Neste trabalho apresentamos resultados de birrefringência opticamente induzida via absorção de um e dois fótons em filmes casting de poli (metil metacrilato) (PMMA), contendo uma nova série de compostos azoaromáticos chamados de corantes Salen, os quais podem ser usados em aplicações de memória óptica. Para a birrefringência opticamente induzida por um fóton, foi necessário um tempo de escrita maior para os compostos com metal na estrutura em comparação com o composto Salen que não contém metal, provavelmente devido a agregações do grupo azoaromático na estrutura do polímero diminuindo a mobilidade molecular. Além disso, como uma novidade em memórias ópticas deste tipo, birrefringência opticamente induzida por dois fótons pôde ser realizada nos filmes de Salen, o que pode permitir sua aplicação em memória óptica tridimensional. / In this work we present the one- and two-photon optically induced birefringence in cast films of amorphous poly(methyl methacrylate) (PMMA), containing a new series of organometallic azoaromatic compounds, referred to as Salen dyes, which may be used in optical storage applications. For the one-photon optically induced birefringence, longer writing times were required for the organometallic compounds in comparison with the nonmetal one, probably due to the higher degree of aggregation in the azoaromatic moieties that precludes molecular orientation. Furthermore, as a novelty concerning optical storage, two-photon optically induced birefringence could be achieved in the Salen dyes guest-host films, which allows their application in three-dimensional optical memories.

La estructura y componentes del ojo humano hacen que los cambios que se producen sobre el estado de polarización de la luz que emerge de él, tras realizar un doble paso y sufrir una reflexión en la retina, sean complejos y a priori poco predecibles. Esos cambios pueden influir en los resultados obtenidos con dispositivos que analizan la luz reflejada en la retina. Para conocer mejor los cambios que el ojo origina sobre un haz que lo atraviesa y los fenómenos a los que da lugar, se ha llevado a cabo un estudio de la calidad de imagen retiniana en función de los estados de polarización, así como un estudio espacial de los distintos parámetros de polarización a partir del cálculo de matrices de Mueller. Teniendo como base el método de doble paso, se ha diseñado y construido un polarímetro de imagen que utiliza retardadores variables de cristal líquido en los brazos generador y analizador. Con este dispositivo se han registrado series de dieciséis imágenes de doble paso correspondientes a las combinaciones independientes de estados de polarización de entrada y salida. Los resultados para varios sujetos muestran que la calidad de imagen depende en gran medida del estado de polarización de salida. Sin embargo, la influencia de la polarización de entrada, calculada usando matrices de Mueller espacialmente resueltas, juega un papel poco significativo. Por otra parte, el estudio polarimétrico de las imágenes de doble paso muestra que (1) la parte central de las imágenes tiene un grado de polarización del 80% frente a un 25% en la periferia; (2) el retardo introducido depende del observador, aunque la birrefringencia que presenta el ojo es lineal; (3) el dicroísmo es coherente con la longitud de onda empleada y (4) el valor de la polarizancia indica la existencia de cierta birrefringencia circular. / The structure and components of the human eye make changes produced on the polarization state of the light emerging from it after a double-pass through ocular media and a reflection in the retina be complicated and hardly predectible. Those changes can influence on the results obtained with any device analyzing the light reflected in the retina. A study of the retinal image quality as a function of the polarization state has been performed. A spatially resolved polarimetric study of different polarization parameters using Mueller-matrices was also performed. An imaging polarimeter adapted to an ophthalmoscopic double-pass apparatus using two ellectronically controlled liquid-crystal variable retarders has been developed. Series of sixteen double-pass images corresponding to independent combinations generator-analyzer have been recorded. Results obtained for several subjects show that the estimation of the image quality depends strongly on the polarization state in the exit pathway. However, the influence of the entrance polarization, calculated using spatially resolved Mueller-matrices is nearly negligible. On the other hand, the polarimetric study of double-pass images shows that (1) the light forming the central part of the images presents a degree of polarization of 80% while this is reduced to around 25% for the light in the skirts; (2) the retardation introduced by the eye in a double-pass is quite dependent on observers, although the birefringence is linear; (3) the dicroism is coherent with the wavelength used, and (4) the value of the polarizance indicates the existency of circular birrefringence.

Birefringence measurements are of great importance in a plethora of applications spanning from biology to optical communications. Birefringence measurements of nerve-fiber layers have emerged as an important diagnostic technique for early detection of glaucoma. Stress-induced birefringence in optical devices affects their performances by causing Polarization-Mode Dispersion (PMD) and Polarization-Dependent Loss (PDL). Stress-relaxation constitutes a key phenomenon governing the fabrication of some optical devices such as Long-Period Fiber Gratings (LPFGs). This drives the need to develop accurate optical instrumentation techniques to evaluate form and stress-induced birefringence. This thesis deals with the development of new high-accuracy techniques for the characterization of stress-induced birefringence in optical devices. The new Two-Waveplate Compensator (TWC) technique is presented for single-point retardation measurements. It is extensively compared theoretically and experimentally to existing techniques including the Snarmont and Brace-Khler techniques. The Phase-Stepping Two-Waveplate Retarder (PSTWR) is also presented for high-accuracy measurements of retardation magnitude and orientation. The Colorimetry-Based Retardation Method (CBRM) is presented to measure retardation using white-light interference colors. The technique is implemented using a polarization microscope and a spectrophotometer. The TWC and the Brace-Khler methods are implemented for full-field retardation measurements using a polarization microscope. Their accuracies are quantified over the entire field-of-view for small retardations. They are applied to the stress-induced birefringence imaging of LPFGs and polymer pillar waveguides. The TWC technique achieves an accuracy of 0.06 nm and a sensitivity of 0.07 nm. The Brace- Khler technique achieves an accuracy of 0.04 nm and a sensitivity of 0.09 nm. The spatial resolution of both techniques is 0.45 and #61549;m. A Fourier-based algorithm is presented to compute the inverse Abel transform relating the retardation to the axial residual stress profile in optical fibers. It is used to calculate the residual stress profiles of single-mode fibers from full-field retardation measurements with the TWC and Brace- Khler techniques. The stress profiles computed in this work are in very good agreement with previously reported results in the literature. The TWC technique produces the most accurate stress measurements. The TWC technique is used to investigate the stress-relaxation phenomena in LPFGs fabricated using CO2 laser irradiations.

Polarized light has the ability to increase the specificity of the investigation of biomedical samples and is finding greater utilization in the fields of medical diagnostics, sensing, and measurement. In particular, this dissertation focuses on the application of polarized light to address a major obstacle in the development of an optical based polarimetric non-invasive glucose detector that has the potential to improve the quality of life and prolong the life expectancy of the millions of people afflicted with the disease diabetes mellitus. By achieving the mapping of the relative variations in rabbit corneal birefringence, it is hoped that the understanding of the results contained herein will facilitate the development of techniques to eliminate the effects of changing corneal birefringence on polarimetric glucose measurement through the aqueous humor of the eye. This dissertation also focuses on the application of polarized light to address a major downside of cardiovascular biomechanics research, which is the utilization of toxic chemicals to prepare samples for histological examination. To this end, a polarization microscopy image processing technique is applied to non-stained cardiovascular samples as a means to eliminate, for certain cardiac samples, the necessity for staining using toxic chemicals. The results from this work have the potential to encourage more investigators to join the field of cardiac biomechanics, which studies the remodeling processes responsible for cardiovascular diseases such as myocardial infarct (heart attacks) and congestive heart failure. Cardiovascular disease is epidemic, particularly amongst the population group older than 65 years, and the number of people affected by this disease is expected to increase appreciably as the baby boomer generation transitions into this older, high risk population group. A better understanding of the responsible mechanisms for cardiac tissue remodeling will facilitate the development of better prevention and treatment regimens by improving the early detection and diagnosis of this disease.

An Enhanced Polarization-Sensitive Swept Source Optical Coherence Tomography (EPS-SS-OCT) instrument for high sensitivity cross-sectional imaging of Retinal Nerve Fiber Layer (RNFL) has been designed, constructed, and verified. The instrument is capable of measuring the thickness and birefringence of the RNFL. Birefringence change of the RNFL could serve as an early indicator of glaucoma. The associated image processing methods for completely automated, time efficient algorithm to segment the RNFL in images of the human retina recorded by the EPS-SS-OCT. Detected RNFL boundaries are used to compute peripapillary thickness maps. Numerical algorithms to compute the birefringence of the detected RNFL layer are presented along with the associated phase retardation and birefringence peripapillary maps. Glaucoma affects the vitality of retinal ganglion cell axons in the retinal nerve fiber layer (RNFL) and may be clinically detected through a change in RNFL birefringence. Comprehensive peripapillary maps of healthy and glaucoma suspect human RNFL birefringence were constructed using EPS-SS-OCT. Presence of macrophages is a hallmark of several retinal diseases such as drusen and age related macular degeneration. Application of photothermal Optical Coherence Tomography (OCT) to detect macrophages in ex vivo arteries which have engulfed nanoclusters of gold coated iron oxide (nanorose) is reported. Nanorose engulfed by macrophages in arteries absorb incident laser (800nm) energy and cause optical pathlength (OP) variation which is measured using photothermal OCT. OP variation in polydimethyl siloxane tissue phantoms containing varying concentrations of nanorose match values predicted from nanoparticle and material properties. Measurement of OP variation in arteries in response to laser excitation provides an estimate of nanorose concentration in arteries 2.5x109 particles/ml. OP variation in nanoparticle containing artery sections and tissue phantoms taking up nanorose has a different magnitude and profile from that observed in control aorta and phantoms without macrophages and is consistent with macrophage presence as identified with RAM-11 histology staining. Our results suggest that tissue regions with macrophages taking up nanorose can be detected using photothermal OCT. / text

Kietojo kūno optikos mokslinėje laboratorijoje buvo išmatuoti mūsų išaugintų SbSI, TlInS2 ir TGS kristalų dvejopo lūžio priklausomybė nuo temperatūros. Eksperimentinis dvejopo lūžio priklausomybės nuo temperatūros tyrimas leido nustatyti TGS, TlInS2 ir SbSI kristalų fazinių virsmų temperatūrą. Teoriškai, tankio funkcionalo teorijos metodu (DFT), buvo apskaičiuoti SbSI kristalo lūžio rodikliai paraelektrinėje ir feroelektrinėje fazėse. Taip pat skaičiuotas dvejopas lūžis feroelektrinio fazinio virsmo srityje. Teoriniai dvejopo lūžio skaičiavimų rezultatai palyginti su eksperimentiniais matavimų rezultatais. / In Solid State Science Laboratory we measured birefringence on temperature of grown SbSI, TlInS2 and TGS crystals. The measurement of birefringence helps to evaluate the ferroelectric phase transition of TGS, TlInS2 ir SbSI crystals. Refractive indices of SbSI crystal in paraelectric and ferroelectric phase we investigated by DFT method with program Wien2k. The theoretical results of birefringence were compared with experimental results.

Made available in DSpace on 2014-06-11T19:27:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-20Bitstream added on 2014-06-13T19:35:04Z : No. of bitstreams: 1 silva_ml_me_bauru.pdf: 1014691 bytes, checksum: d6234b7cfd38238526074b3a223731a8 (MD5) / Neste trabalho investigaram-se a fabricação dos filmes de Langmuir e de filmes Langmuir-Blodgett (LB) mistos obtidos do azopolímero poli(metacrilato de lauroila-cometacrilato de DR1) com estearato de cádmio (StCd). A fabricação dos filmes LB desse azopolímero somente foi possível utilizando-se o StCd como suporte molecular. A caracterização espectroscópica dos filmes LB foi feita através de espectroscopia de absorção no UV-Visível e no infravermelho. As medidas de birrefringência fotoinduzida dos filmes LB mistos do azopolímero com StCd foram feitas em função do tempo durante a formação da birrefringência e no decaimento após a luz de excitação ter sido desligada. Os resultados experimentais obtidos nas medidas mostraram que a amplitude máxima da birrefringência obtida durante a excitação aumenta com a intensidade da luz de excitação e o número de camadas dos filmes LB. Foi também estudada a dinâmica da formação e do decaimento determinando-se as constantes de tempo dos processos de orientação usando funções biexponenciais do modelo de Sekkat / Fabrication of Langmuir and Langmuir-Blodgett (LB) mixed films of poly(lauroyl-methacrylate co-DR1 methacrylate) and cadmium stearate (CdSt) were investigated. The fabrication of LB films from this azopolymer was achieved only if CdSt molecular support is used. Spectroscopic characterization of films were performed by means of UV-Vis and infrared measurements. Photoinduced birefringence measurements of LB mixed films of azopolymer with CdSt were performed as function of time during the buildup of the birefringence and the decay after turning off the excitation light. Experimental results showed that the maximum birefringence achieved during the light excitation increased with the number of layers of the LB film and light intensity. Photoinduced birefringence dynamics was also investigated during the buildup and decay aiming to determine the time constants of bi-exponential functions given by the Sekkat model

Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-03Bitstream added on 2014-06-13T19:58:18Z : No. of bitstreams: 1 anami_lc_me_sjc.pdf: 782156 bytes, checksum: 4212a8739cd4cbb0bd4d24b494cb4a94 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi avaliar a localização e distribuição das tensões geradas ao redor de implantes com pilares protéticos de diferentes conexões cone Morse através da análise fotoelástica (AFE) e do método dos elementos finitos (MEF). Para o MEF, implante e pilares protéticos de diferentes conexões cone Morse (hexagonado e sólido) foram digitalizados pela técnica da microtomografia computadorizada e, com auxílio de softwares computacionais foi realizada a modelagem da malha tridimensional e o carregamento dos objetos. Foi realizada a caracterização das propriedades mecânicas da resina fotoelástica. Foram simulados blocos com propriedades mecânicas de osso cortical e trabecular e de resina fotoelástica. A AFE foi realizada a partir de blocos de resina fotoelástica onde foram incluídos os implantes aparafusados aos diferentes pilares protéticos. Estes blocos foram confeccionados a partir de um bloco prototipado do modelo utilizado no MEF. Os corpos-deprova foram imersos em um recipiente com óleo mineral e o conjunto foi observado no polariscópio circular com dispositivo de aplicação de cargas acoplado e recebendo a mesma carga, em sentido e posição iguais. Foi feita análise descritiva para as imagens obtidas em ambas as metodologias onde observou-se que: as imagens obtidas no MEF apresentaram distribuição de tensões bastante similar entre os dois modelos com diferentes pilares protéticos. Foram observadas diferenças entre a distribuição das tensões em blocos ósseo e de resina; As imagens obtidas na AFE se assemelharam às obtidas em MEF com bloco de resina. As imagens da AFE também foram analisadas quantitativamente, por comparação a valores atribuídos às franjas. A concordância interobservadores foi conferida pelo teste de Dahlberg. Concluiu-se que o Pilar Sólido transfere cargas mais homogeneamente para o osso adjacente ao implante... / The goal of this study was to evaluate the location and distribution of stresses generated around implants with different Morse taper connections abutments by photoelastic (PA) and finite element analysis (FEA). For FEA, implant and abutments with different Morse taper connections (hexagonal and solid) were scanned by computerized microtomography technique. The tridimensional mesh was modeled and the objects were loaded with the help of computer software. Photoelastic resin was characterized by mechanical properties. Trabecular and cortical bone and photoelastic resin blocks were simulated with their respective mechanical properties. The PA was performed with photoelastic resin blocks where implants were included and the different abutments were bolted. These blocks were made from a prototyped block of model used in FEA. Specimens were immersed in a mineral oil container and it was observed in the circular polariscope with the application device attached, where loads were received on same charge, on equal direction and position. Images obtained in both methodologies were descriptively analyzed where it was that: FEA images showed very similar stress distribution between two models with different abutments. Differences were observed between stress distribution in bone and resin blocks; PA images resembled those obtained on resin block FEA. PA images were also quantitatively analyzed by comparing the values assigned to fringes. Inter-observer agreement was given by Dahlberg test. It was concluded that solid abutment distributes loads more evenly to bone adjacent to implant compared with hexagonal abutment, for both analysis methods employed. Among the methodologies employed, it was observed that the PA has generated very similar results to those obtained in FEA with resin block, but different to those obtained in FEA when the clinical condition of the bone block was simulated

Made available in DSpace on 2014-10-09T12:46:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:48Z (GMT). No. of bitstreams: 1 08357.pdf: 3145355 bytes, checksum: e97667e5f2c069c9a76dad1d729d7c6c (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: José Alberto Giacometti / Banca: José Leonil Duarte / Banca: Neri Alves / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Neste trabalho investigaram-se a fabricação dos filmes de Langmuir e de filmes Langmuir-Blodgett (LB) mistos obtidos do azopolímero poli(metacrilato de lauroila-cometacrilato de DR1) com estearato de cádmio (StCd). A fabricação dos filmes LB desse azopolímero somente foi possível utilizando-se o StCd como suporte molecular. A caracterização espectroscópica dos filmes LB foi feita através de espectroscopia de absorção no UV-Visível e no infravermelho. As medidas de birrefringência fotoinduzida dos filmes LB mistos do azopolímero com StCd foram feitas em função do tempo durante a formação da birrefringência e no decaimento após a luz de excitação ter sido desligada. Os resultados experimentais obtidos nas medidas mostraram que a amplitude máxima da birrefringência obtida durante a excitação aumenta com a intensidade da luz de excitação e o número de camadas dos filmes LB. Foi também estudada a dinâmica da formação e do decaimento determinando-se as constantes de tempo dos processos de orientação usando funções biexponenciais do modelo de Sekkat / Abstract: Fabrication of Langmuir and Langmuir-Blodgett (LB) mixed films of poly(lauroyl-methacrylate co-DR1 methacrylate) and cadmium stearate (CdSt) were investigated. The fabrication of LB films from this azopolymer was achieved only if CdSt molecular support is used. Spectroscopic characterization of films were performed by means of UV-Vis and infrared measurements. Photoinduced birefringence measurements of LB mixed films of azopolymer with CdSt were performed as function of time during the buildup of the birefringence and the decay after turning off the excitation light. Experimental results showed that the maximum birefringence achieved during the light excitation increased with the number of layers of the LB film and light intensity. Photoinduced birefringence dynamics was also investigated during the buildup and decay aiming to determine the time constants of bi-exponential functions given by the Sekkat model / Mestre