Physical and functional properties of advanced nano-composite materials and biological structures are determined by self-organized atoms and molecules into nanostructures and in turn by microscopic organization of the nanostructures into assemblies of higher structural complexity. Therefore, microscopes are indispensable tools for structural investigations at various levels of organization. In this work, novel nonlinear optical microscopy methods were developed to non-invasively study structural organization at the nanoscopic and microscopic levels. Atomic organization of semiconductor nanowires, molecular organization of amylose biocrystallites in starch granules, and microscopic organization of several photosynthetic organisms was elucidated. The structure of ZnSe nanowires, key components in many modern nanodevices, was investigated using polarization harmonic generation microscopy. Based on nonlinear optical properties of the different crystal lattices, zinc blende and wurtzite nanowires were differentiated, and the three-dimensional orientation of the zinc blende nanowires could be found. The structure of starch granules, a model biocrystal, important in food as well as health sciences, was also investigated using polarization harmonic microscopy. The study was combined with ab initio calculations using the crystal structures of amylose A and B, revealing that second harmonic signals originate from the hydroxide and hydrogen bonds in the starch granules. Visualization of several photosynthetic organisms including the green algae, Chlamydomonas reinhardtii, two species of cyanobacteria, Leptolyngbya sp. and Anabaena sp., aggregates of light-harvesting pigment-protein complexes as well as chloroplasts from green plants were also explored, revealing that future nonlinear microscopy applications could include structural studies of cell walls, the Chlamydomonas eyespot, and photosynthetic membranes. In this study, several nonlinear optical microscopy modalities were developed for quantitative structural investigations of nano and micro-sized architectures. Non-invasive extraction of crystallographic information in microscopic samples will have a number of potential benefits, for example, in clinical applications, allowing observations of disease states inside tissues without the need for biopsy. Industrial nanotechnology will benefit from fast determination of nanostructures with nonlinear microscopy that will improve quality of nanodevices.

Physical and functional properties of advanced nano-composite materials and biological structures are determined by self-organized atoms and molecules into nanostructures and in turn by microscopic organization of the nanostructures into assemblies of higher structural complexity. Therefore, microscopes are indispensable tools for structural investigations at various levels of organization. In this work, novel nonlinear optical microscopy methods were developed to non-invasively study structural organization at the nanoscopic and microscopic levels. Atomic organization of semiconductor nanowires, molecular organization of amylose biocrystallites in starch granules, and microscopic organization of several photosynthetic organisms was elucidated. The structure of ZnSe nanowires, key components in many modern nanodevices, was investigated using polarization harmonic generation microscopy. Based on nonlinear optical properties of the different crystal lattices, zinc blende and wurtzite nanowires were differentiated, and the three-dimensional orientation of the zinc blende nanowires could be found. The structure of starch granules, a model biocrystal, important in food as well as health sciences, was also investigated using polarization harmonic microscopy. The study was combined with ab initio calculations using the crystal structures of amylose A and B, revealing that second harmonic signals originate from the hydroxide and hydrogen bonds in the starch granules. Visualization of several photosynthetic organisms including the green algae, Chlamydomonas reinhardtii, two species of cyanobacteria, Leptolyngbya sp. and Anabaena sp., aggregates of light-harvesting pigment-protein complexes as well as chloroplasts from green plants were also explored, revealing that future nonlinear microscopy applications could include structural studies of cell walls, the Chlamydomonas eyespot, and photosynthetic membranes. In this study, several nonlinear optical microscopy modalities were developed for quantitative structural investigations of nano and micro-sized architectures. Non-invasive extraction of crystallographic information in microscopic samples will have a number of potential benefits, for example, in clinical applications, allowing observations of disease states inside tissues without the need for biopsy. Industrial nanotechnology will benefit from fast determination of nanostructures with nonlinear microscopy that will improve quality of nanodevices.

Neste trabalho fizemos um estudo da geração de terceiro harmônico (GTH) usando pulsos de femtossegundos (fs). A GTH é uma importante técnica que permite estudar propriedades ópticas não lineares de terceira ordem de materiais. Estudamos a GTH aplicando as técnicas de franjas de Maker e a de varredura-Z em diferentes materiais levando em conta as contribuições de suas interfaces. A técnica de franjas de Maker com GTH permite a determinação de propriedades ópticas lineares e não lineares de volume, mas não de interface, portanto, a técnica de varredura-Z na condição de focalização forte foi implementada para estudar a influência da interface na GTH. Estudamos diversos vidros ópticos (sílica, K10, SK11, LLF1 e LLF6) e também diferentes soluções (acetona, clorofórmio, DMSO e tolueno) em uma cubeta. Em termos de número de interfaces, usando uma lâmina de vidro temos duas, no caso de um sanduíche de dois vidros temos três (entrada, meio e saída) e temos quatro interfaces para a cubeta. Observamos que elas contribuem tanto nas intensidades quanto nos espectros dos terceiros harmônicos (TH) gerados. Dependendo do tipo de interface e do sentido de propagação, tanto a intensidade quanto o espectro do TH são diferentes. Observamos que a reflexão de Fresnel atua significativamente nas diferenças de intensidades da GTH nas interfaces entre dois meios com índices de refração lineares diferentes. Uma interferência construtiva ocorre quando o feixe de laser propaga de um material com índice de refração mais alto para outro com índice mais baixo, aumentando a intensidade do laser e, consequentemente, gerando mais TH. Uma interferência destrutiva ocorre numa propagação oposta. Outro efeito interessante observado foi que, além da magnitude da não linearidade do meio, existem as contribuições da propagação e da modulação de fase cruzada no alargamento espectral do TH. Dessa forma, o alargamento espectral depende da não linearidade do meio e também do sentido de propagação no caso de interfaces. Em resumo, esse estudo nos levou a uma melhor compreensão dos fenômenos não lineares de GTH nas interfaces, e também possibilitou o surgimento de um novo método que pode ser usado para a determinação da susceptibilidade de terceira ordem de materiais. / In this work we did a study of the third-harmonic generation (THG) using femtosecond pulses. The THG is an important technique which allows studying thirdorder nonlinear optical properties of materials. We studied the THG by the Maker fringes and the Z-scan techniques in different materials taking into account their interfaces contributions. The Maker fringes technique with THG allows the determination of the bulk linear and the nonlinear properties, but not of the interface. Therefore, the Z-scan technique in the tight focused condition was implemented to study the interface influences on the THG. We studied several optical glasses (silica, K10, SK11, LLF1 and LLF6) and different solutions (acetone, chloroform, DMSO and toluene) in a cuvette. In term of numbers of interfaces, using a glass slab we have two, in the case of two sandwiched optical glasses we have three (input, middle and output) and for the cuvette we have four interfaces. We have observed that they play an important role on the third-harmonic (TH) intensities and spectra. Depending of the interface type and propagation direction, the TH intensity and spectrum are different. We have observed that the Fresnel reflection has a significant effect on the THG intensity differences between two media with different linear refractive indices. A constructive interference occurs when the laser beam propagates from one material with higher refractive index to one with lower refractive index, increasing the laser intensity and, consequently generating more TH. A destructive interference occurs in the opposite propagation case. Another important effect observed was that, beside the materials nonlinearity magnitude, there are propagation and cross-phase modulation contributions to the TH spectrum broadening. In this way, the spectrum broadening depends on the materials nonlinear properties and the propagation direction on the case of interfaces. In summary, this study leads to a better understanding of the TH nonlinear phenomena, and also, has allowed one new method for third-order nonlinear susceptibility determination.

Third-harmonic generation (THG) is a fundamental nonlinear optical process that has been used in different applications such as third-order nonlinear materials characterization and nonlinear microscopy. It is widely employed since the third-order nonlinearity is the most important in isotropic materials and THG occurs in all media regardless of symmetry. In the tightly focused laser beam condition THG is observed only at the materials interfaces, where the focal symmetry is broken due to the presence of two media with different refractive index and/or third-order susceptibilities. Measuring slabs of different types of optical glasses, using femtosecond laser pulses, we could explain the asymmetric THG intensity profile observed at the interfaces. The harmonic generated at the exit interface is systematically stronger than the one generated at the entrance and this phenomenon can be understood by taking into account the presence of self-focusing effects. Basically, the self-focusing reduces the beam waist radius at the exit interface, resulting in greater laser irradiance and, consequently, higher THG. This study was then extended to the interfaces of a cuvette filled with organic solvents. Such systems present four interfaces and a mixture of nonlinear processes contributions since the cuvette walls present only electronic nonlinearity and the solvents present both electronic and orientational ones. In this way, the solvents may present an additional self-focusing contribution and, due to the noninstantaneous nature of the orientational process, the self-focusing from the solvent may be influenced by the pulse duration. In this case, the THG, which is an instantaneous electronic phenomenon, can be indirectly affected by pulse duration by means of the self-focusing effect. Usually, the slow orientational contribution is not considered for materials characterization by THG which may lead to incorrect nonlinear coefficient values, that means our study is important from the fundamental physics point of view and also for applications such as materials characterization. Based on the application of THG in nonlinear microscopy, we also present a microscopy technique which makes use of spatial frequency-modulated imaging (SPIFI) with single element detection. The microscope was developed at Colorado School of Mines (CSM) during an internship. The system uses a spatial light modulator (SLM) to provide the spatial frequency modulation and permits enhanced resolution images. THG SPIFI images are shown for the first time and we also report images obtained by other nonlinear optical process. In summary, the studies presented in this PhD work are of great importance for THG fundamental understanding, materials characterization and nonlinear optical microscopy. / Geração de terceiro harmônico (GTH) é um processo óptico não linear fundamental que tem sido usado em diferentes aplicações, como em caracterização óptica não linear de materiais e microscopia não linear. Ele é amplamente empregado uma vez que a não linearidade de terceira ordem é a mais importante em materiais isotrópicos e GTH ocorre em todos os meios independente da simetria. Na condição de feixe fortemente focalizado a GTH é observada apenas nas interfaces do material, onde a simetria focal é quebrada devido à presença de dois meios com diferentes índices de refração e/ou susceptibilidades de terceira ordem. Medindo lâminas de diferentes tipos de vidros ópticos, com pulsos de laser de femtossegundos, nós explicamos o perfil assimétrico de intensidade de GTH observado nas interfaces. O harmônico gerado na interface de saída é sistematicamente mais intenso do que o gerado na entrada e este fenômeno pode ser entendido levando-se em conta a presença do efeito de autofocalização. Basicamente, a autofocalização reduz a cintura do feixe na interface de saída do material, resultando em uma maior irradiância e, consequentemente, maior GTH. Este estudo foi estendido para o caso de interfaces de uma cubeta preenchida com diferentes solventes orgânicos. Tais sistemas apresentam quatro interfaces e uma mistura na contribuição dos processos não lineares, dado que as paredes da cubeta apresentam apenas não linearidade eletrônica e os solventes podem apresentar não linearidades tanto eletrônicas quanto orientacionais. Neste sentido, os solventes podem apresentar uma contribuição adicional de autofocalização e, devido à natureza não instantânea do processo orientacional, a autofocalização proveniente do solvente pode ser influenciada pela duração do pulso. Neste caso, a GTH, que é um fenômeno eletrônico (instantâneo), pode ser indiretamente afetada pela duração do pulso por meio do efeito de autofocalização. Usualmente, a contribuição orientacional não é considerada na caracterização de materiais por GTH, o que pode levar à valores incorretos para os coeficientes não lineares, o que significa que nosso estudo é importante do ponto de vista de física fundamental como também em aplicações como caracterização de materiais. Por conta da aplicação da GTH em microscopia não linear, apresentamos também nesta tese uma técnica de microscopia, que baseia-se em uma modulação em frequência espacial para imageamento (SPIFI) com uso de um detector de elemento único. O microscópio foi desenvolvido na Colorado School of Mines (CSM) durante um período de estágio. O sistema utiliza um modulador espacial de luz (SLM) para produzir a modulação em frequência espacial e permite obtenção de imagens em alta resolução. Imagens por GTH SPIFI são mostradas pela primeira vez e também apresentamos imagens obtidas por outros processos ópticos não lineares. Em resumo, os estudos apresentados neste trabalho de doutorado são de grande importância para o entendimento fundamental do processo de GTH, caracterização de materiais e microscopia óptica não linear.

Orientador: Carlos Lenz Cesar / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-17T16:12:03Z (GMT). No. of bitstreams: 1 Pelegati_VitorBianchin_M.pdf: 3778666 bytes, checksum: d19d947cc4b4206345d5c2da244362d6 (MD5) Previous issue date: 2010 / Resumo: Biologia celular é um novo mundo promissor com enorme impacto social, econômico e na saúde. Organismos vivos são capazes de, produzir a própria energia a partir da luz do sol, se reproduzir, de se auto-reparar, sinalizar e navegar por sinais bioquímicos, biomecânicos, luminosos, térmicos, e outros, e produzir materiais à temperatura ambiente. As possibilidades abertas por essa área incluem, desde bactérias e protozoários usados para destruir células de câncer, regeneração de órgãos inteiros, produção de etanol a partir de algas, e outros. Entretanto, para o entendimento da biologia em seu nível mais profundo, ferramentas de observação não destrutivas fazem-se necessária para seguir os processos celulares durante seu tempo de vida. A óptica tem a única onda não destrutiva capaz de fornecer informações em tempo real com suficiente resolução espacial de eventos acontecendo internamente à célula. Ademais, porque feixes de luz não colidem, a óptica permite a integração de diferentes técnicas capazes de reunir informações simultâneas de processos celulares. Óptica não linear é especialmente adequada para tal, pois não requer marcação ou processamentos especiais de amostras que poderiam destruir, ou modificar, os processos celulares. Além disso, técnicas elásticas, como a geração de segundo e terceiro harmônicos não liberam energia no material que é, portanto, preservado após a observação. O objetivo dessa tese é desenvolver uma plataforma multimodal para observação de processos biológicos pelo uso de microscopias de fluorescência excitada por absorção de dois fótons, geração de segundo harmônico e geração de terceiro harmônico no mesmo instrumento. Nosso grupo foi pioneiro em demonstrar a aquisição de imagens de geração de segundo harmônico no Brasil e, essa tese é a primeira a realizar a aquisição de imagens por geração de terceiro harmônico. Estas três técnicas juntas fornecem informações complementares a respeito da organização de células e tecidos. Enquanto a fluorescência pode ser específica para algumas proteínas alvo, o segundo harmônico pode observar a rede de colágeno da matriz extra celular e, o terceiro harmônico pode observar os núcleos e gotículas de lipídios internas às células. Esta tese descreve o sistema experimental para realizar essas aquisições multimodais de imagens, a física por trás dos sinais não lineares, importantes para entender seu significado biológico, e mostra aplicações das técnicas para diferentes amostras biológicas e inorgânicas / Abstract: Cell biology is promising a brave new world with enormous social economic and health impacts. Living organisms are capable of producing their own energy from sun light, reproduce, self-repair, signalize and travel in response to biochemical, biomechanical, light and thermal signals among others, and to produce materials at room temperature. The possibilities opened by this area range from bacteria and protozoa used to destroy cancer cells, whole organs regeneration, ethanol produced from algae, and others. However, to actually understand biology at its deepest level no destructive observation tools are necessary to follow cell processes during their time course. Optics is about the only wave capable to provide non destructive real time information with enough spatial resolution of the events happening inside the cells. Moreover, because light beams do not collide, optics allows the integration of different techniques capable to gather simultaneous information during a cell process. Non linear optics is specially suited for that in the sense that it does not require staining or special sample processing that would destroy, or change, the process. Besides, elastic techniques such as second and third harmonic generation do not release energy at the material which is therefore preserved after the observation. The objective of this thesis is to develop a multimodality platform for biology process observation by using Two Photon Excited Fluorescence, Second Harmonic Generation and Third Harmonic Generation Microscopy with the same instrument. Our group was the first one to demonstrate the acquisition of Second Harmonic Generation images in Brazil and this thesis is the first one to perform the acquisition of third harmonic generation images. These three techniques together provide complementary information respect to cell and tissue organization. While fluorescence can be specific target to some proteins, second harmonic can observe the collagen network of extra cellular matrix and the third harmonic can observe the nucleus and lipid droplets inside the cells. This thesis describe the experimental setup to perform these multimodal image acquisition, the physics behind the non linear signals, important to understand their biological mean, and shows applications of these techniques for different biological and inorganic samples / Mestrado / Física / Mestre em Física

No description available.

The main aim of this thesis is to design and develop a control unit for a three-phase direct current motor that will be able to maximize its efficiency. To accomplish this request a field oriented control combined with modified phase driving signals is used. The emphasis is put on the creation of a simple and unique solution as well as the ability to use this device in the single wheel wehicle, which previous bachelor thesis was focused on. The first part of this thesis lists some of commercially available and do-it-yourself solutions together with their attributes. The next part describes target motors and different options of how to control them. The third part focuses on the field oriented control, its individual parts and features, as well as the final solution. And finally the realization of the electrical part, firmware, PC application and necessary settings are described at the very end of the thesis.

Electric vehicle (EV) development has gone into an accelerated pace in recent years to address pressing concerns on energy security, the environment, and the sustainability of transportation. The future market success of EVs is still uncertain, but the current shift in the automotive industry is indicating a possible bright future for EVs. Because of its unique load characteristics, an extensive deployment of EVs will not only bring challenges to power systems, but will enable new opportunities as well. The objective of this work is to address the increased third harmonic currents expected with the introduction of EVs and to explore the potential of leveraging flexible EV charging to increase wind power production. Since EV chargers rely on a nonlinear power conversion process to obtain a controllable DC source from the utility AC supply, it is expected that these devices will aggravate third harmonic current issues. In fact, utility harmonic field data show that, even without EVs, distribution feeders are already experimenting elevated levels of third harmonic currents. To address present and future utility harmonic filtering needs, a practical third harmonic hybrid active filter for medium voltage (MV) applications is proposed. Its design is based on strict utility requirements of cost, reliability, and ease of system implementation. The operation and performance of the proposed filter is verified through simulations and two experimental setups, one tested at 7.2 kV. Furthermore, a system impact study of the proposed filter is performed using actual data for a typical residential/small commercial distribution feeder. Because vehicles remain stationary most of the time, EVs have the potential of being flexibly charged, providing a spectrum of opportunities for system operators. The recent increase in wind power penetration in the U.S. is raising concerns on how to accommodate this stochastic renewable energy resource in day-ahead scheduling operations. In this work, a detailed integrated day-ahead scheduling framework is developed to explore the impact of leveraging flexible EV charging to balance out the variability and uncertainty of wind power generation. It is determined that the full benefits of balancing wind power generation with flexible EV charging may not be achieved in congested power systems. A potential solution based on deploying power routers (PRs) to augment the flexibility of the transmission system is proposed. Simulation results are presented for a test system based on the IEEE 39-bus system.

Στη παρούσα διατριβή μελετούμε την αλληλεπίδραση ατόμων αλκαλίων (νατρίου-Na και καλίου-K) με σύμφωνη πηγή ακτινοβολίας (laser). Συγκεκριμένα παρουσιάζουμε: i) Την επίδραση της καταστρεπτικής κβαντικής συμβολής (destructive quantum interference), η οποία εμφανίζεται στη διαδρομή-1, του ατομικού K υπό nsec διφωτονική διέγερση. Η καταστρεπτική κβαντική συμβολή οδηγεί στη γραμμική απόκριση των εσωτερικά παραγόμενων εντάσεων των ακτινοβολιών στις μεταβάσεις των παραγόμενων πεδίων της διαδρομής-1. Το φαινόμενο αυτό μελετάται για διάφορες τιμές των παραμέτρων: της μέγιστης έντασης της διεγείρουσας ακτινοβολίας του laser, του διφωτονικού αποσυντονισμού, της ατομικής πυκνότητας και του μήκους διάδοσης των ακτινοβολιών, όταν οι δύο από τις τρείς αυτές παραμέτρους παραμένουν σταθερές. Επίσης, μελετούμε τις προυποθέσεις του κορεσμού της διαδρομής-1 για ισχυρότερη ένταση του εξωτερικού πεδίου laser και κατόπιν δείχνουμε ότι η διαδρομή-2, εμφανίζεται, έχοντας πρώτα κορεσθεί η διαδρομή-1, στις μικρές ατομικές πυκνότητες. Επιπρόσθετα, παρουσιάζουμε τις προυποθέσεις επαγωγής ενός είδους ατομικής μνήμης (optical free induction memory) όταν ο παλμός laser υποστεί απότομη πτώση στο μέγιστο του (truncated pulse). ii) Τις συνθήκες εκείνες οι οποίες ευθύνονται για την εμφάνιση αξονικής ή/και κωνικής εκπομπής της διαδρομής-1, και διαδρομής-2, αντίστοιχα, για διάφορες ατομικές πυκνότητες, υπό fsec διφωτονική διέγερση του ατομικού K. iii) Την παραγωγή ακτινοβολιών από σύμφωνη παραμετρική μίξη (parametric four-wave mixing) ή και μερικώς σύμφωνο μηχανισμό όπως η ενισχυμένη αυθόρμητη εκπομπή (amplified spontaneous emission) ή υπέρ σκέδαση- Raman (stimulated hyper-Raman scattering), όταν το nsec πεδίο laser διεγείρει με δύο φωτόνια την μετάβαση 4S1/2-6S1/2, καθώς και την μετάβαση 4S1/2-7S1/2, αντίστοιχα. Εστιάζουμε κατά μείζονα λόγο τη μελέτη μας στη διαδρομή-2, στήν μονόδρομη (unidirectional) και στήν αμφίδρομη (bidirectional) διάδοση της ακτινοβολίας του πεδίου laser. iv) Την γέννεση της κωνικής τρίτης αρμονικής (conical third harmonic generation-THG) σε μεταλλικούς ατμούς Na και K υπό fsec διέγερση. Στη περίπτωση του Na (μέσο με κανονική διασπορά) βρίσκουμε ότι η χαρακτηριστική δακτυλοειδή δομή του κώνου της τρίτης αρμονικής οφείλεται στήν επίδραση κυρίως του τανυστικού όρου πέμπτης τάξης ο οποίος σχετίζεται με την μίξη έξι κυμάτων. Ακόμα, δείχνουμε, ότι στη περίπτωση του K (μέσο με αρνητική διασπορά) η εκπομπή μακρινού πεδίου (far field emission) της κωνικής τρίτης αρμονικής, παρουσιάζει ορισμένες διαφοροποιήσεις σε σχέση με αυτή του Na. Το όλο φαινόμενο αντιμετωπίζεται φαινομενολογικά. / In the doctorate dissertation is studied the effect of the wave mixing of laser light with the internally generated fields of the alkali vapors, such as the sodium (Na) and the potassium (K) respectively. Specifically it was studied: ι) The numerical simulation of the four-level system, when a two-photon nsec field excites the transition 4S1/2-6S1/2 of potassium atom. It is shown that the destructive quantum interference is responsible for the reduction of the non-linearity of path-1, in which, the parameters of the system, such as the two-photon detuning, the atomic density and the laser maximum intensity, play an important role. Moreover the saturation of the path-1 has as a consequence the passage of the energy to the atomic path-2, which activates later than the path-1, in low atomic density of atomic K. A truncated excitation pulse is able to induced phenomena of atomic memory in which the providing excitation intensity is able to be stored in the system. The optical free induction memory (OFIM) is observed in the truncated nsec excitation of the transition 4S1/2-6S1/2. This type of atomic memory is studied via the evolution of the density matrix element s12, for specific selection of the two-photon detuning. ii) The conditions which are responsible for the axial or/and conical emission of radiation of path-1 and of path-2, respectively under the fsec two-photon excitation respectively. iii) The production of coherent (parametric four-wave mixing) or/and partially coherent (amplified spontaneous emission or stimulated hyper-Raman scattering) radiation when the nsec laser field excites with two-photons the transition 4S1/2-6S1/2, and the transition 4S1/2-7S1/2, of atomic potassium respectively. It is also studied the emissions of the path-2 in the unidirectional and the bidirectional propagation (counter-propagation) of the laser field in the nsec 4S1/2-6S1/2 two-photon excitation. iv) The conical third harmonic generation (THG) in Na and K vapor under the fsec excitation. It is proved that the third harmonic generation of Na, (normally dispersive medium), in the laser wavelength range of 1770-2200 nm, is mainly a result of six-wave mixing. The fifth order tensor term dominates against the third order term, (which is connected with the four-wave mixing process), as it is shown theoretically. In the case of Κ vapor (negative dispersion medium), in the laser wavelength range of 1200-2180 nm, the observed conical emission appears similarities and dissimilarities with the Na one respectively. The THG generation of Κ interpreted in a phenomenological way.

Cette thèse porte sur l'étude du réseau lacuno-canaliculaire (Lacuno-canalicular Network : LCN) osseux grâce à différentes techniques de microscopie optique. Le LCN correspond à l'empreinte dans la matrice osseuse du réseau ostéocytaire formé de cellules dendritiques (les ostéocytes) interconnectées. Bien qu'il joue un rôle majeur dans la formation, le remodelage et le maintien des propriétés biomécaniques de l'os, les informations sur ce réseau cellulaire dans sa globalité restent limitées. Cela provient notamment de la difficulté à caractériser ce réseau dense et complexeavec une résolution sub-micrométrique sur des échelles allant jusqu'à l'organe entier. Dans cetravail de thèse nous avons cherché à améliorer la caractérisation du LCN en utilisant deux approches : la mise en place d'une méthode d'analyse du LCN à grande échelle à partir dela microscopie confocale d'une part et l'évaluation du potentiel de la microscopienon linéaire pour l'étude du LCN d'autre part.Dans un premier temps nous avons mis au point un protocole allant de la préparation des échantillons jusqu'au traitement des images et à l'analyse des données afin d'optimiser l'imagerie confocale des tissus osseux dans le but d'obtenir une analyse quantitative du réseau à grande échelle. Les résultats préliminaires mettent en évidence une grande variabilité des paramètres du réseau à toutes les échelles révélant la complexité de celui-ci. Cette analyse a été mise en pratique afin d'étudier les variations du LCN à l'échelle d'un fémur entier de souris.Dans un second temps, nous avons évaluer le potentiel de la microscopie optique non linéaire et notamment de la génération de troisième harmonique (THG) pour l'imagerie et l'étude du LCN. Nous avons tout d'abord montré la possibilité de visualiser le LCN, sans marquage fluorescent, grâce à la microscopie THG. A partir de cette preuve de principe nous avons expliqué l'origine des contrastes observés dans l'os par microscopie THG : un signal provenant des porosités et permettant de visualiser le réseau et un signal de fond structuré provenant des interfaces entre les fibrilles de collagène. Nous avons également évaluer les possibilités de la combinaisons de signaux non linéaires, principalement ceux de la THG et de la SHG (génération de seconde harmonique) qui permettent de visualiser simultanément le réseau et la matrice de collagène respectivement. Une corrélation entre la structure du réseau et l'organisation du collagène a pu être établie grâce à la visualisation de ces deux signaux sur de grandes échelles. Enfin des résultats quantitatifs sur le LCN ont pu être obtenus à partir des images THG permettant une étude des effets de la micro-gravité sur la structure de ce réseau. / This thesis focuses on the study of bone lacuno-canalicular network (LCN) using different optical microscopy techniques. The LCN is the porosity network in the bone matrix where the cellular network lie. It is formed of dendritic cells: the osteocytes which are connected to each other. Although it plays a major role in the formation, remodeling and maintenance of biomechanical properties of bone, only little is known about this network as a whole. This can be explain by the difficult characterization of such a dense and complex network with sub-micron resolution and scales up to the entire organ. In this work we have sought to improve the characterization of the LCN using two approaches: the development of a method to analyse the network on large scale using confocal microscopy on one hand, and the assessment of the potential of non linear microscopy technique to study the LCN on the other hand.First, we have developed a protocol from sample preparation to image processing and data analysis to optimize confocal imaging of bone tissue in order to obtain a quantitative large scale analysis of the network. Preliminary results show a wide variation of network parameters at all scales revealing its complexity. This analysis was then used in order to assess changes in the LCN across an entire mice femur.Secondly, we study the potential of the non-linear optical microscopies especially the third harmonic generation (THG) microscopy for imaging and the study of the LCN. Initially, we demonstrated the ability to visualise the LCN without fluorescent labelling using THG microscopy. From this proof of concept we explained the origin of the different ThG microscopy contrasts observed in bone tissue: a signal from the porosities allowing to visualize the network and a structured background signal generated at the interfaces between collagen fibrils. We also assess the possibilities of combinations between different non-linear signals, mainly THG and SHG (second harmonic generation) that can simultaneously image the network and the collagen matrix respectively. A correlation between the network structure and collagen organization has been established using the visualization of these two signals over large scales. Finally quantitative parameters of the LCN were obtained from THG images and applied to study the effects of microgravity on the cellular network structure.