L’holographie est souvent considérée comme la technologie de visualisation 3D la plus prometteuse, puisqu'elle fournit l'illusion du relief la plus naturelle et la plus réaliste possible. Toutefois, pour trouver application dans le domaine de la visioconférence ou de la téléprésence, les méthodes de génération numérique d'hologrammes doivent produire des scènes réalistes avec une forte illusion de profondeur, et ce en temps réel. Cette thèse se situe dans ce contexte et est organisé en deux parties. Dans la première partie de ce travail, nous avons proposé deux algorithmes de synthèse d'hologrammes permettant de se rapprocher du temps réel. Tout d'abord, nous avons développé une méthode combinant deux approches complémentaires: les approches point-source et wave-field. Alors que les méthodes de l'état de l'art réduisent la complexité de calcul de ces deux approches indépendamment, notre méthode tire parti de chacune d'entre elles. De cette manière, le temps de calcul de l'hologramme a été réduit de plus de 65% par rapport aux méthodes point-source et wave-field conventionnelles. Deuxièmement, nous avons cherché à accélérer cette méthode hybride en supprimant les redondances temporelles entre les trames consécutives d'une vidéo 3D. Pour chaque image, l'algorithme détecte les changements dans la scène et met à jour l'hologramme des points affectés. Étant donné que seules de petites régions de l'hologramme sont mises à jour, la charge de calcul est considérablement réduite, permettant le calcul d’hologrammes couleur à 60 images par seconde. Dans la deuxième partie de ce travail, nous avons proposé deux algorithmes afin d'améliorer la qualité visuelle des scènes. Tout d'abord, nous avons perfectionné la méthode hybride pour tenir compte des occultations dans la scène. Pour cela, nous avons conçu une méthode efficace pour le calcul de l'occultation d'une onde lumineuse par un point. Cette méthode reproduit les occultations sans augmenter de manière significative le temps de calcul de la méthode hybride originale. Enfin, nous avons proposé une méthode pour le calcul d'un hologramme à partir de données multivue-plus-profondeur (MVD) avec prise en compte des réflexions spéculaires. Selon cette méthode, la géométrie de la scène est reconstruite à partir des données MVD sous la forme d'un nuage de points, ce qui permet de n'utiliser que quelques projections de la scène. En outre, afin de tenir compte de réflexions spéculaires, chaque point de la scène est considéré avoir une émission différente selon les directions. Enfin, la lumière émise par la scène est propagée dans le plan de l'hologramme. Les résultats expérimentaux montrent que cette méthode reproduit tous les indices de la profondeur et l'illumination précise de la scène avec une complexité de calcul réduite. / Holography is often considered as the most promising 3D visualization technology, since it can produce the most realistic and natural depth illusion to the naked eye. However, in order to have application in the field of videoconferencing or telepresence systems, hologram synthesis methods should be able to produce realistic 3D scenes with strong depth illusion in real-time. This thesis falls within this context and is organized into two parts. In the first part of this work, we investigated two novel algorithms in order to get closer to real-time computation. First, we designed a fast hologram calculation method by combining two approaches which complement one another: the point-source and wave-field approaches. Whereas previously proposed methods reduced the computational complexity of these approaches independently, our method takes advantages from both of them. By this way, the hologram calculation time has been reduced by more than 65% compare to the conventional point-source and wave-field methods. Second, we further accelerated this hybrid method by removing temporal redundancies between consecutive frames of a 3D video. For each video frame, the algorithm detects changes in the scene and updates the hologram of only affected scene points. Since only small regions of the hologram are updated at each video frame, this method allows the computational burden to be dramatically reduced, enabling the computation of colorful video holograms at 60 frames per second. In the second part of this work, we proposed two algorithms in order to enhance the visual quality of displayed scenes. First, we improved the hybrid method to take into account occlusions between objects in the scene. To this end, we designed an efficient algorithm for light shielding between points and light waves. Experimental results revealed that this method provides occlusion effect without significantly increasing the hologram calculation time of the original hybrid method. Finally, we proposed a hologram computation method from Multiview-plus-depth (MVD) data with rendering of specular reflections. In this method, the 3D scene geometry is first reconstructed from the MVD data as a layered point-cloud, enabling the use of only a few perspective projections of the scene. Furthermore, in order to take into account specular reflections, each scene point is considered to emit light differently in all the directions. Finally, light scattered by the scene is numerically propagated towards the hologram plane in order to get the final hologram. Experimental results show that the proposed method is able to provide all the human depth cues and accurate shading of the scene with reduced computational complexity.

A reflectance volume holographic imaging (VHI) endoscope has been designed for simultaneous in vivo imaging of surface and subsurface tissue structures. Prior utilization of VHI systems has been limited to ex vivo tissue imaging. The VHI system presented in this work is designed for laparoscopic use. It consists of a probe section that relays light from the tissue sample to a handheld unit that contains the VHI microscope. The probe section is constructed from gradient index (GRIN) lenses that form a 1: 1 relay for image collection. The probe has an outer diameter of 3.8 mm and is capable of achieving 228.1 lp/mm resolution with 660-nm Kohler illumination. The handheld optical section operates with a magnification of 13.9 and a field of view of 390 mu m x 244 mu m. System performance is assessed through imaging of 1951 USAF resolution targets and soft tissue samples. The system has also passed sterilization procedures required for surgical use and has been used in two laparoscopic surgical procedures. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22992号 / 理博第4669号 / 新制||理||1670(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 高柳 匡, 教授 青木 慎也, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Creating compact, efficient, highly-controllable optical systems has been one of the central goals of optics and photonics research. Integrated photonics provides a powerful platform for manipulating light efficiently and flexibly by guiding light in waveguide circuits on chip. Among the rich family of integrated photonic devices, integrated optical modulators and wavefront generators are two types of components for a great many applications such as optical communications, VR/AR displays, and LiDAR. Current approaches to creating these two types of devices – integrated optical modulators based on waveguides, active wavefront transceivers based on phased arrays, and passive wavefront transceivers based on grating couplers or integrated metasurfaces – suffer from large footprint, high power consumption, low beam quality, and limited controllability. It is desirable to improve the performance of such devices by exploring new device physics and architectures.In this thesis, we propose and investigate several novel approaches for efficient optical modulation and wavefront manipulation using integrated photonics. First, we show that efficient optical phase modulation can be achieved using a micro-resonator operating in the strongly over-coupled regime. Theoretical analysis, simulations, and experimental demonstrations of thermally tuned silicon nitride adiabatic micro-ring resonators operating at the visible and near-infrared wavelengths are conducted. Compared with traditional waveguide-based devices, our resonator-based phase modulators operating at the visible wavelengths showed order-of-magnitude reductions in both device footprint and power consumption. Through a statistical study of the device performance, our adiabatic micro-ring device architecture also showed significantly improved robustness against fabrication variations when compared with the regular micro-ring architecture. Second, we invent a new category of integrated wavefront-shaping devices – leaky-wave metasurfaces – that possess the simple form factor of a grating coupler and the capability of complete wavefront manipulation over all the four optical degrees of freedom: amplitude, phase, polarization ellipticity, and polarization orientation. The working principle of the leaky-wave metasurfaces is based on symmetry-broken photonic crystal slabs supporting quasi-bound states in the continuum (q-BICs). We extended the mechanism of q-BICs excited by free-space planewaves into q-BICs excited by guided waves, and developed a semi-analytical model describing the mapping between the four structural parameters and the four optical parameters of a meta-unit. We experimentally demonstrated multiple leaky-wave metasurface devices that convert light confined in an optical waveguide to an arbitrary optical pattern in free space, realizing custom polarization control, phase-amplitude control, and complete wavefront control, and validating the theory and capability of this platform. Lastly, we explore strategies to optimize the beam quality and efficiency of integrated optical phased arrays. We show that a two-dimensional disordered hyperuniform array layout is promising for generating a radiation pattern with high directionality with performance surpassing uniform arrays, constrained random arrays, and non-redundant arrays. We experimentally demonstrated a passive 32-channel phased array operating at the blue wavelength that showed a high percentage of power in the main beam and suppressed side lobes. We further propose and discuss the use of efficient, resonator-based modulators in phased arrays to improve the system compactness, power efficiency, and scalability. The approaches we investigated in this thesis provide a concrete set of solutions for interfacing free-space optics and integrated photonics. These two platforms have traditionally been studied by investigators from different subfields of optics and have led to commercial products addressing different needs. Our work suggests new ways to create “hybrid” systems consisting of partly integrated photonics and partly free-space optics and utilize the best of both worlds to address many emerging applications such as quantum optics, optogenetics, sensor networks, inter-chip communications, and holographic displays.

As three-dimensional (3D) imaging and fluorescence techniques become standard in optical microscopy, novel approaches to 3D fluorescence microscopy are emerging. One such approach is based on the incoherent holography technique called optical scanning holography (OSH). The main advantage of OSH-based microscopy is that only a single two-dimensional (2D) scan is required to record 3D information, whereas most current 3D microscopes rely on sectioning techniques. To acquire a 3D representation of an object, current microscopes must physically scan the specimen in a series of 2D sections along the z-axis. In order to record holograms by OSH, the fluorescent specimen is scanned with an optically heterodyned laser field consisting of a Fresnel zone pattern. A unique acousto-optic modulator configuration is employed to generate a suitable heterodyne frequency for excitation of the fluorescent object. The optical response of a solution containing a high concentration of 15 um fluorescent latex beads to this type of excitation field has been recorded. In addition, holograms of the same beads have been recorded and reconstructed. To demonstrate the 3D imaging capability of the technique, the hologram includes beads with longitudinal separation of about 2 mm. A detailed comparison of 3D fluorescence microscopy by OSH and the confocal approach was conducted. Areas for comparison were 3D image acquisition time, resolution limits and photobleaching. The analysis shows that an optimized OSH-based fluorescence microscope can offer improved image acquisition time with equal lateral resolution, but with degraded longitudinal resolution when compared to confocal scanning optical microscopy (CSOM). For the photobleaching investigation, the parameter of concern is the fluence received by the specimen during excitation, which takes into account both the irradiance level and the time of illumination. Both peak and average fluence levels are addressed in the comparison. The analysis shows that during a 3D image acquisition, the OSH system will deliver lower peak fluence but higher average fluence levels to the specimen when compared to CSOM. / Ph. D.

Optical scanning holography, which was proposed by Poon[1], is a fascinating technology to record holographic information. The technique is applied in the operation of scanning holographic microscopy to record the entire three-dimensional volume of a biological specimen in the form of a hologram. With the data captured, a digital reconstruction or decoding is used to reconstruct the hologram of that such specimen. An accurate reconstruction of the recorded data provides with an in-depth analysis in the area where random noise and other imperfection effects may occur. In this thesis, three different approaches of reconstruction process are presented to provide in high-resolution a comparison between theoretical and experimental reconstruction a hologram of fluorescent beads. The first approach is to use only the experimental pinhole hologram recorded to correlate with the hologram of the object to give the reconstruction of the section. The second approach is to use the propagated pinhole hologram to reconstruct at an arbitrary depth. Finally, the third approach is to reconstruct without using the experimental pinhole hologram but with diffraction theory. Comparing these results in high-resolution gives us analysis of the reconstruction noise due to optical aberration. / Master of Science

A holographic recording method using an optical heterodyne 2-D scanning technique for 3-D imaging of fluorescent objects in turbid media is described and experimentally demonstrated. For the first time, 3-D imaging of fluorescentobjects in turbid media by a holographic method is achieved, and the diffused photon rejecting process through a heterodyne technique is analyzed. We also propose and realize a multiplexing and a digital decoding method for removing twin-image noise in optical scanning holography. The holographic method studied can be applied to 3-D biomedical imaging of fluorescent objects in turbid media as well as diffusely reflecting objects. / Master of Science

No description available.

Orientador: Prof. Dr. Marcos Roberto da Rocha Gesualdi / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Física, 2017. / Sistemas de instrumentação cientíca vem sendo poderosas ferramentas para viabiliza- ção e comprovação de modelos em física teórica, bem como, para geração de produtos tecnológicos. Nesse sentido, as técnicas de Interferometria e Microscopia Holográca se mostram como poderosos métodos ópticos para observação de fenômenos perturbativos, na análise da fase de frentes de onda ópticas, em ensaios não destrutivos de análise de superfícies e aferição de sistemas ópticos. Particularmente, as técnicas holográcas em tempo real se apresentam favoráveis em relação às técnicas convencionais de análise de superfícies e frentes de onda, pois permitem a análise, visualização e monitoramento in situ dos sistemas estudados com precisão e conabilidade. Por outro lado, as técnicas de Holograa Computacional e Fotorrefrativa, nas quais cristais fotorrefrativos são usados como meio de registro holográco, tem se mostrado promissoras para geração de feixes ópticos especiais. Desta forma, o objetivo deste trabalho foi estudar e aplicar os métodos da Interferometria e Microscopia Holográca (Digital e Fotorrefrativa) para análise de intensidade e fase em feixes ópticos especiais (não-difrativos) e superfícies tridimensionais micro-estruturadas. Desenvolvemos para esses ns, um arranjo de Interferometria Hologr áca Digital e Fotorrefrativa para geração e análise de feixes ópticos e um sistema de Microscopia Holográca Digital e Fotorrefrativa para análise micro-estruturas (retículos e células sanguíneas). Os resultados obtidos estão de acordo com o previsto teoricamente, permitindo excelente perspectiva de aplicações desses sistemas na análise e caracterização de feixes ópticos e superfícies micro e nano-estruturadas. / Scientic instrumentation systems are powerful tools for feasibility and verication of models in theoretical physics, as well as for the generation of technological products. In this sense, Holographic Interferometry and Holographic Microscopy are shown as powerful optical methods for observing perturbative phenomena, in the analysis of the phase of wavefronts, non-destructive testing for surface analysis and optical systems admeasurement. Notably, real-time Holographic techniques are favorable compared to conventional surface analysis techniques, since they allow the analysis, visualization and in situ monitoring of the studied systems with precision and reliability. On the other hand, Computational and Photorefractive Holographic techniques, in which photorefractive materials are used as holographic recording media, are promising techniques for special optical beams generation. Thus, the objective of this research project was to study and apply the methods of Holographic Interferometry and Holographic Microscopy (Digital and Photorefractive) for the analysis of intensity and phase of special optical beams (non-diractive) and micro-structured three-dimensional surfaces. For these purposes, we developed a Digital and Photorefractive Holographic Interferometry arrangement for the generation and analysis of optical beams and a Digital and Photorefractive Holographic Microscopy for micro-structures analysis (resolution targets and blood cells). The obtained results are in agreement with those predicted theoretically, allowing an excellent perspective of applications of these systems in the analysis and characterization of optical beams and micro and nano-structured surfaces.

Este trabalho teve como objetivo a aplicação do Microscópio Holográfico Digital para análise de amostras biológicas, por meio de imagens de parâmetros físicos e informação quantitativa de uma amostra, gerados através de hologramas digitais, o que não ocorre na holografia clássica. O processamento e análise dos hologramas digitais foi efetuada por um programa escrito por meio do software MatLab, empregando o método de Dupla Propagação. São explicados outros métodos para tratamento de hologramas digitais, presentes no programa. O método de Dupla Propagação foi discutido, destacando suas vantagens frente aos outros métodos. Foi aplicado o método de Volkov para a retirada de ambiguidade de fase. O processo de montagem do Microscópio Holográfico Digital foi descrito, por apresentar modificações em relação ao protótipo inicial adotado. Sete amostras foram analisadas no Microscópio Holográfico Digital, três de calibração e quatro para análise - sangue e solução concentrada de proteína denominada Beta2 Glicoproteína tipo I, ou Beta2-GPI. Para calibração, foram realizados testes de formação de imagem, realizando comparação em quatro microscópios descritos e explicados em funcionamento e princípio envolvidos na formação de imagens, utilizando a mesma amostra; e verificação das dimensões de uma amostra, por meio de medição usando ferramentas disponíveis no programa. Uma amostra de sangue de um indivíduo heterozigoto para Hemoglobina S (anemia falciforme) e uma amostra de sangue de um indivíduo homozigoto para hemoglobina A1 (controle normal) foram empregadas na forma de filmes líquidos secos sobre lâminas de vidro (extensão sanguínea). O uso de fixação foi avaliado com a amostra controle. Foram geradas imagens em duas e três dimensões para as amostras biológicas, reproduzindo as estruturas morfológicas de cada. Para a proteína Beta2-GPI, a análise envolveu somente imagens, sem extração de valores; apesar disso, os resultados mostraram possibilidades de aplicações em estudos futuros. Grandezas físicas foram calculadas para dois dos componentes sanguíneos (Plasma e Eritrócito), mostrando valores próximos daqueles conhecidos anteriormente. Entretanto, alguns valores foram considerados estimativas novas, por não se conhecer, até o momento, nenhum cálculo efetuado anteriormente. A análise comprovou a formação de imagens e a capacidade de mensuração oferecida pelo aparelho. Devido ao parâmetro da fase, foi possível extrair informações em três dimensões. / This work aimed the implementation of the Digital Holographic Microscope for the analysis of biological samples, using physical parameters images and quantitative data from a sample, both generated through digital holograms, which does not occur in Classical holography. Processing and analysis of holograms were performed by a program written using the MatLab software, applying the Double Propagation method. Other methods for the treatment of digital holograms were explained. The Double Propagation method was discussed, highlighting their advantages over other methods. The method of Volkov was applied for removing phase ambiguity. The Digital Holographic Microscope assembly process was described, because of the modifications made to the initial prototype adopted. Seven samples were analyzed in the digital holographic microscope, three of them for calibration and the other to the analysis - blood and a concentrated solution of a protein called type I Beta2 Glycoprotein, or Beta2-GPI. Calibration tests were made by observing and comparing four image microscopes, described and explained in operation and principles involved in the formation of images, using the same testing sample; and checking the dimensions of another sample through measurement, using digital tools available in the program. Hb S heterozygous (Sickle Cell disease) and Hb A1 homozygous (Control) blood samples were prepared in microscope slide glasses. Images were acquired in two and three dimensions for biological samples, reproducing their morphological structures. For Beta2-GPI, the analysis involved only images, and no values were extracted; nevertheless, the results showed potential applications in future studies. Physical quantities were calculated for two blood components (Plasma and Erythrocyte), showing values closer to those previously known. However, some values were considered new estimates, because there is no knowledge of any calculation made previously, until now, using Digital Holographic Microscopy. The analysis proved the formation of images and the measurement capacity offered by the apparatus. Due to the phase parameter, we were able to extract information in three dimensions.