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Cavity Techniques for Volume HolographyMiller, Bo Elliot, Miller, Bo Elliot January 2016 (has links)
Volume Holographic Data Storage Systems (HDSS) has been of interest for almost seven decades, and are now considered as a viable option for Write Once Read Many (WORM) cold data storage applications. Thanks to the Bragg selectivity of thick volume holograms, HDSS stores several hundreds of holograms on top of each other, called multiplexed data pages, by which data recording density can be substantially increased compared to surface recordings. On the other hand, signal intensity upon reconstruction of such multiplexed data pages inversely scales with number of multiplexing squared. Therefore, longer detection time and/or a high power laser along with a large dynamic range material is needed to make HDSS a truly viable "fast and high density" option for WORM applications. Historically, the trade-off between data density and data rate is well recognized. The challenge has been partially solved by continuous efforts such as improvement of materials, optical architectures, opto-mechanical systems and signal processing [1,2]. In this dissertation, we provide an additional pathway for HDSS to further increase both data density and transfer rates which is Cavities Enhancement Techniques for HDSS, to overcome the fundamental tradeoff. Key ideas are: recycling light with cavity to enhance data rate, and increasing number of multiplexing by combining cavity-eigenmode multiplexing, a subset of orthogonal phasecode multiplexing, with angular multiplexing. Based on this idea, we design and demonstrate Cavity-enhanced HDSS in such a way that we increase data rate and/or data density by at least factor of 2 while taking advantage of previous improvements as they are, or only with the minimum amount of modifications. In Section 1, we review history of HDSS and summarize the latest research results of HDSS and requirements on modern optical data storage systems as they relate to our solutions. In Section 2, theory of volume holography is reviewed by emphasizing understanding of angular and orthogonal phase code multiplexing. In Section 3 the theory of cavity enhanced reference arms is presented. We discuss how cavities provide a coherent boost to the beam power, which can be used in recording to alleviate source power requirements and/or increase the data recording rate and demonstrate the enhancement experimentally. Beyond basic enhancement, cavities also enable orthogonal phase code multiplexing via cavity eigenmodes. In Section 4, we experimentally demonstrate angular and orthogonal phase code hybrid multiplexing to overcome the limitation of the maximum number of multiplexing imposed by the geometrical constraints of angular multiplexing. In Section 5, novel aspects of the research are discussed in conjunction with the application of the technology for commercial use. Conclusions and future research direction are addressed in Section 6.
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Trojrozměrná rekonstrukce obrazu v digitální holografické mikroskopii / Three-dimensional reconstruction of image in digital holographic microscopyTýč, Matěj Unknown Date (has links)
This thesis deals with the topic of 3D image processing for digital holographic microscopy - numerical refocusing. This method allows to perform mathematically accurate defocus correction on image of a sample captured away from the sample plane and it was applicable only for images that were made made using coherent illumination source. It has been generalized to a form in which it is also applicable to devices that use incoherent (non-monochromatic or extended) illumination sources. Another presented achievement concerns hologram processing. The advanced hologram processing method enables obtaining more data mainly concerning precision of quantities from one hologram — normally, one would have to capture multiple holograms to get those. Both methods have been verified experimentally.
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Environmental stability study of holographic solar spectrum splitting materialsChrysler, Benjamin D., Ayala Pelaez, Silvana, Wu, Yuechen, Vorndran, Shelby D., Kostuk, Raymond K. 23 September 2016 (has links)
In this study the impact of outdoor temperature variations and solar illumination exposure on spectral filter material and holographic optical elements is examined. Although holographic components have been shown to be useful for solar spectrum splitting designs, relatively little quantitative data exist to demonstrate the extent to which these materials can withstand outdoor conditions. As researchers seek to investigate practical spectrum splitting designs, the environmental stability of holographic materials should be considered as an important factor. In the experiment presented, two holographic materials, Covestro Bayfol HX photopolymer and dichromated gelatin, and 3M reflective polymer filter materials are exposed to outdoor conditions for a period of several months. The environmental effect on absorption, spectral and angular bandwidth, peak efficiency, and Bragg matching conditions for the holograms are examined. Spectral bandwidth and transmittance of the 3M reflective filter material are also monitored. Holographic gratings are recorded, measured, and mounted on glass substrates and then sealed with a glass cover plate. The test samples are then mounted on a photovoltaic panel to simulate realistic temperature conditions and placed at an outdoor test facility in Tucson, Arizona. A duplicate set of holograms and 3M filter material is stored as a control group and periodically compared over the test period.
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"Influência dos materiais restauradores protéticos na transmissão da carga oclusal : método da interferometria holográfica" / Influence of prosthetic restorative materials at occlusal load transmission. Holographic Interferometry MethodUono, Carla Rumi Hanada 04 October 2005 (has links)
Apesar dos pesquisadores afirmarem que os materiais odontológicos restauradores, devido às suas diferentes propriedades mecânicas, influenciam na transmissão da carga para os tecidos de suporte, não foi encontrada comprovação científica concludente. Os trabalhos de análise da distribuição da carga oclusal com diferentes materiais de reconstrução protética não são concordantes em seus resultados. Assim, diante da importância da seleção de materiais restauradores protéticos no prognóstico da reabilitação oral, este trabalho se propôs a estudar a influência de coroas protéticas metalo-cerâmica e de resina, cimentadas no canino, na transmissão de tensões para o tecido ósseo em mandíbulas frescas de cães, utilizando o método de interferometria holográfica de dupla exposição. Seis hemi-mandíbulas frescas de cães da espécie Canis familiares foram fixadas em um dispositivo para garantir a invariabilidade da força aplicada durante o experimento. Uma carga de 0,98 N foi aplicada sobre as coroas, seguindo o longo eixo do dente. Pelo método de interferometria holográfica, foram obtidos 12 hologramas, 6 para cada grupo de amostras. As coroas metalo-cerâmicas apresentaram maior deslocamento, com movimento de intrusão no alvéolo, em relação às de resina. Os microdeslocamentos resultantes nas hemimandíbulas demonstraram comportamentos semelhantes de deflexão, porém, não foram encontradas diferenças estatisticamente significantes na distribuição das tensões ao osso, com relação aos dois tipos de coroas consideradas, demonstrando a influência da presença do ligamento periodontal. / Although researches assert that restoring dental material, due to their different mechanical properties, influences at load transmission to support tissues, it was not find any conclusive scientific evidence. Researches with finite element, implants and different prosthetic reconstruction material do not have an agreement in terms of results. So, considering the importance of prosthetic restoring material selection on oral rehabilitate prognosis, this assignment studied the influence of metaloceramic and resin prosthetics crowns, cemented on canine, during stress transmission to bony tissue of post-mortem dog mandibles, using double exposure holographic interferometry method. Three fresh mandibles were split into 6 hemi-mandibles, which were fixed in a proper device in order to assure the same applied force during the whole experiment. A 0,98 N load was applied to the crowns, following the long axis of the tooth. It was collect 12 holograms, 6 for each sample group. Metaloceramic crowns presented larger intrusion micromovement in the alveolus, comparing that of resin ones. The resulting micromovings in the hemimandibles presented similar deflecting behaviour. However, significant statistical differences on bone tension distribution have not been found, concerning the two types of previously referred crowns, demonstrating the influence of periodontal ligament.
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Estudo de esforços mastigatórios utilizando técnica de interferometria holográfica\" / Study masticatory effort using holographic enterferometry techniqueOliveira, Glaura Caroena Azevedo de 05 March 2007 (has links)
A interferometria holográfica é um poderoso método óptico para observação de fenômenos perturbativos e na análise de superfícies, sendo extremamente útil em aplicações em pesquisa básica, biomédicas e tecnológicas. Os cristais fotorefrativos se apresentam como um meio atrativo para registro de hologramas. O fenômeno que caracteriza esses cristais é o efeito fotorrefrativo. Tal efeito consiste na modulação do índice de refração através de fotoindução e efeito eletro-óptico linear (Efeito Pockels), o que permite o registro de hologramas de fase em volume. Entre as características que recomendam os cristais fotorrefrativos para interferometria holográfica podemos citar: o processo de registro e leitura ocorre de maneira dinâmica através da técnica de mistura de duas ondas; o fato de serem meios revers´?veis dispensando processamento químico e a boa resolução implicando imagens holográficas de boa qualidade. Analisamos as diversas tensões que ocorrem no processo mastigatório, estudando principalmente a concentração de cargas e as dissipações nesse processo, utilizando a técnica holográfica de dupla exposição e o cristal fotorrefrativo Bi12SiO20 (BSO), da família das Silenitas, como meio de registro. O estudo em crânio seco e a simulação dos principais feixes dos músculos da mastigação permitem realizar a contração dos mesmos, com aproximação melhor que os métodos de elementos finitos e resinas fotoelásticas, em estruturas anisotrópicas como o crânio. / The holographic interferometry is a powerful optical method for observation of the disturbance phenomena and in the analysis of surface, being extremely useful in application in basic research, biomedical and technological. The photorefractive crystals present as an attractive holographic recording medium. The phenomenon that characterize these crystals is the photorefractive effect. Such effect consistis of the index of refraction modulation grating via the linear eletro-optic effect (the Pockels effect) and photoindution, that it allow phase holographic recording in volume. Among the characteristics that admit the photorefractive crystals for holographic interferometry we can cite: recording and reading tecniques to occur in dynamics way through the tecnique of two-wave mixing, it is reversible medium resulting holographic images of good quality. We analyze the varied strains that occur in the masticatory process, mainly studying the load concentration and the dissipation in this process, using the double-exposure holographic technique and the photorefractive crystals Bi12SiO20 (BSO), of the sillenite family, as holographic recording medium. The study in dry skull and the simulation of main beams of the mastication muscles allow to realize the concentration of the same ones, with better approach than the methods of finite elements and photoelastics resins, in anisotropic structures as the skull.
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Development of high-speed digital holographic shape and displacement measurement methods for middle-ear mechanics in-vivoRazavi, Payam 28 March 2018 (has links)
The middle ear plays an integral role in the normal hearing process by transforming sound energy from the air inside the ear canal into vibrations of the inner-ear fluid, and a malfunction in any middle-ear component can lead to significant hearing loss. Despite decades of research on the Tympanic Membrane (TM or eardrum), the transformation of sound energy into ossicular mechanical vibrations is not yet well understood. Part of this is because the available clinical and research tools provide insufficient data to understand the complexities of this transformation. The data insufficiency arises due to methodological, technological, and physiological limitations such as required nanometer and microsecond spatio-temporal resolutions of the sound-induced TM motions. Although holographic methods provide nondestructive non-contact measuring capabilities that satisfy most of the constraints for TM measurements, the influence of large submillimeter scale physiological motions in live samples produced by heartbeat and breathing can result in near complete saturation of TM holograms. In this Dissertation, a new high-speed correlation interferometry holographic method is proposed that can compensate for the effects of physiological noise using an open-loop control configuration. Preliminary animal measurements with the proposed method demonstrate the necessary accuracy and precision to measure the motion of the entire TM produced by short- duration (≥1 kHz) transient stimuli. Such rapid measurements reduce the effect of the longer and slower environmental and physiologic noises, and enable clinical applications. In the second part of this Dissertation, a novel multiple wavelength high-speed holographic interferometric shape measurement method is incorporated into the high-speed displacement measurements. The method uses the imaging optics of the displacement measurement system to perform shape and orientation measurements. Displacement and shape measurements can be made in less than 200 msec and allow computation of true surface-normal displacements. The surface-normal measurements are independent of the direction of observation, which helps comparisons of measurements made after changes in TM orientation or location. The results enable accurate and precise shape and displacement measurements for use in applications such as modal and finite element analyses, additive manufacturing of prosthetic TM grafts, clinical diagnosis, hearing rehabilitation, as well as optimization of hearing devices. In addition, measured shape parameters such as curvature, depth of cone etc., can help us understand TM mechanics and contribute to quantitative diagnostic assessments.
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Desenvolvimento da microscopia holográfica digital por reflexão para avaliação 3D de superfícies. / Development of digital holographic microscopy by reflection for 3D surface evaluation.Valin Fernández, Meylí 08 December 2017 (has links)
Dentre dos procedimentos geradores de perfil óptico encontra-se a microscopia holográfica digital. Esta ferramenta interferométrica surgiu da ideia inicial proposta por D. Gabor sobre holografia, a qual permite mediante o registro da interferência de campos ópticos coerentes, guardar e extrair informações de imagens. A microscopia holográfica digital permite a análise de objetos com resoluções transversais semelhantes às obtidas por microscopia óptica, e ainda, possui a vantagem pela natureza da holografia de permitir realizar análises através do acesso a valores quantitativos de fase. Apresentam-se neste trabalho os conceitos básicos da holografia digital e da microscopia holográfica digital, com o objetivo, de introduzir o desenvolvimento de uma metodologia para a implementação da microscopia holográfica digital por reflexão para o controle dimensional de objetos e determinação da rugosidade superficial de amostras de aço. Os hologramas são obtidos mediante uma instalação óptica, que consiste em um interferômetro de Michelson por reflexão com o uso de uma lente objetiva de microscópio e uma câmera CCD sem lente. Para a reconstrução das imagens de contraste de fase são utilizadas técnicas numéricas que capacitam à microscopia holográfica digital para a supressão do termo de ordem zero, controle da resolução de pixel, desmodulação da fase óptica, determinação dos mapas de intensidades e fase, filtragem e compensação de aberrações dos hologramas obtidos. As reconstruções numéricas dos feixes objeto e referência são realizadas utilizando o método de dupla propagação. Foi desenvolvido um algoritmo que apresenta a imagem de contraste de fase com base num critério de distância a partir de um único holograma. Desta forma o programa utilizado permite a realização de medições quantitativas das dimensões dos objetos e da rugosidade superficial de amostras de aço, assim como, a representação em 3D da imagem de fase reconstruída com resultados validados através de um perfilômetro óptico 3D sem contacto modelo CCI-MP. / Among the procedures generating optical profile is the digital holographic microscopy. This interferometric tool arose from the initial idea proposed by D. Gabor on holography, which allows by recording the interference of coherent optical fields, save and extract information from images. Digital holographic microscopy allows the analysis of objects with transversal resolutions similar to those obtained by optical microscopy, and also has the advantage of the nature of holography to allow to perform analyzes through the access to quantitative phase values. This paper presents the basic concepts of digital holography and digital holographic microscopy, with the objective of introducing the development of a methodology for the implementation of digital holographic microscopy by reflection for the dimensional control of objects and determination of surface roughness of samples of steel. The holograms are obtained by means of an optical installation consisting of a Michelson interferometer by reflection using an objective microscope lens and a lensless CCD camera. For the reconstruction of phase contrast images, numerical techniques are used that enable digital holographic microscopy to suppress the zero-order term, control pixel resolution, optical phase demodulation, determination of intensity and phase maps, filtering and compensation of aberrations of the obtained holograms. Numerical reconstructions of the object and reference beams are performed using the double propagation method. An algorithm has been developed that presents the phase contrast image based on a distance criterion from a single hologram. In this way the program used allows the realization of quantitative measurements of the object dimensions and the surface roughness of steel samples, as well as the 3D representation of the reconstructed phase image with results validated through a 3D contactless optical profilometer model CCI- MP.
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Liquid Crystal on Silicon Displays Characterization for Diffractive Applications and for Holographic Data Storage in Photopolymers / Caracterización de pantallas LCoS para aplicaciones en óptica difractiva y almacenamiento holográfico de información en fotopolímerosMartínez Guardiola, Francisco Javier 23 July 2015 (has links)
In this PhD Thesis I present some methods for characterizing PA-LCoS microdisplays. It is useful to fully characterize this type of devices for evaluating its performance required in different applications. We have tested its validity in different applications such as diffractive optics elements (DOEs). Finally we apply these microdisplays in a full holographic data storage scheme using a photopolymer as holographic recording medium. We evaluate the capability of PVA/AA photopolymer for this holographic data storage system that incorporates as a novelty a convergent correlator geometry.
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Three-Dimensional Microscopy by Laser Scanning and Multi-Wavelength Digital HolographyKhmaladze, Alexander 12 September 2008 (has links)
This dissertation presents techniques of three-dimensional microscopy. First, an economical method of microscopic image formation that employs a raster-scanning laser beam focused on a sample, while non-imaging detector receives the scattered light is presented. The images produced by this method are analogous to the scanning electron microscopy with visible effects of shadowing and reflection. Compared to a conventional wide-field imaging system, the system allows for a greater flexibility, as the variety of optical detectors, such as PMT and position-sensitive quadrant photodiode can be used to acquire images. The system demonstrates a simple, low-cost method of achieving the resolution on the order of a micron. A further gain in terms of resolution and the depth of focus by using Bessel rather than Gaussian beams is discussed.
Then, a phase-imaging technique to quantitatively study the three-dimensional structure of reflective and transmissive microscopic samples is presented. The method, based on the simultaneous dual-wavelength digital holography, allows for higher axial range at which the unambiguous phase imaging can be performed. The technique is capable of nanometer axial resolution. The noise level, which increases as a result of using two wavelengths, is then reduced to the level of a single wavelength. The method compares favorably to software unwrapping, as the technique does not produce non-existent phase steps. Curvature mismatch between the reference and object beams is numerically compensated. The 3D images of porous coal samples and SKOV-3 ovarian cancer cells are presented.
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The Concrete Holographic Image: an Examination of Spatial and Temporal Properties and their Application in a Religious Art WorkDawson, Paula Heatley, Art, College of Fine Arts, UNSW January 2000 (has links)
The premise of this thesis is that the ???concrete holographic image???, a laser transmission hologram which has an object or a hologram of an object as its subject, has unique spatial and temporal properties which can suggest a plurality of tenses to a viewer. There is a lack of comprehensive analysis of the holographic representational system within art related theoretical and critical writing and a tendency to analyse individual works only in terms of generalities which apply to the concepts surrounding the holographic medium. While these form an important background for art image production, in some cases corresponding to artists works, the existing written material on the subject is inadequate as a model from which to draw the all important temporal conclusions. To date the critical reception of holograms has made no mention of acuity, the size of the viewing frustum, the depth of the image and scant mention of interference phenomena which are the intrinsic factors which I believe precipitate temporal illusions. Therefore this thesis examines the concrete holographic image in great detail on its own terms, firstly through theories of the basic image forming phenomena of interference and diffraction and secondly through the techniques of production as they have been adapted for the making of my art works. The extent of the metaphorical and allegorical potential of the spatial and temporal properties of the concrete holographic image are put to the ultimate test in a commission for St Brigid???s Church, Coogee. The Shrine of the Sacred Heart commission for St Brigid???s requires a concrete holographic image to facilitate devotion to the Sacred Heart. The Sacred Heart is not a physical thing but a complex, evolving spiritual entity with a realist pictorial history.
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