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Yes / The Molecular Stress Function (MSF) constitutive model with convective constraint release mechanism has been shown to accurately fit a large range of viscometric data, and also shown to give strong vortex growth in flows of LDPE through planar and axisymmetric contractions. This work compares simulation and experimental results for 3-D flows of Lupolen 1840H LDPE through a contraction slit; 3-D effects are introduced by using a slit with a low upstream aspect ratio of 5:3. Comparisons are made with vortex opening angles obtained from streak photography, and also with stress birefringence measurements. The comparisons are made with two versions of the convective constraint release (CCR) mechanism. The simulated vortex angles for one version of the CCR mechanism are found to approach what is seen experimentally. The best-fit value for the stress optical coefficient was found to vary between CCRs and to decrease with flow rate. This is partially explained by different centreline elongational rates with the two CCRs, which in turn is related to different opening angles. A 3-D simulation is compared to the corresponding 2-D simulation. It is shown that both velocity vectors and birefringence show only small changes to around 60% of the distance to the side wall.

The unique features of flexoelectric and dielectric effects are investigated, and exploited for a variety of functions, in a wide range of helicoidal liquid crystal systems, including non-chiral, cholesteric and blue phases. Electrooptic techniques are developed to measure flexoelectric parameters in non-chiral and cholesteric liquid crystals using twisted nematic and Grandjean geometries respectively. A crystal rotation method, and using a lock-in amplifier, is used to enable the measurement of a very small e/K of 0.011 C/N^-1m^-1. Enhancement in chiral-flexoelectric switching is demonstrated theoretically in liquid crystals with negative dielectric anisotropy and in systems in which the pitch is constrained to be other than the natural pitch. A methodological framework for inducing stable Uniform Lying Helix alignment is developed based on weak homeotropic alignment conditions and a method to bias the helicoidal axis orientation; a series of approaches within this framework are demonstrated, including nano-grooved interfaces, periodic boundaries conditions, in-plane fields, and mould-templated micro-channels. The latter approach is potentially commercially viable for sub-millisecond electrooptic technology. The contribution to a cholesteric material's effective dielectric permittivity of flexoelectric polarization is formulated, and an ability to switch a cholesteric between Grandjean and lying-helix configurations based on the dispersion in the flexoelectric polarization and resultant relaxation in dielectric properties is demonstrated. The flexoelectric contribution to dielectric permittivity is exploited to enable switching in bistable reflective displays and alignment of the Uniform Lying Helix. The existence of a flexoelectric contribution to Kerr switching in blue phases is demonstrated, and a semi-empirical model for the effect is developed. The effect is the first known example of a non-polar flexoelectrooptic effect. Independent flexoelectric and dielectric contributions to Kerr switching in blue phases are measured experimentally by measuring the induced birefringence as a function of driving frequency in flexoelectric- and dielectric-dominated wide-temperature-range blue phase materials.

Ces travaux de thèse, consacrés à l'étude et analyse quantitative d'images de phase obtenues par interférométrie à décalage quadri-latéral, ont pour but la caractérisation d'un point de vue métrologique d'un outil de mesure et de ses différentes applications. Cette technique d'interférométrie, développée initialement par la société Phasics pour les marchés de la métrologie optique et de la caractérisation de faisceaux laser essentiellement, peut aussi permettre d'obtenir la cartographie d'un champ électromagnétique complexe grâce à une mesure de front d'onde. En l'utilisant sur un microscope en condition d'imagerie, ont été obtenues des images de l'intensité et de la différence de chemin optique introduite par un échantillon semi-transparent, définissant ainsi une nouvelle technique de contraste de phase quantitatif. La première partie de cette thèse sera consacrée aux techniques en microscopie qui permettent une quantification. Nous verrons les enjeux de l'obtention de ce caractère quantitatif et ce qu'il signifie dans le cadre de différentes techniques utilisant la fluorescence. On étudiera la mesure dans le cadre d'une approximation dite "projective" réalisant certaines hypothèses. On verra quelles sont les grandeurs accessibles grâce à une mesure dans le cadre de cette approximation et quelles applications en biologie peuvent être développées concernant les éléments isotropes dans une première partie et les éléments anisotropes dans une seconde partie.Nous démontrerons la possible transposition de ces applications réalisées en deux dimensions en trois dimensions avec une résolution axiale suffisante permettant une reconstruction tomographique. / The aim of this thesis, dedicated to the study and quantitative analysis of phase images obtained thanks to quadri-wave lateral shearing interferometry, is to caracterize a metrological tool and its three proposed different applications.This work has been done in collaboration between Institut Fresnel (Marseille, France) and Phasics company (Palaiseau, France) and continues that of Pierre Bon who has been in charge the application this technique to microscopy. This interferometric technique, developped by Phasics, for optical metrology and lasers characterization, allows to record complex eletromagnetic field maps thanks to a wave front measurement. By using it in the microscope image plane, one can obtain inetnsity and optical path difference images of a semi-transparent biological sample. this technique is now considered as a new quantitative phase contrast technique.The first part of this manuscript will be a state of the art of quantitative microscopy techniques. The issues of quantification and its meanings in the framework of different fluorescent and phase based techniques will be discussed.A description of the technique that is used and its comparison with similar phase techniques will be done.The measurement, under the projective approximation, is studied leading to different variables. We show different applications concerning isotropic elements in a first part and anisotropic elements in the second one.We show how this measurement is trnasposed to the third dimensions allowing three dimensional imaging and complete reconstruction of refractive index maps of biological samples.

Cette thèse concerne la production et le contrôle d'hologrammes de haute qualité par un modulateur de phase à cristaux liquides (SLM) et l'utilisation de ces hologrammes pour la manipulation d'atomes froids. Ces hologrammes utilisés pour mettre en forme des faisceaux lasers et créer des potentiels dipolaires doivent être de bonne qualité. Or le SLM a des défauts qui peuvent les dégrader. Pour mesurer ces défauts nous avons développé une méthode reposant sur la mesure par polarimétrie de la biréfringence du SLM. La cartographie de biréfringence permet de mesurer l'hologramme en temps réel sans perturber l'expérience en cours. C'est donc une mesure in-situ. Une fois mesurés les défauts sont corrigés par une rétroaction sur la consigne donnée au SLM. Pour le démontrer nous avons créé un défaut artificiel avec un pointeur laser et nous l'avons réduit à λ/7 soit une amélioration de 42 %. Ensuite avec l'objectif d'appliquer des potentiels produit par un SLM aux atomes froids, j'ai dessiné, conçu puis réalisé en partie une expérience basée sur un jet d'atomes froids de rubidium issu d'un MOT-2D. Dans le chapitre correspondant je présente une étude de la faisabilité d'une expérience de guidage du jet d'atomes froids par un mode de Laguerre Gauss désaccordé vers le bleu de la transition. Nous avons montré que dans un tel guide le chauffage par émission spontanée est plus faible que dans un guide gaussien usuel désaccordé vers le rouge de la transition. De plus en réduisant la divergence naturelle du jet issu du MOT-2D nous devrions augmenter le flux d'atomes et améliorer l'efficacité de chargement d'un MOT-3D par un MOT-2D. / This thesis reports on the production and monitoring of high quality holograms generated by a liquid crystal spatial light modulator (SLM), and the application of these holograms to cold atoms manipulation. In order to produce accurate optical potentials by shaping a laser beam we need high quality holograms. Nevertheless SLMs suffer from defects which limit the quality. To measure defects we have developed a method based on polarimetry to get the birefringence map of the SLM. Birefringence mapping is suitable to monitor the hologram without disturbing the on-going experiment. It's an in-situ measurement. After the measurement, defects are corrected by a feedback on the input hologram. As a proof we created an artificial defect with a laser pointer and reduced it to λ/7 which corresponds to a 42% improvement. Our second goal is to apply SLM-shaped potentials to cold atoms, so I designed and did part of an experiment based on a cold atom beam provided by a rubidium 2D-MOT. In the corresponding chapter I've studied the feasibility of guiding the cold atom beam with a blue-detuned Laguerre-Gaussian beam. We showed that in such a guide the spontaneous emission is lower than in the usual red detuned gaussian guide case. Furthermore by reducing the cold atom beam divergence we expect to enhance the atomic flux and improve the loading efficiency of a 3D-MOT from a 2D-MOT.

O colágeno é a forma funcional de um oligômero biológico, cujos monômeros são aminoácidos quirais. Tecidos ricos em colágeno são estruturas opticamente anisotrópicas, birrefringentes e não-lineares. O objetivo deste trabalho foi caracterizar o colágeno tipo I não irradiado e após irradiação com laser de He-Ne polarizado, utilizando a microscopia de polarização para investigação da birrefringência, e a geração de segundo harmônico (GSH) para análise da susceptibilidade não-linear. Doze ratos Wistar foram divididos em quatro grupos, de acordo com as idades: 34, 48, 62 e 76 dias. Os grupos receberam, respectivamente, 1; 5; 9 e 13 irradiações de D= 1J/cm2, durante 46s, no tendão de Aquiles que, aleatoriamente, foi escolhido ser o direito ou esquerdo. Os animais foram então sacrificados e os tendões extraídos para a preparação das amostras. Para a microscopia de polarização foram obtidos cortes com 8μm de espessura, e as birrefringências de forma e intrínseca foram avaliadas. Para a GSH foi utilizado um laser de Ti:Safira (150fs) com 76MHz de taxa de repetição, diâmetro do feixe φ= 40μm, comprimento de onda central λ= 800nm e Δλ= 10nm e Pp= 110mW. Um polarizador linear foi posicionado no caminho do feixe. Duas objetivas foram utilizadas para focalizar e coletar a radiação incidente e emergente da amostra, respectivamente. Um analisador, também linear, foi introduzido logo após a objetiva coletora. Um filtro absorvedor na faixa infravermelha do espectro eletromagnético, mas transmissor na faixa azul, foi utilizado para garantir que apenas λ= 400nm era medido. A razão, ρ, entre dois tensores de hiperpolarizabilidade independentes foi estudada. As amostras irradiadas apresentaram maior birrefringência (Δn) e maior susceptibilidade não-linear (ρ), em comparação com as não irradiadas. Estes resultados indicam que o laser de He-Ne polarizado alinha as fibrilas de colágeno ao longo eixo do tendão. / The collagen is the functional form of a biological oligomer whose monomers are chiral amino acids. Tissues filled up of collagen are anisotropic optically structures, birefringent and nonlinear. The purpose of this study was characterizing nonirradiated and polarized He-Ne laser irradiated type I collagen using polarized light microscopy to investigate the birefringence and the second harmonic generation (SHG) to analyze the nonlinear susceptibility. Twelve Wistar rats were alienated into four groups according to the ages: 34, 48, 62 and 76 days. The groups received, respectively, 1; 5; 9; and 13 irradiations of D= 1J/cm2 during 46s on Achilles tendon, which was chosen randomly as right or left. Thereafter, the animals were sacrificed and the tendons were extracted to prepare the specimens. For polarized light microscopy, eight-μm sections were obtained to evaluate the form and intrinsic birefringences. For SHG, it was used a Ti:Safira (150fs) laser at a repetition rate of 76MHz, beam diameter of φ= 40μm, wavelength of λ= 800nm and Δλ= 10nm and Pp= 110mW. The beam passed through a linear polarizer and two microscope objectives were used to focalize and collect the incident and emergent radiation, respectively. A second linear polarizer was placed after of collecting objective. An infrared absorber and blue transmitter filter was used a sure that only λ= 400nm was measured. The ratio, ρ, between two hyperpolarizability tensors was studied. The irradiated samples presented higher birefringence (Δn) and nonlinear susceptibility (ρ) when compared to nonirradiated samples. These results indicate that a polarized He-Ne laser aligns the collagen fibrils to the long tendon axis.

Este trabalho tem como objetivos projetar, construir e caracterizar experimentalmente metamateriais quirais bi-planares para faixa de micro-ondas com o objetivo de investigar a rotação de campo como transdutor em aplicações de biossensoriamento. As estruturas metamateriais estudadas foram primeiramente modeladas e caracterizadas com o uso de aplicativos computacionais comerciais baseadas no método dos elementos finitos, onde os parâmetros geométricos das estruturas foram definidos para operarem na faixa de 8GHz a 12GHz. A partir dos projetos das estruturas simuladas, os metamateriais foram construídos e caracterizados experimentalmente. No estágio de fabricação, foi desenvolvida uma técnica inédita de confecção de metamateriais em placas de circuito impresso flexível. Esta técnica, baseada no processo tradicional de fabricação de placas de circuito impresso, utiliza uma combinação de filmes finos de alumínio e folhas plásticas adesivas flexíveis formando, assim, uma folha metalizada fina e flexível. Além de ser tão eficiente quanto o método convencional, a abordagem proposta utiliza materiais de baixo custo, podendo ser adaptada a outros substratos de qualquer material, formato e espessura. Também foram projetadas e construídas placas de metamateriais com geometrias similares via método tradicional (FR4 e cobre) com o objetivo de validar os procedimentos propostos neste trabalho. A caracterização experimental dos metamateriais quirais foi realizada, por meio de antenas cornetas e analisador de redes. As propriedades efetivas do meio (quiralidade, ângulo de azimute, elipticidade, e índice de refração) foram obtidas a partir dos parâmetros-S do material, por meio de um método de extração de parâmetros. Como esperado, os resultados experimentais tiveram boa concordância com os obtidos numericamente. Por fim, foi proposta uma aplicação de metamaterial quiral utilizando suas características de rotação de campo como transdutor para a medida de glicose em amostras aquosas. No experimento proposto, o ângulo de azimute de uma onda plana polarizada que atravessa o material foi obtido numericamente e sua rotação de campo foi diretamente correlacionada com a concentração de glicose. Os resultados indicaram uma elevada sensibilidade mesmo para baixas concentrações de glicose, demonstrando que a rotação de campo pode realmente ser utilizada para este propósito. / This work focus on the design, fabrication and experimental characterization of bi-planar chiral metamaterials in the microwave frequency range aiming at investigating field rotation as a possible transductor for biosensig applications. First, the metamaterial structures were simulated with commercial-based finite element methods, where the structures geometric parameters were defined to operate in the range of 8-12 GHz. Next, the metamaterials were fabricated and characterized experimentally. We have also developed a new technique for making metamaterials on flexible printed circuit boards. This proposed technique, based on traditional processes of printed circuit boards fabrication, utilizes combination of thin aluminum films and adhesive flexible plastic foils, thus forming a thin, flexible metallic foil. In addition to being as efficient as the conventional method, the proposed approach utilizes low cost materials with low insertion loss that can be adapted to substrates of any material, shape and thickness. We have also designed and fabricated metamaterials with similar geometries via the traditional circuit board method (FR4 and copper) in order to validate the procedures proposed in this work. The experimental characterization of the chiral metamaterials was carried out with antenna horns and a network analyzer. The effective medium parameters (chirality, azimuth angle, ellipticity, and refractive index) were then obtained from the Sparameters of the material via a parameter extraction method. The experimental results were in good agreement with those obtained numerically. Finally, we proposed a new chiral metamaterial application using its field rotation characteristics as a transductor for measuring glucose concentration in aqueous solutions. In the proposed experiment, the azimuth angle of a polarized plane wave propagating through the material was numerically calculeted and its polarization field rotation was directly correlated with the glucose concentration. The results indicated a very high sensitivity even for very low glucose concentrations, indicating that field rotation can indeed be used for this purpose.

Polímeros contendo grupos azo-benzênicos têm sido estudados devido a sua capacidade para óptica não linear, formação de superfícies de relevo e de birrefringência fotoinduzida. O fator que possibilita essas aplicações é a propriedade de fotoisomerização reversível trans-cis-trans do grupo azo que produz a sua reorientação molecular. Neste trabalho foram produzidos filmes casting do poliuretano MDI-DR19 derivado de azo-benzeno. Estudou-se o crescimento e decaimento da birrefringência para diferentes valores de potência da luz de excitação da fotoisomerização. Os resultados experimentais do crescimento e decaimento foram analisados usando duas exponenciais e eles mostraram que o polímero MDI-DR19 apresenta boas características para utilização em armazenamento óptico pois cerca de 65% da birrefringência induzida no material permanece por longos intervalos de tempo. Ilustramos o processo de armazenamento de informação gravando uma imagem de birrefringência num filme de MDI-DR19. Foram também produzidas grades de relevo em filmes de MDI-DR19 utilizando franjas de interferência produzidas com luz de polarização P e S. Essas grades apresentaram alta uniformidade e características compatíveis com as mostradas na literatura. / Polymers containing azobenzenic groups have been studied due to their applications on non-linear optics, surface relief gratings (SRG) and photoinduced anisotropy for optical storage. The reversal photoisomerization trans-cis-trans property of the azo group induces a molecular reorientation. In this work, cast films of na azobenzene derivative, the polyurethane MDI-DR19, were studied. The build-up and decay of the birefringence were studied as a function of the photoisomerization exciting light power. The data of the build-up and decay of the birefringence were fitted with a bi-exponential function, which shows the stability of the MDI-DR19 for application in optical storage, since 65% of the induced birefringence remains after a long time. The optical storage is illustrated by recording a birefringence image in a film of MDI-DR19. It was also performed a SRG over films of MDI-DR19 applying an interference finger pattern with a P and S polarized light. The light induced gratings shows good uniformity and characteristics compatible with those presented in the literature.

A proposta deste estudo foi comparar a eficácia de tratamento da aplicação tópica de hidrocortisona, do ultra-som terapêutico e da fonoforese no processo de reparo do tendão de Aquiles (tendo calcaneus) de ratos, após tenotomia. O grupo controle foi definido como tenotomizados com simulação da aplicação sônica e tendões não tenotomizados. Os dois grupos tratados com ultra-som terapêutico foram no modo pulsado. A irradiação do ultra-som terapêutico foi realizada na freqüência de 1 MHz e uma intensidade de 0.5 Watts por centímetro ao quadrado (SATA), por cinco minutos cada sessão. No 13° dia de pós-operatório, os tendões foram removidos e analisados por meio da microscopia de luz polarizada, com o propósito de investigar e medir a organização das fibras de colágeno, por meio da birrefringência. Os resultados demonstraram que o grupo tratado com a aplicação tópica de hidrocortisona apresentou valores estatísticos similares ao grupo que recebeu simulação sônica, indicando que não houve penetração da hidrocortisona e que as moléculas de colágeno responderam a estimulação ultra-sônica. Tal fato acontece provavelmente originado pelo efeito piezoelétrico que o ultra-som causa no tecido. O tratamento com fonoforese demonstrou ser o método mais eficiente, devido a maior birrefringência, revelando melhor organização e agregação das fibras de colágeno. Esses achados permitem concluir que o ultra-som terapêutico estimula a aceleração do processo de reparo tecidual e induz a penetração transcutânea da hidrocortisona a 10% numa concentração terapêutica / The purpose of this study was to compare the treatment efficacy of topic hydrocortisone appliance, therapeutic ultrasound and phonophoresis on the rats’ Achilles tendon (tendo calcaneus) repair process after tenotomy. The control group was designed in tenotomized with sham sonic application and non-tenotomized tendons. The two treated groups with therapeutic ultrasound was made in a pulsed mode. The irradiation of therapeutic ultrasound was performed at a frequency of 1 MHz and an intensity of 0.5 Watts for square centimeter (SATA), for five minutes each session. On the 13 th postoperative day, the tendons were removed and analyzed using the polarized light microscopy, with the purpose to detect and measure the organization of collagen fibers through birefringence. The results showed that the treated group with the hydrocortisone topic appliance showed similar statistician values of group that received sham sonic treatment, indicating that not have delivery transdermal and that the molecule of collagen respond to the ultrasonic stimulation. This fact occurs probably by piezoelectric effect originated by ultrasound on the tissue. The treatment with phonophoresis demonstrated being the method more efficient, due the high birefringence, revealing the best organization and aggregation of collagen fibers. These findings allow conclude that the therapeutic ultrasound stimulate the acceleration of tissue repair process and induce the transdermal delivery of hydrocortisone 10% in a therapeutic concentration

O colágeno é a forma funcional de um oligômero biológico, cujos monômeros são aminoácidos quirais. Tecidos ricos em colágeno são estruturas opticamente anisotrópicas, birrefringentes e não-lineares. O objetivo deste trabalho foi caracterizar o colágeno tipo I não irradiado e após irradiação com laser de He-Ne polarizado, utilizando a microscopia de polarização para investigação da birrefringência, e a geração de segundo harmônico (GSH) para análise da susceptibilidade não-linear. Doze ratos Wistar foram divididos em quatro grupos, de acordo com as idades: 34, 48, 62 e 76 dias. Os grupos receberam, respectivamente, 1; 5; 9 e 13 irradiações de D= 1J/cm2, durante 46s, no tendão de Aquiles que, aleatoriamente, foi escolhido ser o direito ou esquerdo. Os animais foram então sacrificados e os tendões extraídos para a preparação das amostras. Para a microscopia de polarização foram obtidos cortes com 8μm de espessura, e as birrefringências de forma e intrínseca foram avaliadas. Para a GSH foi utilizado um laser de Ti:Safira (150fs) com 76MHz de taxa de repetição, diâmetro do feixe φ= 40μm, comprimento de onda central λ= 800nm e Δλ= 10nm e Pp= 110mW. Um polarizador linear foi posicionado no caminho do feixe. Duas objetivas foram utilizadas para focalizar e coletar a radiação incidente e emergente da amostra, respectivamente. Um analisador, também linear, foi introduzido logo após a objetiva coletora. Um filtro absorvedor na faixa infravermelha do espectro eletromagnético, mas transmissor na faixa azul, foi utilizado para garantir que apenas λ= 400nm era medido. A razão, ρ, entre dois tensores de hiperpolarizabilidade independentes foi estudada. As amostras irradiadas apresentaram maior birrefringência (Δn) e maior susceptibilidade não-linear (ρ), em comparação com as não irradiadas. Estes resultados indicam que o laser de He-Ne polarizado alinha as fibrilas de colágeno ao longo eixo do tendão. / The collagen is the functional form of a biological oligomer whose monomers are chiral amino acids. Tissues filled up of collagen are anisotropic optically structures, birefringent and nonlinear. The purpose of this study was characterizing nonirradiated and polarized He-Ne laser irradiated type I collagen using polarized light microscopy to investigate the birefringence and the second harmonic generation (SHG) to analyze the nonlinear susceptibility. Twelve Wistar rats were alienated into four groups according to the ages: 34, 48, 62 and 76 days. The groups received, respectively, 1; 5; 9; and 13 irradiations of D= 1J/cm2 during 46s on Achilles tendon, which was chosen randomly as right or left. Thereafter, the animals were sacrificed and the tendons were extracted to prepare the specimens. For polarized light microscopy, eight-μm sections were obtained to evaluate the form and intrinsic birefringences. For SHG, it was used a Ti:Safira (150fs) laser at a repetition rate of 76MHz, beam diameter of φ= 40μm, wavelength of λ= 800nm and Δλ= 10nm and Pp= 110mW. The beam passed through a linear polarizer and two microscope objectives were used to focalize and collect the incident and emergent radiation, respectively. A second linear polarizer was placed after of collecting objective. An infrared absorber and blue transmitter filter was used a sure that only λ= 400nm was measured. The ratio, ρ, between two hyperpolarizability tensors was studied. The irradiated samples presented higher birefringence (Δn) and nonlinear susceptibility (ρ) when compared to nonirradiated samples. These results indicate that a polarized He-Ne laser aligns the collagen fibrils to the long tendon axis.