 2003. http://www.theses.fr/2003TROY0008.
Texto completo da fonteThe light propagation in waveguides cannot be directly observed using far field optics. Optical near-field microscopy allows this observation using tapered optical fiber probes. These probes are called aperture probes. In this thesis, we present for the first time the use of metallic of silicon atomic force microscope probes for the same application. These probes are called apertureless probes. An apertureless scanning near-field optical microscope has been developed from a commercial atomic force microscope and used in order to study ion exchange optical integrated devices. After we show how this set-up can detect an evanescent field using the tapping mode and a lock-in, the image formation process is analyzed in detail. It points out an interference effect between the field scattered by the probe and the field scattered by defects closed to the probe. This microscope then leads to the mapping of propagating field, the measurement of mode profiles at the component output and the determination of progatating constants. We show the experimental set-up, results for a straight waveguide, the imaging of a Y junction imbalance and we present a heterodyne interferometric detection to improve performances
Al, Falou Ayman. "Implantation optique de correlateurs multivoies appliques a la reconnaissance des formes". Rennes 1, 1999. http://www.theses.fr/1999REN10099.
Texto completo da fonteCapitaine, Thierry. "Reconnaissance optique de partitions musicales". Compiègne, 1995. http://www.theses.fr/1995COMPD852.
Texto completo da fonteMonsterleet, Aymeric. "Etude des architectures optiques pour la génération de formes d'ondes électriques arbitraires pour applications radar". Paris 11, 2005. http://www.theses.fr/2005PA112283.
Texto completo da fonteEmonin, Stéphanie. "Analyse de circuits optiques passifs et actifs en microscopie a sonde locale". Dijon, 1998. http://www.theses.fr/1998DIJOS038.
Texto completo da fonteTomczak, Jan Martin. "Propriétés spectrales et optiques des Matériaux corrélés". Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00003163.
Texto completo da fonteGagné, Christian. "Algorithmes évolutionnaires appliqués à la reconnaissance des formes et à la conception optique". Thesis, Université Laval, 2005. http://www.theses.ulaval.ca/2005/22701/22701.pdf.
Texto completo da fonteEvolutionary Algorithms (EA) encompass a family of robust search algorithms loosely inspired by natural evolution. These algorithms are particularly useful to solve problems for which classical algorithms of optimization, learning, or automatic design cannot produce good results. In this thesis, we propose a common methodological approach for the development of EA-based intelligent systems. This methodological approach is based on five principles : 1) to use algorithms and representations that are problem specific ; 2) to develop hybrids between EA and heuristics from the application field ; 3) to take advantage of multi-objective evolutionary optimization ; 4) to do co-evolution for the simultaneous resolution of several sub-problems of a common application and for promoting robustness ; and 5) to use generic software tools for rapid development of unconventional EA. This methodological approach is illustrated on four applications of EA to hard problems. Moreover, the fifth principle is explained in the study on genericity of EA software tools. The application of EA to complex problems requires the use of generic software tool, for which we propose six genericity criteria. Many EA software tools are available in the community, but only a few are really generic. Indeed, an evaluation of some popular tools tells us that only three respect all these criteria, of which the framework Open BEAGLE, developed during the Ph.D. Open BEAGLE is organized into three main software layers. The basic layer is made of the object oriented foundations, over which there is the generic framework layer, consisting of the general mechanisms of the tool, and then the final layer, containing several specialized frameworks implementing different EA flavors. The tool also includes two extensions, respectively to distribute the computations over many computers and to visualize results. Three applications illustrate different approaches for using EA in the context of pattern recognition. First, nearest neighbor classifiers are optimized, with the prototype selection using a genetic algorithm simultaneously to the Genetic Programming (GP) of neighborhood metrics. We add to this cooperative two species co-evolution a third coevolving competitive species for selecting test data in order to improve the generalization capability of solutions. A second application consists in designing representations with GP for handwritten character recognition. This evolutionary engineering is conducted with an automatic positioning of regions in a window of attention, combined with the selection of fuzzy sets for feature extraction. This application is used to automate character representation search, which is usually conducted by human experts with a trial and error process. For the third application in pattern recognition, we propose an extensible system for the hierarchical combination of classifiers into a fuzzy decision tree. In this system, the tree topology is evolved with GP while the numerical parameters of classification units are determined by specialized learning techniques. The system is tested with three simple types of classification units. All of these applications in pattern recognition have been implemented using a two-objective fitness measure in order to minimize classification errors and solutions complexity. The last application demonstrate the efficiency of EA for lens system design. Selfadaptative evolution strategies, hybridized with a specialized local optimisation technique, are used to solve two complex optical design problems. In both cases, the experiments demonstrate that hybridized EA are able to produce results that are comparable or better than those obtained by human experts. These results are encouraging from the standpoint of a fully automated optical design process. An additional experiment is also conducted with a two-objectives fitness measure that tries to maximize image quality while minimizing lens system cost.
Zuquete, Guarato Alexandre. "Métrologie 3D de pièces de formes complexes par moyens optiques : Une application à l'équilibrage de vilebrequins". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00942486.
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