[pt] Redes de Bragg em fibras ópticas (RBF) são formadas por modulações periódicas introduzidas no índice de refração do núcleo de fibras ópticas. Estes componentes comportam-se como filtros espectrais de banda passante, ou seja, quando iluminados por um sinal óptico de banda larga, refletem apenas uma fina fatia espectral de luz, cujo centro, o comprimento de onda de Bragg, é proporcional ao período espacial da modulação no índice de refração. As RBF têm encontrado aplicações importantes no sensoriamento das mais diversas grandezas, sendo hoje utilizadas em sistemas de monitoramento para vários segmentos industriais, tais como os setores de petróleo e gás, construção civil e aeroespacial, que, estima-se, respondem em conjunto por cerca de 70% destas aplicações. Em diversas situações o sensoriamento com RBF baseia-se em medidas indiretas da grandeza de interesse, sendo empregados mecanismos de transdução que transformam variações do mensurando em deformações na fibra óptica. Nestes casos, um problema que deve ser tratado com atenção é o acoplamento entre temperatura e deformação, uma vez que as RBF são sensíveis a estas duas variáveis. Não raro, a alternativa é utilizar simultaneamente duas RBF para obter-se a compensação de temperatura na medida de deformação. Este trabalho apresenta um estudo sobre deformações não homogêneas em redes de Bragg e discute aplicações de duas técnicas que podem ser utilizadas como alternativas para eliminar o efeito da temperatura no sensoriamento de deformação com apenas uma RBF. A primeira delas explora a birrefringência óptica induzida na RBF por carregamentos transversais à fibra óptica. A segunda baseia-se nos efeitos sobre o espectro refletido pela rede de Bragg quando submetida a um campo de deformações longitudinais não uniformes ao longo da direção axial da fibra óptica. No trabalho são apresentados protótipos e dispositivos que exploram tais técnicas para a medida simultânea de pressão e temperatura. Esses protótipos foram projetados com auxílio de ferramentas CAD e modelados utilizando-se o método de elementos finitos em conjunto com a teoria de modos acoplados da Rede de Bragg. As previsões obtidas utilizando-se estes modelos mostraram-se bastante próximas dos resultados das implementações experimentais dos protótipos, indicando que a metodologia de modelagem desenvolvida pode ser aplicada nos projetos de transdutores baseados nas duas técnicas estudadas. / [en] Fiber Bragg gratings (FBG) are modulations in the effective refractive index of optical fibers, introduced in a small length along the fiber core. Such components operate as narrow band reflective filters, that is, when illuminated by a broad-band light source, they reflect a narrow spectral band centered at a specific wavelength, the Bragg wavelength. This wavelength is proportional to the spatial period of the refractive index modulation. Fiber Bragg gratings have find an increasing number of applications as sensors for different quantities, and today are being employed as part of permanent, real time monitoring systems in various industrial segments. The oil and gas sector, together with civil infrastructure and aeronautics and aerospace, account for almost 70% of this applications. In a number of situations, FBG sensing is based on indirect measurements of the quantity being monitored, and a transduction mechanism is employed to transform changes in the measured quantity in strain sensed by the optical fiber. Since the FBG is sensitive to strain and temperature, proper temperature compensation is always necessary. Usually, a second grating is employed to simultaneously measure temperature and strain, performing the required compensation. This thesis presents a study on effects due to non- homogeneous strains in the Bragg grating and discusses application of two different techniques, based on these effects, to allow temperature compensated strain measurement using a single FBG. The first technique explores strain induced optical birefringence when the fiber is loaded transversely. The second technique is based on changes in the spectral shape of the light signal reflected by the grating when subjected to non homogeneous axial strain fields. Prototypes of pressure and temperature transducers based on these techniques have been developed. These prototypes have been designed by employing CAD techniques and modeled using the finite element method in conjunction with the theory of coupled modes for fiber Bragg gratings. Comparisons between results provided by theoretical models and experimental realizations of the prototypes are very close, demonstrating that the developed approach can be applied to design transducers based on the discussed techniques. Results obtained with the proposed pressure and temperature sensors are also encouraging indicating that the two techniques are suitable for industrial applications.

Made available in DSpace on 2016-04-04T18:31:43Z (GMT). No. of bitstreams: 1 KARYNA SILVEIRA CARDOSO.pdf: 2314345 bytes, checksum: 65e604b78ddbbbc8d0efd8e49a70ac86 (MD5) Previous issue date: 2015-06-16 / This study proposes a strategy to access sensor nodes of a wireless sensor network clumped together in clusters that come together in cells through a hybrid radio topology and / or fiber. In this topology, communication between wireless sensor networks and the repeater is via radio, while the backhaul communication between the base and repeaters will be hybrid and can use radio or fiber. Therefore, the proposal includes a flexible topology, using both radio as fiber in the backhaul and access to sensor nodes via a wireless sensor network. For demonstration of the proposed, tests were done on a channel emulation bench using fiber backhaul between the base and a repeater element. These tests were performed on the 915 MHz band, the FSK varying its transmission rate to assess the coverage area for each rate. As a result curves were obtained showing that for a fixed RSSI, the higher the worse transmission rate is the bit error rate. And the higher the lowest environmental attenuation factor will be the coverage area at all rates tested. Therefore the lower the reception power, the greater the distance between the sensors. Also tests were made in a real environment to evaluate the protocols implemented. It consists in the access of the node sensors of the clusters through multiple hops and reception power measurements of each sensor node and a packet loss rate. Through testing it has verified the operation of the proposal and implemented the flexible topology proposal. / O presente trabalho prop?e uma estrat?gia para acessar n?s sensores de uma rede de sensores sem fio (RSSF) aglutinados em clusters que se unem em c?lulas atrav?s de uma topologia h?brida de r?dio e/ou fibra. Nesta topologia, a comunica??o entre as redes de sensores sem fio e o repetidor ser? via r?dio, enquanto o backhaul de comunica??o entre a base e os repetidores ser? h?brido, podendo utilizar r?dio ou fibra. Portanto, a proposta abrange uma topologia flex?vel, utilizando tanto r?dio quanto fibra no backhaul e acesso aos n?s sensores via uma rede de sensores sem fio. Para demonstrar a proposta foram feitos testes em uma bancada de emula??o de canal utilizando backhaul de fibra entre a base e um elemento repetidor. Estes testes foram realizados na faixa de 915 MHZ, na modula??o FSK variando a sua taxa de transmiss?o, para avaliar a ?rea de cobertura para cada taxa. Como resultados foram obtidas curvas que mostram que para uma RSSI fixa, quanto maior a taxa de transmiss?o pior ser? a taxa de erros de bits (BER). E quanto maior o fator de atenua??o do ambiente menor ser? a ?rea de cobertura da rede em todas as taxas testadas. Logo quanto menor a pot?ncia recep??o, maior a dist?ncia entre os n?s sensores. Tamb?m foram realizados testes em um ambiente real para avaliar os protocolos implementados. Estes testes consistiam no acesso dos n?s sensores dos clusters atrav?s de m?ltiplos saltos e medi??o dos valores de pot?ncia de recep??o de cada n? sensor e sua taxa de perda de pacotes (PER). Atrav?s dos testes realizados foi comprovado o funcionamento da proposta implementada e a topologia flex?vel proposta.

L’accident de Fukushima-Daiichi du 11 Mars 2011 a fortement marqué l'industrie nucléaire en mettant en évidence plusieurs faiblesses dans le contrôle des systèmes critiques qui assurent la sécurité des centrales nucléaires, en particulier, lors de conditions accidentelles. Cette thèse a été réalisée en collaboration avec AREVA, groupe industriel français actif dans le domaine de l'énergie, avec l’objectif de réaliser des capteurs à fibres optiques résistants aux contraintes sévères d'une centrale nucléaire et, en particulier, de surveiller la température et le niveau de l'eau à l'intérieur d’une piscine de stockage de combustible. La thèse est composée de deux parties organisées en 7 chapitres. Dans la première partie, le chapitre 1 traite des phénomènes contribuant à l'atténuation de la lumière au cours de sa propagation dans la fibre et donne un aperçu des effets des radiations sur les fibres optiques. Pour identifier la technique la plus prometteuse adaptée aux applications visées par AREVA, le chapitre 2 propose un état de l’art sur les capteurs distribués à fibres optiques existants avec une attention particulière à leur emploi dans des environnements radiatifs. La dernière partie de ce chapitre est consacrée à la description détaillée de l’OFDR qui est la technique retenue pour cette application. La deuxième partie est consacrée à la présentation des résultats obtenus et leur analyse. Le chapitre 3 présente le détail des irradiations et des traitements thermiques, les échantillons retenus et les bancs de mesure utilisés. Afin de déterminer la meilleure combinaison fibre/technique par rapport à l’application visée, une étude systématique des capteurs distribués de température et de contrainte a été réalisée. Les effets permanents des rayonnements (niveaux de dose du MGy) sont étudiés dans le chapitre 4. Le chapitre 5 illustre des mesures in situ sur les fibres résistantes aux radiations pour comprendre les effets combinés de la température et des radiations (rayons X), effets représentatifs des conditions nominales et accidentelles des piscines de stockage. Enfin, nous avons développé un prototype de capteur de niveau d’eau pour les piscines de combustible qui est décrit dans le chapitre 6. Ensuite, les principales conclusions et les perspectives de ce travail de thèse sont discutées / Fukushima-Daiichi event on March 11th, 2011, signed a turning point in nuclear industry by highlighting several weaknesses in the control of critical systems that ensure the safety in nuclear power plant (NPP) operating, particularly, in accidentals conditions. This PhD thesis has been carried out in collaboration with AREVA, the French industrial group active in the energy domain, with the aim of realizing optical fiber sensors resistant to the harsh environment constraints of a NPP and, in particular, to monitor temperature and water level several parameters inside the spent fuel pools (SFPs). It consists of two parts organized in 7 chapters. In the first part, chapter 1 deals with the phenomena contributing to the light attenuation during its propagation along the fiber and gives an overview on the radiation effects on optical fibers. To identify the most promising technique suitable for AREVA needs, in chapter 2 is reported the state-of-the-art on the distributed OFSs with particular attention to their employment in radiation environments. The last part of this chapter is devoted to the detailed description of the OFDR that is the selected sensor technique for this application. The second part is devoted to present and discuss the obtained results. Chapter 3 gives the experimental details on radiation and thermal treatments, investigated samples and used setups. In order to determine the best fiber/setup combination, a systematic study on temperature and strain distributed sensors was carried out in relation to the harsh constraints demanded from the application. The permanent radiation (MGy dose levels) effects on different fiber classes are investigated in Chapter 4. Chapter 5 illustrates in situ measurements on radiation resistant fibers to understand the combined temperature and radiation (X-rays) effects representative of the SFP nominal and accidental conditions. Simultaneously, we have developed the OFS design for its integration at SFP facility. The prototype is described and its performance is evaluated in chapter 6. Then, the main conclusion and perspective are discussed / L'incidente di Fukushima-Daiichi dell’11 marzo 2011 ha segnato un punto di svolta per l’industria nucleare, mettendo in evidenza diversi punti deboli nel controllo di sistemi critici che garantiscono la sicurezza nelle centrali, in particolare in condizioni di incidente. Questa tesi è stata condotta in collaborazione con AREVA, il gruppo industriale francese attivo nel settore dell'energia, con l'obiettivo di produrre sensori a fibra ottica resistenti alle condizioni estreme di una centrale nucleare e, in particolare, per controllare diversi parametri all'interno di una piscina di stoccaggio di combustibile nucleare, quali la temperatura e il livello dell'acqua. La tesi si compone di due parti organizzate in 7 capitoli. Nella prima parte, il capitolo 1 riguarda i fenomeni che contribuiscono all'attenuazione della luce durante la sua propagazione nella fibra e permette di comprendere gli effetti della radiazione sulle fibre ottiche. Per identificare la tecnologia più promettente per le esigenze di AREVA, nel capitolo 2 é discusso lo stato dell’arte sui sensori distribuiti con particolare attenzione alle loro performance in ambienti radiativi. L'ultima parte di questo capitolo è dedicato ad una descrizione dettagliata della tecnica OFDR che è la tecnologia scelta per questa applicazione. La seconda parte è dedicata a presentare e discutere i risultati. Il capitolo 3 fornisce i dettagli sui campioni studiati e i trattamenti effettuati su di essi e descrive il setup utilizzato. Per determinare la migliore combinazione fibra/tecnica per l’applicazione prevista, è stato eseguito uno studio sistematico sulla risposta alla radiazione dei sensori distribuiti di temperatura e strain. Glieffetti permanenti della radiazione (dosi dell’ordine del MGy) su diverse classi di fibre, resistenti e sensibili alle radiazioni, sono discussi nel capitolo 4. Il capitolo 5 riporta le misure in situ sulle fibre resistenti alla radiazione per investigare gli effetti combinati di temperatura e radiazioni (raggi X) rappresentativi delle condizioni operative e accidentali nelle piscine di stoccaggio. Infine, abbiamo sviluppato un prototipo di sensore del livello dell’acqua nelle piscine di stoccaggio che è descritto nel capitolo 6. In seguito, le principali conclusioni e le prospettive sono discusse

Les interféromètres stellaires sont des dispositifs à très haute résolution angulaire, permettant une étude approfondie de l’Univers. Cette thèse décrit la mise en place en laboratoire d’un interféromètre à somme de fréquences dédié à la détection de rayonnement infrarouge en bande L :ALOHA@3.39. Afin de pouvoir limiter le bruit généré par les rayonnements thermiques ambiants et de pouvoir bénéficier des technologies matures en terme de détection et de transport cohérents de la lumière collectée, ce système intègre sur chacune des voies interférométrique un processus non linéaire de somme de fréquence. Les rayonnements autour de 3.39 μm sont transposés autour de 810 nm via des cristaux de PPLN alimentés par une pompe unique à 1064 nm. Une première partie présente le contexte expérimental et théorique de la thèse. La deuxième partie concerne la conception, la réalisation et la caractérisation du banc ALOHA@3.39. La troisième partie présente les résultats expérimentaux obtenus en laboratoire. La mesure répétée du contraste en régime de fort flux permet de calibrer le contraste instrumental du montage. Les premières mesures en régime de comptage de photons montrent que nous sommes actuellement capables de détecter des franges d’interférence avec de hauts contrastes en ne disposant que de 100 Fw à l’entrée de chacune des voies. Enfin, nos investigations nous ont amené à la détection de franges d’interférences via le prototype ALOHA@3.39 à partir d’une source thermique, assimilable à un corps noir. Cette thèse conclue sur une estimation de la magnitude limite accessible, et sur l’utilisation de nouvelles technologies de PPLN. / Stellar interferometers are high angular resolution devices, allowing for detailed research of the Universe. This thesis describes the in-lab implementation of a sum frequency generation interferometer dedicated to the infrared detection in the L band : ALOHA@3.39. In the aim of limiting thermal noise due to the room radiation, and benefit mature detectors and fibered components, this device includes a sum frequency generation non-linear process on each of its arms. Stellar radiations around 3.39 μm are transposed to around 810 nm thanks to PPLN cristals powered by a single pump signal at 1064 nm. The first part presents our global experimental context and theoretical elements about this thesis. The second part deals with the conception, the implementation and characterisation of the test bench ALOHA@3.39. The third part tables in-lab experimental results. Repeated measurements of the fringe contrast on high flux regime allow to calibrate the instrumental contrast of the set-up. First measurements on photon counting regime show we are currently able to detect interference fringes with high contrast with only 100 fW at the input of each arm. Finally, our research led us to realise interference fringes detection via the ALOHA@3.39 prototype, observing a thermal source, considered as a black body. This thesis concludes on an estimation of the limiting reachable magnitude, and on the future use of new PPLN technologies.

La structuration et la fonctionnalisation de réseaux de fibres optiques ont été utilisées afin de réaliser différents capteurs électrochimiques et luminescents. Ce type de support permet de concevoir des capteurs capables de détecter à distance dans un milieu confiné, difficilement accessible ou dangereux. Deux capteurs pour la détection du mercure cationique (Hg2+) sont décrits dans cette thèse. Le premier utilise un dérivé de la rhodamine, qui est lié de façon covalente à la surface en verre du réseau, par silanisation. Le signal fluorescent de cette sonde est augmenté en présence de mercure ce qui permet de le quantifier. Le second capteur combine l’électrochimie sur ces réseaux de fibres optiques, grâce à une fine couche conductrice déposée à sa surface. Le réseau est ensuite modifié avec un complexe de Ruthénium(II), qui peut être électropolymérisé par l’intermédiaire de la fonction cyclopentadithiophène (CPDT). La détection du mercure est alors réalisée par électrochimiluminescence (ECL), qui est collectée à distance, grâce aux propriétés électro-modulables du film polymère. Les réseaux de fibres optiques nanostructurés ont également été utilisés pour la réalisation d’une sonde SECM, présentant un réseau dense de nanoélectrodes collectives. La réalisation d’un tel outil utilise le positionnement basé sur les forces de cisaillement et peut être utilisé pour la structuration de surfaces conductrices ou isolantes par SECM. / The structuration and the functionalisation of optical fiber bundles have been used to design different optical and electrochemical sensors. The use of these tools allows the realisation of sensors for remote detection in a confined environment, which may be dangerous or not easily accessible. Two sensors for the detection of inorganic mercury (Hg2+) are described in this thesis. The first sensor uses a rhodamine derivative, which is covalently functionalized on the surface of the glass optical fibers by silanisation. The fluorescent signal of this probe increases in presence of mercury, which allows its quantification. The second sensor uses the combination of electrochemistry on the optical fiber bundle, thanks to a thin conductive layer deposited on its surface. The bundle is then modified by electropolymerisation of a Ruthenium (II) complex through the cyclopentadithiophene (CPDT) moiety. The detection of mercury is then realised by elecrogenerated chemiluminescence (ECL), which is collected through the optical fiber bundle, thanks to the optical properties of the polymer film. The nanostructured array of optical fibers has also been used to create a new SECM probe composed of a dense nanoelectrode array. Such a tool is obtained through Shearforce positioning and can be used for the structuration of conductive or insulating surfaces by SECM.

Formatos de modulação com capacidade de ajuste às condições variáveis de propagação são de interesse para uso em redes ópticas reconfiguráveis. Alterações nos níveis de potência e no mapa de dispersão afetam o desempenho de sistemas de transmissão, limitando o alcance e a capacidade de reconfiguração da rede. Fornecer capacidade de ajuste dinâmico ao sinal transmitido, sem usar sistemas complexos de modulação ou de compensação variável de dispersão, é uma solução eficaz para se obter rendimento ótimo nas diversas condições de propagação na rede. Esta característica também é útil na instalação de redes convencionais, poupando tempo e reduzindo custos. Neste trabalho é proposto o formato de modulação NRZ com gorjeio sincronizado com o sinal como alternativa para sobrepujar as limitações impostas pelas redes reconfiguráveis. O sistema proposto tem o atrativo de permitir, além da capacidade de adaptação, a possibilidade de integração dos componentes ópticos do modulador num mesmo substrato. O desempenho do formato de modulação proposto foi analisado em diversas condições de propagação para sistemas a 10 Gbit/s, tanto em sistemas ponto-a-ponto como de longas distâncias. Esta análise foi feita por meio de modelagem matemática, simulações numéricas e experimentos em laboratório. Foi demonstrada a capacidade de ajuste a diversos mapas de dispersão e seus limites, bem como a compensação de efeitos da automodulação de fase causados por alterações no nível da potência do sinal. / Modulation formats with adjustment capability to the variable propagation conditions are of interest in reconfigurable optical networks. Changes in optical power levels and dispersion compensation map affect the transmission system performance, limiting the range and the network reconfiguration capability. To provide dynamical adjustment capability to the transmitted signal, using neither complex modulation systems nor variable dispersion compensation, is an effective solution to obtain optimal performance within the diverse network propagation conditions. This characteristic is also useful during conventional networks installation, saving time and reducing costs. In this work it is proposed the NRZ modulation format with signal synchronized chirp as an alternative to overcome the limitations imposed by the reconfigurable networks. The proposed system has the benefit of allowing, more than adaptation capability, the possibility of integration of the optical modulator\'s components in the same substrate. The proposed modulation format was analyzed under diverse propagation conditions for 10 Gbit/s, in point-to-point as well as long-haul systems. This analyses war performed by mathematical modeling, numerical simulations and laboratorial experiments. It was demonstrated the adjustment capability for diverse dispersion compensation maps and its limits as well as the compensation of the self-phase modulation effects due to changes in optical power levels.

[pt] O setor de petróleo e gás apresenta diversas oportunidades de aplicação para os sensores a fibra óptica. Algumas características inerentes às fibras ópticas, como baixo peso, flexibilidade, longa distância de transmissão, baixa reatividade do material, isolamento elétrico, imunidade eletromagnética e alta capacidade de multiplexação, podem ser determinantes em diversas situações, seja nos segmentos de exploração, transporte, refino ou distribuição. As principais operadoras internacionais do setor identificaram a tecnologia de Sensores a Fibra Óptica como elemento chave para viabilizar, com toda a funcionalidade esperada, a instalação de sistemas de completação inteligente de poços de petróleo (produção ou injeção). O sensoriamento do poço permite obter, a qualquer momento, informações precisas sobre diversas grandezas, entre outras a pressão, temperatura, vazão, pH ou mesmo a posição de válvulas que controlam o fluxo através do poço. A monitoração em tempo real do poço é parte da estratégia de automação do processo de produção do campo de petróleo. Esta é uma tendência que no futuro próximo aponta para a exploração de campos de petróleo inteligentes, onde a produção por vários poços de um mesmo reservatório realizase de forma otimizada e automatizada, reduzindo custos, e aumentando fatores de recuperação das reservas de hidrocarbonetos fósseis. O presente trabalho se insere neste contexto, e apresenta a concepção, desenvolvimento e resultados de testes de dois protótipos de transdutores de fundo do poço para integrar um sistema de completação inteligente baseado na tecnologia de sensoriamento utilizando redes de Bragg em fibras ópticas. O primeiro deles destina-se à medida da pressão diferencial num sensor de vazão do tipo Venturi. Resultados de testes com protótipos do transdutor demonstraram que ele pode operar numa faixa de mais ou menos 5 bar de pressão diferencial, sob pressões médias de até 21 MPa e temperaturas de 90 graus Celsius com resolução de 0,06 por cento do fundo de escala. O segundo transdutor desenvolvido, aplica-se à medida da posição de abertura e fechamento de uma válvula controladora de fluxo tipo camisa deslizante (sliding sleeves). Duas técnicas foram investigadas. A primeira delas, para aplicações mais gerais, baseia-se no uso de atuadores magnetoestrictivos. A segunda procurou atender a um projeto específico para este tipo de válvula, em cuja concepção utiliza-se uma mola elástica para exercer a força de restituição contra um atuador hidráulico. Neste caso, optou-se por desenvolver uma célula de carga instrumentada com redes de Bragg. Nos testes realizados foram obtidos resultados satisfatórios em termos de sensibilidade e resolução, tendo-se chegado para esta última a valores próximos de 0,03 mm num curso de 70 mm (0,04 por cento do fundo de escala). / [en] Optical fibers are finding a growing range of new applications in the petroleum industry, which include, not only those already well established in telecommunications, but also in novel sensing technologies. Possibility of dense multiplexing, continuous distributed measurements, long distances between measurement points and electronic circuits, and explosion risk free, are some of the characteristics shared by different types of optical fiber sensors. The major global oil and gas operators and service companies have elected optical fiber sensing as one of the key enablers to implement with all the expected functionality and reliability the novel technology of intelligent well completion. Continuous well monitoring allows the operator to access, at any time during the well life, important information regarding different process variables, such as pressure, temperature, flow-rate, pH, or even the position of sliding sleeves valves that control the flow through the well. This is part of the automation strategy to optimize production in the whole reservoir, a technological trend that points towards the concept of an intelligent oil field and that, in the near future, will be applied to the integrated management of production from several wells in the same reservoir, contributing to reduce intervention costs, and increasing recovery factors of fossil hydro-carbon reserves. The present work is inserted in this context, and reports the conception, development and results of tests conducted with prototypes of two different optical fiber transducers to be integrated in an intelligent well completion system. The first one is a Bragg grating differential pressure transducer, which has been developed to measure pressure drop across a Venturi flow-meter inserted in the production tubing. Test results with prototypes have demonstrated that the transducer may be applied to measure differential pressures in the range of more or less 5 bar, under static (average) pressures up to 21 MPa and temperatures below 90 Celsius Degree, with 0.06 percent full-scale resolution. The second development is a displacement transducer applied to measure the opening position of sliding sleeves valves. Two different measurement principles were investigated. The first, intended to general applications of displacement measurements, relied on the use of magnetostrictive actuators and fiber Bragg grating sensors. The second displacement transducer applies to a specific type of valve, which employs a mechanical spring to provide recovery forces to a hydraulic actuator. The proposed solution was based on the use of a load cell instrumented with fiber Bragg gratings. Tests results demonstrated that the prototype transducer was capable of resolving changes in displacement as lower as 0.03 mm in a full-range of 70 mm, approximately 0.04 percent full-scale resolution.

Ce mémoire présente la modélisation, la simulation, l’expérimentation et la conception d’une structure composite intelligente pour des mesures de haute température (jusqu’à 300 °C). Pour ce faire, une fibre à revêtement métallique, particulièrement résistante pour de tels niveaux thermiques, a été considérée et intégrée au sein d’un revêtement d'alumine. La structure composite intelligente se compose alors du substrat, du dépôt et d’un capteur à fibre optique à modulation d’intensité. Pour mener cette étude, une estimation des flux thermiques basée sur le thermogramme expérimental s’est révélée nécessaire afin d’alimenter un modèle numérique. Différents modèles ont ensuite été construits afin d’évaluer les niveaux de températures atteints en surface ainsi que les niveaux de contraintes au sein même du composite. La simulation a montré que le dépôt pouvait thermiquement être considéré comme une couche mince et que la diffusion de la chaleur au sein du dépôt et du substrat était rapide et pouvait être estimée à l'échelle de la milliseconde. La répartition des contraintes est comme on pouvait s'y attendre dépendante du flux incident mais aussi de la géométrie globale du composite. Les contraintes restent relativement uniformes lors de l'échauffement et durant leur propagation mais s’intensifient après le refroidissement. Il s'avère également que les contraintes résultantes ne sont pas symétriques dans la fibre et sont dépendantes de la position de la fibre par rapport au substrat. Après une phase de modélisation des niveaux thermiques et des contraintes susceptibles d’être atteints au sein du matériau, une phase expérimentale consistant à intégrer une fibre optique non fonctionnalisée dans un dépôt d’alumine a donc été réalisée. Les observations microscopiques en surface et en coupe ont été effectuées afin de vérifier l’intégrité de la fibre intégrée. L’adhérence mécanique des fibres a ensuite été mesurée ainsi que l’atténuation optique pendant le processus d’intégration et le comportement thermique de l’ensemble durant des cyclages thermiques. Enfin, un capteur à fibre optique à modulation d’intensité a été conçu par intégration dans un dépôt céramique réalisé par projection thermique. Un système de mesure de la température a donc été construit et les premiers essais de réponse thermique ainsi que le cyclage thermique du capteur de température ont été effectués et analysés. En concluision, cette étude démontre la faisabilité d’une structure composite intelligente par intégration d'un capteur à modulation d’intensité à fibre optique dans un dépôt céramique élaboré par projection thermique susceptible de pouvoir travailler jusqu’à des températures de 300 °C. / This paper presents the modeling, simulation, experimentation and design of a smart composite structrure for high temperature measurements (up to 300 °C). In order to achieve this goal, a high temperature resistant metal coated optical fiber was considered and integrated into alumina coating. The smart composite structure consists of a substrate, a coating and an intensity modulated optical fiber temperature sensor. Firstly, an estimation of heat flux based on a experimental thermogram was firstly carried out in order to feed a numerical modeling. Then, different modelings were built to evaluate the surface temperature levels as well as the composite stress levels. The simulation showed that the composite (substrate and coating) could be considered as a thermally thin medium, the heat propagation within the composite was fast and could be estimated at a scale of millisecond. The stresses remained relatively uniform during the heating process but intensified during the cooling process. The modeling also showed that the stresses are not symmetrical in the fiber and depend on the position of the fiber relative to the substrate. After a modeling evaluation of the thermal levels as well as the stresses that may be achieved in the composite, an experimental step integrating a optical fiber into a thermal coating was carried out. Microscopic observation of surface and cross section were conducted in order to analyze the characteristics of the integrated fiber. The mechanical strength of the integrated fiber was then measured and the optical attenuation during the integration process as well as the thermal behavior of the integrated fiber during the thermal cycling were evaluated. Finally, an intensity modulated optical fiber temperature sensor was designed and integrated into ceramic coating by thermal spraying. A temperature measuring system was designed and the first tests of the thermal response as well as thermal cycling of temperature sensor were carried out. This study demonstrates the feasibility of designing a high temperature resistant smart composite structure by integrating an intensity modulated optical fiber temperature sensor in a ceramic coating elaborated by thermal spraying.

This thesis describes the development of a combined label-free imaging and analytical strategy for intraoperative characterization of cancer lesions using the coherent anti-Stokes Raman scattering imaging (CARS) technique. A cell morphology-based analytical platform is developed to characterize CARS images and, hence, provide diagnostic information using disease-related pathology features. This strategy is validated for three different applications, including margin detection for radical prostatectomy, differential diagnosis of lung cancer, as well as detection and differentiation of breast cancer subtypes for in situ analysis of margin status during lumpectomy. As the major contribution of this thesis, the developed analytical strategy shows high accuracy and specificity for all three diseases and thus has introduced the CARS imaging technique into the field of human cancer diagnosis, which holds substantial potential for clinical translations. In addition, I have contributed a project aimed at miniaturizing the CARS imaging device into a microendoscope setup through a fiber-delivery strategy. A four-wave-mixing (FWM) background signal, which is caused by simultaneous delivery of the two CARS-generating excitation laser beams, is initially identified. A polarization-based strategy is then introduced and tested for suppression of this FWM noise. The approach shows effective suppression of the FWM signal, both on microscopic and prototype endoscopic setups, indicating the potential of developing a novel microendoscope with a compatible size for clinical use. These positive results show promise for the development of an all-fiber-based, label-free imaging and analytical platform for minimally invasive detection and diagnosis of cancers during surgery or surgical-biopsy, thus improving surgical outcomes and reducing patients' suffering.

The terms &lsquo / ground-probing radar&rsquo / , &lsquo / ground penetrating radar (GPR)&rsquo / , &lsquo / sub-surface radar&rsquo / or &lsquo / surface-penetrating radar (SPR)&rsquo / refer to various techniques for detecting and imaging of subsurface objects. Among those terms GPR is preferred and used more often. In this thesis, the depth and the position of the buried circular cylinder are determined by a GPR system which comprises of an optical fiber sensor (OFS). The system is a combination of OFS, GPR and optical communication link. In order to determine the depth and the position, first of all the electric field distribution at the OFS is obtained by integrating the Green&rsquo / s function over the induced current distribution. Those distributions are observed for different frequency and depth values. The voltages inside the distribution are measured by OFS. By changing the depth of the cylinder and the frequency of the system, various plots showing x axis displacement versus measured voltages are obtained. Those plots are related to interference fringe patterns. The position and the depth of the cylinder are obtained using interference fringe patterns. All of the studies mentioned are performed in MATLAB R2007b program. The noises of the system due to OFS are extracted using OPTIWAVE OPTISYSTEM 7.0 program. By adding those noises to the measured voltage values, the operating frequency of the system is observed.