L'inscription laser directe est un domaine de recherche en croissance depuis ces deux dernières décennies, fournissant un moyen efficace et robuste pour inscrire directement des structures en trois dimensions (3D) dans des matériaux transparents tels que des verres en utilisant des impulsions laser femtosecondes. Cette technique présente de nombreux avantages par rapport à la technique de lithographie, qui se limite à la structuration en deux dimensions (2D) et implique de nombreuses étapes de fabrication. Cela rend la technique d’inscription laser direct bien adaptée aux nouveaux procédés de fabrication. Généralement, l’inscription laser dans les verres induit des changements physiques tels qu'un changement permanent de l'indice de réfraction localisé. Ces modifications ont été classés en trois types distincts : (Type I, Type II et Type III). Dans ce travail, nous présentons un nouveau type de changement d'indice de réfraction, appelé type A qui est basé sur la création d’agrégats d'argent photo-induit. En effet, dans des verres dans lesquels sont incorporés des ions argent Ag+, lors de leurs synthèses, l’inscription laser directe induit la création d’agrégats d’argent fluorescents Agmx+ au voisinage du voxel d’interaction. Ces agrégats modifient localement les propriétés optiques comme : la fluorescence, la non-linéarité et la réponse plasmonique du verre. Ainsi, différents guides d'ondes, un séparateur de faisceau 50-50, ainsi que des coupleurs optiques ont été inscrits en se basant sur ce nouveau Type A et complétement caractérisés. D'autre part, une étude comparative entre les deux types de guides d'ondes (type A et type I) est présentée, tout en montrant qu’en ajustant les paramètres laser, il est possible de déclencher soit le Type I soit le Type A. Enfin, en se basant sur des guides d’ondes de type A inscrits proche de la surface du verre, un capteur d'indice de réfraction hautement sensible a été inscrit dans une lame de verre de 1 cm de long. Ce capteur miniaturisé peut présenter deux fenêtres de détection d’indice, ce qui constitue une première mondiale. Les propriétés des guides d'ondes inscrits dans ces verres massifs ont été transposées à des fibres en forme de ruban, du même matériau contenant de l'argent. Les résultats obtenus dans ce travail de thèse ouvrent la voie à la fabrication de circuits intégrés en 3D et de capteurs à fibre basés sur des propriétés optiques originales inaccessibles avec des guides d’onde de Type I standard. / Direct Laser Writing (DLW) has been an exponentially growing research field during the last two decades, by providing an efficient and robust way to directly address three dimensional (3D) structures in transparent materials such as glasses using femtosecond laser pulses. It exhibits many advantages over lithography technique which is mostly limited to two dimensional (2D) structuring and involves many fabrication steps. This competitive aspect makes the DLW technique suitable for future technological transfer to advanced industrial manufacturing. Generally, DLW in glasses induces physical changes such as permanent local refractive index modifications that have been classified under three distinct types: (Type I, Type II & Type III). In silver containing glasses with embedded silver ions Ag+, DLW induces the creation of fluorescent silver clusters Agmx+ at the vicinity of the interaction voxel. In this work, we present a new type of refractive index change, called type A that is based on the creation of the photo-induced silver clusters allowing the creation of new linear and nonlinear optical waveguides in silver containing glasses. Various waveguides, a 50-50 Y beam splitter, as well as optical couplers, were written based on type A modification inside bulk glasses and further characterized. On the other hand, a comparison study between type A and type I waveguides is presented, showing that finely tuning the laser parameters allows the creation of either type A or type I modification inside silver containing glasses. Finally, based on type A near-surface waveguides, a highly sensitive refractive index sensor is created in a 1 cm glass chip, which could exhibit a pioneer demonstration of double sensing refractive ranges. The waveguiding properties observed and reported in the bulk of such silver containing glasses were transposed to ribbon shaped fibers of the same material. Those results pave the way towards the fabrication of 3D integrated circuits and fiber sensors with original fluorescent, nonlinear and plasmonic properties that are not accessible using the standard type I modification

Dans cette thèse nous avons ajouté le contrôle du paramètre spectral pour donner plus de degré de liberté à l’instrument basé sur l’Imagerie par Résonance des Plasmons de Surface (SPRI), développant un système instrumental à interrogation angulo-spectrale. Pour valider notre travail, nous avons pris comme modèle d’étude un milieu diélectrique absorbant à unelongueur d’onde visible. La fonction diélectrique complexe est traitée par le modèle de Lorentz et la relation entre la partie réelle et imaginaire de l’indice optique est assurée par la relation de Kramers-Kronig. Nous avons commencé par injecter dans la cellule de mesure un colorant absorbant à 630 nm et mesuré la réflectivité angulo-spectrale avec ce milieu. Ensuite, un programme d’ajustement, que nous avons développé, a été utilisé pour le calcul inverse et la détermination des paramètres optiques à partir des données de l’expérience. Cet ajustement permet d’extraire la partie réelle et la partie imaginaire de l’indice de réfraction démontrant la possibilité d’applications de type spectroscopique. Nous avons également intégré successivement à la surface des molécules d’ADN marquées par différents chromophores pour voir l’effet de la position d’absorption sur la variation de réflectivité angulo-spectrale. En plus des milieux absorbants, nous avons fabriqué des réseaux diélectriques et métalliques et les avons intégrés à la surface du prisme. Les structures utilisées avaient une période de 250 nm et une épaisseur de 300 nm en PMMA. Cette condition nous a permis de voir un plasmon bandgap centré à 735 nm. Cette étude expérimentale est validée par une étude théorique en utilisant la méthode RCWA pour simuler la réponse des réseaux périodiques. / During this work we added the spectral parameter to the homemade Surface Plasmon Resonance Imaging (SPRI) instrument, developing an angulo-spectral instrumental system. To validate our set-up, we first used a dielectric medium absorbing in the visible spectral range as a model case. The complex dielectric function was treated by the Lorentz model and the relationship between the imaginary and the real part of the refractive index medium was calculated with the Kramers-Kronig relation. We started by injecting an absorbing dye at 630 nm in the microfluidic cell and then measured the angulo-spectral reflectivity. The experimental measurements were fitted with calculations issued from a newly developedprogram to extract the dielectric optical parameter from the experimental data. This fit calculates the imaginary and real part of the absorbing dielectric medium demonstrating the possibility for spectroscopic applications. We also integrated DNA molecules tagged with different chromophores to study the effect of the absorption wavelength on the surface plasmon angulo-spectral reflectivity variation. Furthermore, to illustrate the interest of the spectral parameter, one can integrate adielectric or metallic grating on the prism surface. Specifically, we fabricated a dielectric grating of PMMA with 250 nm period and 300 nm thickness. We observed plasmons bandgap located at 735 nm. This experimental study was in good agreement with a simulation obtained using a RCWA method based program.

O índice de refração não-linear n2 é o parâmetro chave da não-linearidade de terceira ordem em materiais ópticos. Um método simples, direto e sensível para medição do índice de refração não-linear (n2) é a técnica Z-scan proposta Sheik-Bahae et al 1. Nesse trabalho, um estudo sistemático quanto a esta técnica foi realizado. Utilizando a integral de difração de Fresnel-Kirchhoff, foi possível analisar a técnica investigando a influência do raio de abertura da íris. Foram obtidas expressões analíticas inéditas quando consideramos baixas não-linearidades induzidas por amostras finas. Esses resultados mostraram que o valor de n2 obtido é aproximadamente 36% maior do que n2 obtido por Sheik-Bahae para abertura linear de S=0,5, por exemplo.Extensões da técnica foram feitas, onde simulações para testar a viabilidade de medidas Z-scan no campo próximo e com dois feixes foram realizadas, de onde também foi possível encontrar resultados analíticos inéditos. Esses resultados teóricos foram testados tanto para feixe único quanto duplo em alguns experimentos, sendo obtido um bom acordo. Por fim, um novo método para medição do índice de refração não-linear não-degenerado foi proposto, em que é possível obter n2 no comprimento de onda do feixe de prova, num experimento com dois feixes. Esse resultado é importante uma vez que, em muitos casos, não é possível a realização de uma medida Z-scan convencional, devido ao fato da amostra não absorver o comprimento de onda do feixe de prova. Um resultado de n2 para rubi em 633nm foi obtido em bom acordo com resultados prévios da literatura, em que foram utilizadas técnicas de maior complexidade experimental. / The nonlinear refractive index n2 is the key parameter of the third order nonlinearity of optical materials. A simple, direct and sensitive measurement of nonlinear refractive index n2 is so-called Z-scan technique proposed by Sheik Bahae et al 1. In this work, a systematic study on this technique was performed. Based on Fresnel-Kirchhoff diffraction integral formula, it was possible to analyze the technique in order to investigate the influence of the apertures radius. We obtained unpublished analytical expressions when we consider small nonlinearities induced by thin samples. These results showed that the value of n2 obtained is about 36% larger than n2 obtained by Sheik-Bahae when the linear opening is 50%, for example.Extensions about the technique were made. Simulations were performed in order to test the feasibility of near-field Z-scan and two-color Z-scan measurements. Again it was also possible to find unpublished analytical results. The theoretical results were tested in some experiments and good agreement was found. Finally, a new method for measuring the nondegenerate refractive index was proposed. So, there is the possibility to obtain n2 at the wavelength of the probe beam in a two-color Z-scan experiment. This result is important since in many cases is impossible to perform a conventional z-scan measurement, due to the fact that the sample does not absorb the wavelength of the probe beam. A result of n2 for ruby at 633nm was obtained in good agreement with previous studies.

Neste trabalho estudamos uma nova classe de materiais ópticos não-lineares, os cristais orgânicos, que possuem potencial para muitas aplicação em dispositivos. Determinamos diferentes propriedades ópticas lineares e não-lineares de três cristais orgânicos: a l-alanina, a l-treonina e a l-lisina. Esses cristais de aminoácido foram escolhidos por apresentarem propriedades de geração de segundo harmônico (GSH) e por serem materiais nunca estudados sob o ponto de vista da óptica não-linear. Estudamos algumas das propriedades ópticas lineares fundamentais desses cristais biaxiais transparentes, pois deles dependem os fenômenos não-lineares sobre os quais são feitas intensas pesquisas. Determinamos as propriedades lineares como os espectros de absorção, os índices de refração, os eixo ópticos, velocidade de propagação da luz num meio anisotrópico e os limiares de dano por radiação. Posteriormente, determinamos as condições de casamento de fase, a eficiência de GSH, e a auto-modulação de fase. A GSH e a auto-modulação de fase pertencem, respectivamente, a processos não-lineares de segunda e de terceira-ordem. Para o estudo de muitas dessas propriedades foram desenvolvidas novas técnicas experimentais. Uma dessas novas técnicas, a varredura-Z oscilante, teve sensibilidade para determinar, pela primeira vez, o índice de refração não oscilante, vez, o índice de refração não linear desses cristais orgânicos. Além disso, como a todos os processos de caracterização envolveram a preparação de amostras, tivemos a oportunidade de criar procedimentos padrões para manipulação e utilização desses novos materiais. / In this work we studied a new class of nonlinear organic crystals that are potential candidates for devices application. We determined several linear and nonlinear optical properties of three organic crystals: l-alanine, l-threonine and l-lysine. These aminoacid. These aminoacid because their nonlinearities were never studied before. We characterized some of the fundamental linear optical properties of these biaxial transparent crystals, because they have influence on nonlinear phenomena that attracted a lot of research. We determined linear properties like absorption spectra, indices of refraction, optical axes, the light speed propagation in anisotropy media and the optical damage threshold. Subsequently, we determined the phase-matching condition for SHG, efficiency of the SHG and self-phase modulation. The SHG and self-phase modulation belongs, respectively, to the second-order and third-order nonlinear processes. To study several of these properties we had to develop some new experimental techniques. One of them, the oscillatory Z-scan, allows enough sensibility to determine, for the first time, the nonlinear refraction index of these organic crystals. Besides, as all these optical characterization involve the preparation of the samples, we had the opportunity to establishing standard procedures for manipulation of these new materials.

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

Objetivo: Em anisométropes, comparar os valores médios individuais dos componentes oculares de ambos os olhos (poder da córnea, profundidade da câmara anterior, poder equivalente do cristalino e comprimento axial), correlacionar as diferenças dos componentes oculares com as diferenças de refração de ambos os olhos; verificar a contribuição total e a seqüência geral de influência das variáveis na diferença refrativa; e identificar o menor número de fatores que contenham o mesmo grau de informações expressas no conjunto de variáveis que influenciam na diferença refrativa. Métodos: Realizou-se um estudo transversal analítico em população de 77 anisométropes de duas ou mais dioptrias, atendida no ambulatório de Oftalmologia do Hospital Universitário da Faculdade de Medicina Nilton Lins, Manaus, Amazonas. Os anisométropes foram submetidos à refração estática objetiva e subjetiva, ceratometria e biometria ultra-sônica A-scan. A análise dos dados foi feita por meio dos seguintes modelos estatísticos: análise univariada, multivariada, de regressão múltipla e fatorial. Resultados: Não houve diferenças significativas na comparação dos valores médios individuais dos componentes oculares entre os olhos. Houve correlação negativa média entre a diferença refrativa e a diferença de comprimento axial (r=-0,64) (P<0,01) e correlação negativa fraca entre a diferença refrativa e a diferença de poder do cristalino (r=-0,34) (p<0,01). As variáveis analisadas responderam, no seu conjunto, por 78% da variação total para a diferença refrativa. A seqüência geral de influência das variáveis na diferença refrativa foi a seguinte: comprimento axial, poder do cristalino, poder da córnea e profundidade da câmara anterior. Foram identificados três fatores para a diferença refrativa: a) fator 1 (refração, comprimento axial); b) fator 2 (profundidade da câmera anterior, poder da córnea) e c) fator 3 (poder do cristalino). Conclusões: O estudo conduzido em 77 indivíduos com anisometropias variando de 2,00 a mais de 19,00 dioptrias, realizado para avaliar a influência dos componentes oculares, mostrou que o comprimento axial foi o principal fator causador das anisometropias, seguido pelo cristalino que contribuiu menos, depois pela córnea e profundidade da câmara anterior, com contribuições ainda menores. A investigação sugere falência no mecanismo adaptativo normal em anisometropia, o que poderia produzir não só descontrole do alongamento do comprimento axial (fator 1), mas também falência no controle do aplanamento da córnea e do aprofundamento da câmara anterior (fator 2) e no achatamento do cristalino (fator 3). / Purpose: To compare the individual means of ocular components of both eyes (corneal power, anterior chamber depth, crystalline lens power and axial length) in patients with anisometropia; to correlate the differences of the ocular components with refractive differences in both eyes; to verify total contribution and the sequence of influence that variables have in refractive differences, and to identify the smallest number of factors that contain the same level of information expressed in the set of variables that influence refractive difference. Methods: An analytical transversal study was carried out in 77 patients with anisometropia of two or more dioptres seen at the Ophthalmologic Clinic, University Hospital, Medical School Nilton Lins, Manaus, Amazon state. All participants were submitted to ophthalmologic exam which included objective and subjective cycloplegic refractometry, keratometry and ultrasonic biometry. Data analysis comprised the following statistical models: univariate, multivariate, multiple and factorial regression analyses. Results: There were no significant differences in the comparison of the individual means of the ocular components. There was negative correlation between refractive difference and difference of axial length (r=- 0.64; p<0.01) and weak negative correlation between refractive difference and crystalline lens power difference (r=-0.34; p< 0.01). The analyzed variables amounted to 78% of the total variation of refractive difference. The general sequence of variables influencing refractive difference was: axial length, crystalline lens power, cornea power, and anterior chamber depth. There were three factors identified for refractive differences: a) factor 1 (refraction, axial length); b) factor 2 (anterior chamber depth, cornea power), and c) factor 3 (crystalline lens power). Conclusions: Seventy-seven cases of anisometropia ranging from 2,00 to over 19,00 dioptres, examined for the individual components of refraction, showed that axial length was the major causative factor; crystalline lens have contributed less, followed by cornea and anterior chamber length. This study has suggested deficit of the normal adaptive mechanism in anisometropia that could produce not only axial elongation (factor 1), but also failure to control flattening of the cornea, deepening of the anterior chamber length (factor 2) and flattening of crystalline lens (factor 3).

Propriedades ópticas, magnéticas e elásticas de duas liomesofases nemáticas tipo I (decilsulfato de sódio/água/ n-decanol e laurato de potássio/água/cloreto de potássio) e urna tipo II (decilsulfato de sódio/água/n-decanol /sulfato de sódio) são estudadas. Nas investigações de tais propriedades as medidas realizadas e instrumentação/meios utilizados foram os seguintes: medidas de sinais ópticos, texturas e temperaturas de transições de fases foram obtidas com auxilio de um microscópio petrográfico com temperatura controlada na platina; medidas de índices de refração e birrefringências obtiveram- se com adaptações do refratômetro de Pulfrich; medidas de susceptibilidades diamagnéticas direcionais foram realizadas com adaptações ao magnetômetro de amostra vibrante; medidas de constantes elásticas foram obtidas com auxilio de uma montagem especial. São realizados cálculos para as susceptibilidades diamagnéticas direcionais e respectivas anisotropias moleculares para alcanos, álcoois e anfifilicos de interesse em liornesofases . Da comparação entre as anisotropias moleculares calculadas e as medidas em liomesofases correspondentes, infere-se que o ordenamento molecular de anfifilicos, nas mesofases, deve ser alto. O método de Kirkwood, que permite correlacionar polarizabilidade elétrica com a susceptibilidade diamagnética molecular média em substâncias puras, é estendido e adaptado a misturas complexas, criando assim urna promissora perspectiva de correlação entre as medidas ópticas e magnéticas em liomesofases. Evidências experimentais diretas, da aplicabilidade da teoria do continuo para termo trópicos às liomesofases, são apresentadas. / The optical, magnetic and elastic properties of three nematic lyomesophases are studied. Two are type I (Na decyl sulfate/ water/n- decanol and K laurate/water/K chloride) and one type II (Na decyl sulfate/water/n- decano l/Na sulfate). To measure these properties we used the following equipment : texture and optical sign were observed by optical microscopy with temperature controlled, hot and cold, stages; refractive indices were measured in an adapted Pulfrich refratometer; the individual elements of the diamagnetic susceptibility tensor were measured with a vibrating sample magnetometer; the elastic constants were measured using the Frederikzs transition in a special experimental set-up. Starting from the concept of localized magnetic susceptibilities, molecular anisotropies were calculated for saturated hydrocarbons , alcohols and amphiphilic compounds, which are of interest for lyomesophases. Comparing these results with the experimentally measured anisotropies of the lyomesophases it is possible to conclude that a high degree of molecular order is present in the nematic amphiphilic systems. The Kirkwood method is extended and adapted for complex mixtures. The use of this method opens new perspectives for exploring the correlation between the molecular polarizability and the mean diamagnetic susceptibility.

Objetivo: Em anisométropes, comparar os valores médios individuais dos componentes oculares de ambos os olhos (poder da córnea, profundidade da câmara anterior, poder equivalente do cristalino e comprimento axial), correlacionar as diferenças dos componentes oculares com as diferenças de refração de ambos os olhos; verificar a contribuição total e a seqüência geral de influência das variáveis na diferença refrativa; e identificar o menor número de fatores que contenham o mesmo grau de informações expressas no conjunto de variáveis que influenciam na diferença refrativa. Métodos: Realizou-se um estudo transversal analítico em população de 77 anisométropes de duas ou mais dioptrias, atendida no ambulatório de Oftalmologia do Hospital Universitário da Faculdade de Medicina Nilton Lins, Manaus, Amazonas. Os anisométropes foram submetidos à refração estática objetiva e subjetiva, ceratometria e biometria ultra-sônica A-scan. A análise dos dados foi feita por meio dos seguintes modelos estatísticos: análise univariada, multivariada, de regressão múltipla e fatorial. Resultados: Não houve diferenças significativas na comparação dos valores médios individuais dos componentes oculares entre os olhos. Houve correlação negativa média entre a diferença refrativa e a diferença de comprimento axial (r=-0,64) (P<0,01) e correlação negativa fraca entre a diferença refrativa e a diferença de poder do cristalino (r=-0,34) (p<0,01). As variáveis analisadas responderam, no seu conjunto, por 78% da variação total para a diferença refrativa. A seqüência geral de influência das variáveis na diferença refrativa foi a seguinte: comprimento axial, poder do cristalino, poder da córnea e profundidade da câmara anterior. Foram identificados três fatores para a diferença refrativa: a) fator 1 (refração, comprimento axial); b) fator 2 (profundidade da câmera anterior, poder da córnea) e c) fator 3 (poder do cristalino). Conclusões: O estudo conduzido em 77 indivíduos com anisometropias variando de 2,00 a mais de 19,00 dioptrias, realizado para avaliar a influência dos componentes oculares, mostrou que o comprimento axial foi o principal fator causador das anisometropias, seguido pelo cristalino que contribuiu menos, depois pela córnea e profundidade da câmara anterior, com contribuições ainda menores. A investigação sugere falência no mecanismo adaptativo normal em anisometropia, o que poderia produzir não só descontrole do alongamento do comprimento axial (fator 1), mas também falência no controle do aplanamento da córnea e do aprofundamento da câmara anterior (fator 2) e no achatamento do cristalino (fator 3). / Purpose: To compare the individual means of ocular components of both eyes (corneal power, anterior chamber depth, crystalline lens power and axial length) in patients with anisometropia; to correlate the differences of the ocular components with refractive differences in both eyes; to verify total contribution and the sequence of influence that variables have in refractive differences, and to identify the smallest number of factors that contain the same level of information expressed in the set of variables that influence refractive difference. Methods: An analytical transversal study was carried out in 77 patients with anisometropia of two or more dioptres seen at the Ophthalmologic Clinic, University Hospital, Medical School Nilton Lins, Manaus, Amazon state. All participants were submitted to ophthalmologic exam which included objective and subjective cycloplegic refractometry, keratometry and ultrasonic biometry. Data analysis comprised the following statistical models: univariate, multivariate, multiple and factorial regression analyses. Results: There were no significant differences in the comparison of the individual means of the ocular components. There was negative correlation between refractive difference and difference of axial length (r=- 0.64; p<0.01) and weak negative correlation between refractive difference and crystalline lens power difference (r=-0.34; p< 0.01). The analyzed variables amounted to 78% of the total variation of refractive difference. The general sequence of variables influencing refractive difference was: axial length, crystalline lens power, cornea power, and anterior chamber depth. There were three factors identified for refractive differences: a) factor 1 (refraction, axial length); b) factor 2 (anterior chamber depth, cornea power), and c) factor 3 (crystalline lens power). Conclusions: Seventy-seven cases of anisometropia ranging from 2,00 to over 19,00 dioptres, examined for the individual components of refraction, showed that axial length was the major causative factor; crystalline lens have contributed less, followed by cornea and anterior chamber length. This study has suggested deficit of the normal adaptive mechanism in anisometropia that could produce not only axial elongation (factor 1), but also failure to control flattening of the cornea, deepening of the anterior chamber length (factor 2) and flattening of crystalline lens (factor 3).

Propriedades ópticas, magnéticas e elásticas de duas liomesofases nemáticas tipo I (decilsulfato de sódio/água/ n-decanol e laurato de potássio/água/cloreto de potássio) e urna tipo II (decilsulfato de sódio/água/n-decanol /sulfato de sódio) são estudadas. Nas investigações de tais propriedades as medidas realizadas e instrumentação/meios utilizados foram os seguintes: medidas de sinais ópticos, texturas e temperaturas de transições de fases foram obtidas com auxilio de um microscópio petrográfico com temperatura controlada na platina; medidas de índices de refração e birrefringências obtiveram- se com adaptações do refratômetro de Pulfrich; medidas de susceptibilidades diamagnéticas direcionais foram realizadas com adaptações ao magnetômetro de amostra vibrante; medidas de constantes elásticas foram obtidas com auxilio de uma montagem especial. São realizados cálculos para as susceptibilidades diamagnéticas direcionais e respectivas anisotropias moleculares para alcanos, álcoois e anfifilicos de interesse em liornesofases . Da comparação entre as anisotropias moleculares calculadas e as medidas em liomesofases correspondentes, infere-se que o ordenamento molecular de anfifilicos, nas mesofases, deve ser alto. O método de Kirkwood, que permite correlacionar polarizabilidade elétrica com a susceptibilidade diamagnética molecular média em substâncias puras, é estendido e adaptado a misturas complexas, criando assim urna promissora perspectiva de correlação entre as medidas ópticas e magnéticas em liomesofases. Evidências experimentais diretas, da aplicabilidade da teoria do continuo para termo trópicos às liomesofases, são apresentadas. / The optical, magnetic and elastic properties of three nematic lyomesophases are studied. Two are type I (Na decyl sulfate/ water/n- decanol and K laurate/water/K chloride) and one type II (Na decyl sulfate/water/n- decano l/Na sulfate). To measure these properties we used the following equipment : texture and optical sign were observed by optical microscopy with temperature controlled, hot and cold, stages; refractive indices were measured in an adapted Pulfrich refratometer; the individual elements of the diamagnetic susceptibility tensor were measured with a vibrating sample magnetometer; the elastic constants were measured using the Frederikzs transition in a special experimental set-up. Starting from the concept of localized magnetic susceptibilities, molecular anisotropies were calculated for saturated hydrocarbons , alcohols and amphiphilic compounds, which are of interest for lyomesophases. Comparing these results with the experimentally measured anisotropies of the lyomesophases it is possible to conclude that a high degree of molecular order is present in the nematic amphiphilic systems. The Kirkwood method is extended and adapted for complex mixtures. The use of this method opens new perspectives for exploring the correlation between the molecular polarizability and the mean diamagnetic susceptibility.

Ce travail de thèse a été consacré à la photostructuration d’une matrice polymère de type acrylate contenant des points quantiques CdSe/ZnS (QDs) par l’enregistrement de réseaux. La diffusion photoinduite des nanocristaux semi-conducteurs a tout d’abord été mise en évidence par l’utilisation d’un montage permettant d’irradier sur une seule ligne, et par l’émission de fluorescence des QDs utilisée ici comme sonde de déplacement. Ensuite, pour comprendre l’augmentation de la modulation d’indice de réfraction, et par conséquent du rendement de diffraction des réseaux enregistrés dans ces matériaux composites, nous avons mis en place une approche physico-chimique. Celle-ci nous a permis de corréler les modifications chimiques et les propriétés physiques du réseau. En effet, nous avons montré que l’ajout de points quantiques influence la cinétique de polymérisation ; la vitesse de consommation du photosensibilisateur et de conversion des monomères diminuent. Cette diminution permet une meilleure diffusion des espèces au sein de la matrice. Donc, le ralentissement de la cinétique de photopolymérisation et la répartition spatiale des QDs contribuent à un accroissement de la modulation d’indice de réfraction des réseaux enregistrés. / This work is devoted to the photostructuration of an acrylate polymer matrix with dispersed CdSe/ZnS quantum dots (QDs) upon grating exposure. The photo-induced diffusion of semiconductor nanocrystals is proved by the use of a "one line irradiation" set up and by the emission of the QDs fluorescence, used here as a probe of displacement. Then, in order to understand the increase of the refractive index modulation, and so, of the diffraction efficiency of the recorded patterns in the composite materials, we apply a physico-chemical approach. This one allows correlating the chemical modifications to the physical properties of the gratings. Indeed, we show that the addition of QDs influences the kinetics of polymerization ; the rate of the photo-initiator consumption, and that of the monomer conversion decrease. This decrease favors the diffusion ofthe species inside the matrix. Therefore, the slowing down of the kinetics of the photopolymerization and the spatial distribution of QDs contribute to the enhancement of the refractive index modulation of the recorded gratings.