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Schwiegerling, Jim. "Optical transfer function expansion of quadratic pupils." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/627185.
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Quadratic pupils representing Gaussian apodization and defocus are expanded into Zernike polynomials. Combinations of the pupil expansion coefficients are used, in turn to expand the Optical Transfer Function into a novel set of basis functions.
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Chang, Ken Kai-fu 1973. "Simulation of nonlinear optic-fibre communication systems using Volterra series transfer function techniques." Monash University, Dept. of Electrical and Computer Systems Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7758.
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Schwiegerling, Jim. "Linear decomposition of the optical transfer function for annular pupils." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/626490.
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A technique for decomposing the Optical Transfer Function (OTF) into a novel set of basis functions has been developed. The decomposition provides insight into the performance of optical systems containing both wavefront error and apodization, as well as the interactions between the various components of the pupil function. Previously, this technique has been applied to systems with circular pupils with both uniform illumination and Gaussian apodization. Here, systems with annular pupils are explored. In cases of annular pupil with simple defocus, analytic expressions for the OTF decomposition coefficients can be calculated. The annular case is not only applicable to optical systems with central obscurations, but the technique can be extended to systems with multiple ring structures. The ring structures can have constant area as is often found in zone plates and diffractive lenses or the rings can have arbitrary areas. Analytic expressions for the OTF decomposition coefficients again can be determined for ring structures with constant and quadratic phase variations. The OTF decomposition provides a general tool to analyze and compare a diverse set of optical systems.
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Fang, Yi-chin. "Performance evaluation of discrete IR optical system." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270211.
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Fink, Charles G. "A study of the brain's transfer function for edge perception /." Online version of thesis, 1987. http://hdl.handle.net/1850/11189.
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Díaz, José Antonio, and Virendra N. Mahajan. "Diffraction and geometrical optical transfer functions: calculation time comparison." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/626488.
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In a recent paper, we compared the diffraction and geometrical optical transfer functions (OTFs) of an optical imaging system, and showed that the GOTF approximates the DOTF within 10% when a primary aberration is about two waves or larger [Appl. Opt., 55, 3241-3250 (2016)]. In this paper, we determine and compare the times to calculate the DOTF by autocorrelation or digital autocorrelation of the pupil function, and by a Fourier transform (FT) of the point-spread function (PSF); and the GOTF by a FT of the geometrical PSF and its approximation, the spot diagram. Our starting point for calculating the DOTF is the wave aberrations of the system in its pupil plane, and the ray aberrations in the image plane for the GOTF. The numerical results for primary aberrations and a typical imaging system show that the direct integrations are slow, but the calculation of the DOTF by a FT of the PSF is generally faster than the GOTF calculation by a FT of the spot diagram.
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Wang, Shu-i. 1964. "Three-dimensional incoherent optical transfer function in the presence of third-order spherical aberration." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276968.
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We derive the expression for the three-dimensional incoherent optical transfer function when third-order spherical aberration is present. The normalized version of the transfer function is numerically calculated for various amounts of spherical aberration. We find the effects of the aberration to be highly dependent on the spatial frequency in the longitudinal direction. We also calculate a structure content parameter, as a quality criterion, from the normalized transfer function. Remarkably, the structure content parameter dependence on spherical aberration is well-fit by a simple Cauchy curve for aberrations out to two waves at the margin.
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Lee, Yim Kul. "Nonlinear image processing and pattern analysis by rotating kernel transformation and optical fourier transform." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/14717.
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Levin, Marcy E. "The use of edge gradient analysis on chrome and emulsion photomasks to determine modulation transfer functions /." Online version of thesis, 1985. http://hdl.handle.net/1850/10148.
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Johnson, David C. "A shift variant filter applied to edge trace analysis /." Online version of thesis, 1989. http://hdl.handle.net/1850/11357.
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Choi, Junoh. "Optical Performance Test & Analysis of Intraocular Lenses." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195496.
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Cataract is a condition in the eye that if left untreated, could lead to blindness. One of the effective ways to treat cataract is the removal of the cataractous natural crystalline lens and implantation of an artificial lens called an intraocular lens(IOL). The designs of the IOLs have shown improvements over the years to further imitate natural human vision. A need for an objective testing and analysis tool for the latest IOLs grow with the advancements of the IOLs.In this dissertation, I present a system capable of objective test and analysis of the advanced IOLs. The system consists of-Model eye into which an IOL can be inserted to mimic conditions of the human eye.-Modulation Transfer Function measurement setup capable of through-focus test for depth of field studies and polychromatic test for study of effects of chromatization.-Use of Defocus Transfer Function to simulate depth of field characteristic of rotationally symmetric multifocal designs and extension of the function to polychromatic conditions.-Several target imaging experiments for comparison of stray light artifacts and simulation using a non-sequential ray trace package.
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Su, Tianquan. "Asphercial Metrology for Non-Specular Surfaces with the Scanning Long-Wave Optical Test System." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347221.
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Aspherical optics are increasingly used these days. The application of aspherical surfaces on large, astronomical telescope mirrors brings challenge to the fabrication. Since the surface radius of curvature varies across the surface, the grinding/polishing tool needs to change its shape when working on different parts of the surface, making surface error more easily embedded into the surface. Therefore, a tighter test-fab loop is needed to guide the fabrication process. To maximize the accuracy during the grinding of the surface and to minimize the working time in the polishing stage, a better metrology device that can measure rough surface is needed to guide the grinding process. Scanning long-wave optical test system (SLOTS) is designed to meet this demand by providing accurate, fast, large dynamic range, and high spatial resolution measurements on rough optical surfaces (surface rms roughness<1.7 µm).SLOTS is a slope measuring deflectometry system that works like a reversed wire test. It measures the reflection of the infrared light off the test surface, and calculates the local slope of the test surface. The surface sag/height is obtained through integration. During the test, a heated metal ribbon radiates long-wave infrared light that is reflected by the test surface. A thermal imaging camera records the reflected light. The ribbon is scanned in two orthogonal directions. From the variation of the irradiance recorded by the camera, slope maps of the test surface can be retrieved in the two orthogonal directions. SLOTS is a combination of tradition slope measurement and modern technology, processing advantages from both parts. It measures surface slope, so there is no need for null optics. It uses an uncooled thermal imaging camera that is made with high resolution and high sensitivity. The linear stage used to scan the hot ribbon has long travel, small resolution, and high accuracy. Both the camera and stage enable SLOTS a large dynamic range and high sensitivity. SLOTS has successfully guided the grinding process of the primary mirror of Daniel K. Inouye Solar Telescope. This mirror is a 4-meter diameter off-axis parabola (OAP). Its largest aspherical departure is 8 mm. SLOTS is able to measure it without any null optics. Under the guidance of SLOTS, the surface shape was controlled to be 1 µm rms within designed shape (with astigmatism removed) at 0.7 µm rms surface roughness (12 µm loose abrasive grits).
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Barbarini, Elisa Signoreto. "Análise óptica de sistemas eletro-ópticos por meio do cálculo da função de transferência de modulação." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18152/tde-20062012-151937/.
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Um grande número de equipamentos utilizam sistemas ópticos ou eletro-ópticos em suas estruturas, dentre esses equipamentos tem-se os microscópios, telescópios, equipamentos médicos, câmeras de satélites, entre outros. Com isso a necessidade de métodos e ferramentas que auxiliem na determinação do desempenho e da qualidade dos sistemas ópticos é crescente. Um dos métodos mais utilizados para realizar a análise de sistemas ópticos é a determinação da Função de Transferência de Modulação (Modulation Transfer Function - MTF). A MTF representa uma verificação quantitativa e direta da qualidade da imagem, e, além disso, é um teste objetivo que pode ser utilizado em sistemas ópticos concatenados. Esse trabalho apresenta a implementação de um software, denominado de SMTF (Software Modulation Transfer Function), para cálculo da MTF de equipamentos eletro-ópticos. O software foi utilizado para realizar o cálculo da MTF do Retinógrafo Digital, Imageador Termal e Microscópio Cirúrgico Oftalmológico. A informação da MTF auxilia na análise do alinhamento e medição da qualidade óptica, e também define o limite de resolução dos sistemas ópticos, por meio do gráfico da MTF. Os resultados obtidos, com o Retinógrafo e o Imageador Termal, foram comparados com os valores teóricos adquiridos pelo Zemax, que é um software utilizado para desenvolvimento e análise de lentes ou conjuntos ópticos. Já para o Microscópio os resultados obtidos da MTF foram comparados com os resultados obtidos pela MTF medida do Microscópio marca Zeiss, considerado como padrão de qualidade de Microscópios Oftalmológicos. Os resultados obtidos demonstram que o software apresentou ótimo desempenho permitindo uma análise direta e objetiva do comportamento de sistemas ópticos. Com auxílio do software foi feito o alinhamento do Retinógrafo Digital e do Imageador Termal e foi verificada a qualidade da imagem do Microscópio Cirúrgico Oftalmológico.A number of devices use optics or electro-optics in their structures, such as microscopes, telescopes, medical equipments, satellites cameras, among others. The need for methods and tools that assist in determining the performance and quality of optical systems is increasing. One of the methods most used to perform analysis of optical systems is to measure the Modulation Transfer Function (MTF). The MTF represents a direct and quantitative verification of the image quality, and moreover, it is an objective test that can be used in concatenated optical systems. This paper presents the implementation of software, called SMTF (Software Modulation Transfer Function), in order to calculate the MTF of electro-optical systems. The software was used for calculating the MTF of Digital Fundus Camera, Thermal Imager and Ophthalmologic Surgery Microscope. The information MTF aids the analysis of alignment and measurement of optical quality, and also defines the limit resolution of optical systems, from the graph of MTF. The results obtained with the Fundus Camera and de Thermal Imager were compared with the theorical values acquired by the Zemax, wich is a software used for analysis and development of optical assemblies or lenses. For the Microscope, the results were compared with MTF measured of Microscope Zeiss model, which is the quality standard of ophthalmological microscope. The results show that the software has a good performance by allowing a straightforward analysis of the behavior of optical systems. With the aid of the software was made to align the Fundus Camera and the Thermal Imager and the image quality of Surgical Microscope Ophthalmology was verified.
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Gnawali, Rudra. "Berreman Approach to Optical Propagation Through Anisotropic Metamaterials." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1541108034610795.
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Yang, Zhijun. "Incoherent Imaging in the Presence of Atmospheric Turbulence and Refractivity." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1500284170323378.
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Chow, B. S. "Design a Phase Plate to Extend the Depth of Field for an Inexpensive Microscope System to Have the Muti-focus Ability." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42557.
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We propose an optical technique, also called wave front coding, that can extend the depth of field optically by phase plate without the need of post digital image processing (PDIP). This technique can replace the present expensive mechanical scanning for achieving 3D information recording or to avoid keeping adjusting the structure of the objective. This phase plate can be fabricated by the emerging technology of laser
direct-write photoresist patterning and subsequent reactive ion etching on a germanium substrate. The niche of our innovation is the exempt of PDIP. The dependence on PDIP causes the conventional researches in this field to develop a deteriorating phase plate to deteriorate the images in different depth to be the same worse. The deteriorated images can thus be fixed digitally by a same inverse optical transfer function method. In contrast, we replace the deteriorating plate with an improving plate. This plate can
improve the defocus image in general. This freedom in limitation enables us to have a better imaging effect when designing the improvement plate. For example, in our design we do not need to worry about the null points existing in the inverse method since there is no inverse method for us at all.
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Malicki, Michal. "Electronic and optical properties of hybrid gold - organic dye systems." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31742.
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Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.Committee Chair: Marder, Seth; Committee Co-Chair: Perry, Joseph; Committee Member: Dickson, Robert; Committee Member: El-Sayed, Mostafa; Committee Member: Riedo, Elisa. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Slabá, Michala. "Teoretický popis zobrazení digitálním holografickým mikroskopem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229110.
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The diploma thesis deals with theory of imaging in a transmitted-light digital holographic microscope using partially coherent illumination. The influence of spatial and temporal coherence state on optical sectioning property is solved. The coherent transfer function is calculated. From this function imaging characteristics for a two-dimensional scattering object are derived depending on its defocus. Two different designs of microscopes developed in the Laboratory of optical microscopy in IPE FME BUT are considered.
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Nattinger, Kevin T. "Experimental Validation of the Generalized Harvey-Shack Surface Scatter Theory." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1536246922074747.
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Arnison, Matthew Raphael. "Phase control and measurement in digital microscopy." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/569.
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The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise.
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Arnison, Matthew Raphael. "Phase control and measurement in digital microscopy." University of Sydney. Physics, 2003. http://hdl.handle.net/2123/569.
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The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise.
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Vieira, Marcelo Andrade da Costa. "Metodologia baseada nas funções de transferência para pré-processamento de imagens mamográficas digitais e sua aplicação em esquema computacional de auxílio ao diagnóstico." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-19112007-144354/.
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Este trabalho tem por objetivo a investigação do comportamento de equipamentos de radiodiagnóstico em termos da qualidade da imagem produzida e a subseqüente aplicação desses resultados na otimização do desempenho de esquemas computacionais de auxílio ao diagnóstico, também conhecidos como esquemas CAD (do inglês, Computer-Aided Diagnosis). A principal meta consiste no desenvolvimento de técnicas de pré-processamento para imagens mamográficas digitalizadas que as realçasse de acordo com as características e limitações dos equipamentos utilizados na sua aquisição. A proposta está dividida em duas etapas. Na primeira, foram determinadas as características relativas tanto à resolução espacial como à resolução de contraste de diversos equipamentos mamográficos, avaliadas respectivamente pelas funções de transferência óptica e espectros de Wiener do ruído. Isto permitiu, numa segunda etapa, o desenvolvimento de um filtro digital específico para o pré-processamento de diferentes conjuntos de mamogramas digitais, separados de acordo com os equipamentos utilizados no processo de aquisição. Dessa forma, cada imagem mamográfica teve sua qualidade melhorada de acordo com as características do equipamento que a gerou, determinadas na primeira etapa. Essas imagens, depois de realçadas, foram utilizadas em um esquema CAD previamente desenvolvido, onde pôde ser observada uma melhora em até 12% no seu desempenho quando comparado aos resultados obtidos com imagens mamográficas não realçadas.The purpose of this work is to evaluate the quality of radiological equipment and their images in order to use these evaluations to improve the performance of a computer-aided diagnosis (CAD) scheme. The mean idea is about the development of image processing techniques to enhance digital mammograms according to the characteristics of the X-ray unit used for image acquisition. This work is basically divided in two parts. In the first one, it were determined the characteristics related to spatial and contrast resolution of several mammographic equipment, evaluated respectively from the optical transfer function and noise Wiener spectrum. This evaluation allowed, in a second part, the development of a preprocessing technique to enhance different set of digital mammographic images, gathered according to the equipment used on its acquisition process. Thus, each mammographic image had its quality improved in conformity with the characteristics of the equipment used on its acquisition, determined in the first part of this work. These images, after the enhancement process, were used on a previously developed CAD scheme. It was observed an improvement of 12% on the CAD performance using pre-processed mammograms compared to the results obtained when using non-enhanced mammographic images.
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Štolzová, Hana. "Analýza limitů zobrazování multimodovými optickými vlákny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-392838.
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Multimódová vlákna jsou zobrazovacím prostředkem s významným potenciálem v in-vivo mikroendoskopii. V poslední době tato metoda zaznamenala velký rozvoj, a to díky zdokonalování výpočetní a jiné techniky, například prostorové modulace světla. Cílem této práce bylo nalézt specifické limity zobrazování multimódovými vlákny a představit jejich počítačovou simulaci. Byl zkoumán vliv způsobu osvětlení optického systému obsahujícího multimódové vlákno na jeho schopnost fokusace a zobrazování. Analýzou dat získaných ze simulací a experimentu bylo zjištěno, že různá míra omezení Gaussovského svazku a plnění apertury multimódového vlákna má za následek významnou změnu zobrazovacích schopností systému. Při pozorování kvality fokusace bylo zjištěno, že nejlépe se projevují svazky málo omezené aperturou vlákna. Tento fakt byl potvrzen i experimentálním měřením. Zobrazování za použití svazků s podobnými hodnotami omezení (50%) projevovalo i nejlepší schopnost přenosu kontrastu. Avšak při analýze rozlišení dvou bodových objektů se jako nejvhodnější projevily svazky významně přeplňující numerickou aperturu vlákna, 100% a více. Přítomnost tohoto rozdílu poukazuje na skutečnost, že multimódové vlákno není zcela náhodné médium, ale propagace světla skrz multimódové vlákno projevuje znaky závislosti na vnějších zobrazovacích podmínkách, jako je například změna omezení osvětlovacího svazku. V této práci bylo představeno několik způsobů vyhodnocení kvality zobrazování pomocí multimódového vlákna. Každé z těchto kritérií podalo dílčí charakteristiku chování optického systému obsahujícího multimódové optické vlákno. Jednotlivé výsledky se neshodují na jednom konkrétním řešení a nutí osobu využívající zobrazovací systém obsahující multimódové vlákno ke zvážení několika aspektů, a to v jakém prostředí bude daný optický systém využívat a který parametr kvality zobrazení bude považovat za nejdůležitější.
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Schiabel, Homero. "Proposta de simulação computacional para avaliação de sistemas de imagem radiológica pelo método das funções de transferência." Universidade de São Paulo, 1992. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-19032009-094632/.
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A presente tese demonstra, a partir da avaliação convencional pelo método das Funções de Transferência de sistemas de imagem radiológica, que é necessário obter imagens de fenda em diversas orientações no campo para que essa análise tenha um significado mais real no caso de sistemas não isotrópicos. Isso provém da não linearidade na variação entre as FTMs obtidas para diversas direções 0 e 90°C relativas ao eixo do tubo de raios-X. Essa verificação, entretanto, representa um sério problema prático, pois indica um aumento no grau de complexidade de um método que, embora considerado o mais preciso pela maioria dos pesquisadores, tem sido utilizado apenas por laboratórios muito bem equipados. Assim, visando solucionar esse problema, esta tese propõe um novo método de simulação por computador que calcula a FEL e a FTM devidas ao ponto focal, dispensando, portanto, todo o complexo aparato experimental convencionalmente utilizado, o que contribui para tornar acessível à avaliação pelas funções de transferência a qualquer unidade radiológica. Por fim, faz parte desse trabalho também uma investigação do significado físico das variações registradas entre as FTMs e um estudo formal desenvolvido acerca dos conceitos da característica de campo e da magnificação lateral.From the conventional evaluation by the radiological systems Transfer Functions, this work shows that it is necessary to obtain slit images at several field orientations so that this annalysis has a more real significance for non-isotropic systems. This is achieved from the non-linearity on the variations among the MTFs obtained in several directions between 0 and 90°C relative to the X-ray tube axis. This notification, however, represents a serious practical matter, because it shows an increase on the complexity of a method which has been used just by well structured laboratories, although many researchers have considered it the most accurate. Hence, in order to solve this problem, we present a new computer simulation method which calculates the LSF and the MTF due to the focal spot, without all the conventional complex experimental apparatus. This makes the evaluation by the transfer functions suitable to any radiological unit. Finally, it is also part of this work an investigation of the physical meaning of the variations among the MTFs and a formal study about the field characteristics and the lateral magnification concepts.
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Raj, Kannan. "Investigations of three-dimensional optical transfer functions." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03142009-040539/.
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Sarafraz, Yazdi Hossein. "Fractional Fourier transform and its optical applications." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/992.
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A definition of fractional Fourier transform as the generalization of ordinary Fourier transform is given at the beginning. Then due to optical reasons the fractional transform of a so-called chirp functions is considered in both theory and practical simulations. Because of a quadratic phase factor which is common in the definition of the transform and some optical concepts, a comparison between these concepts such as Fresnel diffraction, spherical wave, thin lens and free space propagation and the transform has been done. Finally an optical setup for performing the fractional transform is introduced.
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Kuprenaite, Sabina. "Heterogeneous integration of functional thin films for acoustic and optical devices." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD039.
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Le contrôle de la microstructure et de la morphologie de surface est essentiel pour que les couches minces soient appliquées dans des dispositifs optiques et acoustiques. Des couches minces de TiO2, LaNiO3 et ZnO et leurs hétérostructures ont été obtenues par des techniques de pulvérisation cathodique à radio fréquence et de dépôt chimique en phase vapeur (CVD). L'optimisation des paramètres de dépôt, tels que la température, la pression totale de la chambre, la pression partielle d'O2 et la vitesse de croissance, a conduit à une amélioration de la qualité structurelle et fonctionnels des films minces et de leurs hétérostructures. L'orientation des couches minces épitaxiales de ZnO et TiO2 a été ajustée non seulement par le lien épitaxial avec divers substrats, mais également par les conditions de dépôt. La qualité optique des films de TiO2 a été principalement optimisée par l'élimination des défauts de microstructure et l'augmentation de la non-stoechiométrie en oxygène. Il a été démontré que les défauts ponctuels et microstructuraux dans les films polycristallins et épitaxiaux jouent un rôle clé dans les pertes de propagation optique. L'effet de la polarité du substrat sur les propriétés structurelles, optiques et acoustiques des films minces à base de ZnO a également été étudié. Les couches sacrificielles et / ou d'initiation de croissance ont été identifiées pour l'intégration hétérogène de films acoustiques et optiques fonctionnels sur substrats semi-conducteursThe control of microstructure and surface morphology is essential for the thin films to be applied in optical and acoustic devices. Thin films of TiO2, LaNiO3 and ZnO and their heterostructures in this work were obtained by radio frequency (RF) magnetron sputtering and metalorganic chemical vapor deposition (MOCVD) techniques. The optimization of deposition parameters, such as temperature, total chamber pressure, O2 partial pressure and growth rate, led to high structural quality of functional thin films and their heterostructures. The orientation of epitaxial ZnO and TiO2 thin films was tuned not only through lattice matching with various substrates, but as well through deposition conditions. The optical quality of TiO2 films was mostly optimized through elimination of microstructural defects and increasing oxygen non-stoichiometry. It was shown that microstructural and lattice defects in polycrystalline and epitaxial films played a key role in optical propagation losses. Effect of substrate polarity on the structural, optical and acoustic properties of ZnO-based thin films was studied, as well. The sacrificial and/or seed layers were identified for heterogeneous intégration of functional acoustical and optical films with semiconductor substrates
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Mustonen, Juvi K. "Spatial contrast sensitivity and external noise: applications to optical and neural modulation transfer functions." Thesis, Aston University, 1995. http://publications.aston.ac.uk/14551/.
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The thesis will show how to equalise the effect of quantal noise across spatial frequencies by keeping the retinal flux (If-2) constant. In addition, quantal noise is used to study the effect of grating area and spatial frequency on contrast sensitivity resulting in the extension of the new contrast detection model describing the human contrast detection system as a simple image processor. According to the model the human contrast detection system comprises low-pass filtering due to ocular optics, addition of light dependent noise at the event of quantal absorption, high-pass filtering due to the neural visual pathways, addition of internal neural noise, after which detection takes place by a local matched filter, whose sampling efficiency decreases as grating area is increased. Furthermore, this work will demonstrate how to extract both the optical and neural modulation transfer functions of the human eye. The neural transfer function is found to be proportional to spatial frequency up to the local cut-off frequency at eccentricities of 0 - 37 deg across the visual field. The optical transfer function of the human eye is proposed to be more affected by the Stiles-Crawford -effect than generally assumed in the literature. Similarly, this work questions the prevailing ideas about the factors limiting peripheral vision by showing that peripheral optical acts as a low-pass filter in normal viewing conditions, and therefore the effect of peripheral optics is worse than generally assumed.
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Dunn, Derrek Butler. "Real-Time Image Processing Using Acousto-Optic Bragg Diffraction." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30563.
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Optical image processing systems using an acousto-optic cell have been studied previously. However, these previous studies have been limited to two diffracted order in the Bragg regime and two spatial dimensions. Some comparisons between experimental data and theoretical predictions have been made. This dissertation studies image processing by acousto-optic Bragg diffraction to perform image enhanment. Theoretical results involving two diffracted orders in three spatial dimensions is presented. Experimental data is presented that confirms the validity of the theoretical results. Detailed analysis of several optical image processing system using acousto-optic modulators is presented. Also, the methodology use to derive an analytically expression in three spatial dimension for the interaction of an arbitrary light profile and a rectangular sound column in an acousto-optic cell is presented. Lastly, the ability to change the characteristics of the derived transfer function that mathematically represents the interaction of light and sound inside the acousto-optic cell is discussed and future research topics is given.Ph. D.
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Lošťák, Martin. "Koherencí řízená holografická mikroskopie v opticky rozptylujících prostředích." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234254.
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This thesis deals with imaging through diffuse media in coherence-controlled holographic microscope (CCHM) developed in IPE FME BUT. The mutual coherence function as well as the signal dependence on the lateral mutual shift between both arms of the CCHM are calculated. Both functions are related to each other. The latter dependence is measured experimentally. A principle of imaging with CCHM through diffuse media with both ballistic and diffuse light is explained by a simple geometrical model. This model is then verified experimentally by imaging a sample through diffuse medium. The point spread function (PSF) of CCHM for imaging through diffuse media is then calculated. Results of PSF calculation are proved experimentally.
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Nabolsi, Hawraa. "Contrôle optimal des équations d'évolution et ses applications." Thesis, Valenciennes, 2018. http://www.theses.fr/2018VALE0027/document.
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Dans cette thèse, tout d’abord, nous faisons l’Analyse Mathématique du modèle exact du chauffage radiatif d’un corps semi-transparent $\Omega$ par une source radiative noire qui l’entoure. Il s’agit donc d’étudier le couplage d’un système d’Equations de Transfert Radiatif avec condition au bord de réflectivité indépendantes avec une équation de conduction de la chaleur non linéaire avec condition limite non linéaire de type Robin. Nous prouvons l’existence et l’unicité de la solution et nous démontrons des bornes uniformes sur la solution et les intensités radiatives dans chaque bande de longueurs d’ondes pour laquelle le corps est semi-transparent, en fonction de bornes sur les données, Deuxièmement, nous considérons le problème du contrôle optimal de la température absolue à l’intérieur du corps semi-transparent $\Omega$ en agissant sur la température absolue de la source radiative noire qui l’entoure. À cet égard, nous introduisons la fonctionnelle coût appropriée et l’ensemble des contrôles admissibles $T_{S}$, pour lesquels nous prouvons l’existence de contrôles optimaux. En introduisant l’espace des états et l’équation d’état, une condition nécessaire de premier ordre pour qu’un contrôle $T_{S}$ : t ! $T_{S}$ (t) soit optimal, est alors dérivée sous la forme d’une inéquation variationnelle en utilisant le théorème des fonctions implicites et le problème adjoint. Ensuite, nous considérons le problème de l’existence et de l’unicité d’une solution faible des équations de la thermoviscoélasticité dans une formulation mixte de type Hellinger- Reissner, la nouveauté par rapport au travail de M.E. Rognes et R. Winther (M3AS, 2010) étant ici l’apparition de la viscosité dans certains coefficients de l’équation constitutive, viscosité qui dépend dans ce contexte de la température absolue T(x, t) et donc en particulier du temps t. Enfin, nous considérons dans ce cadre le problème du contrôle optimal de la déformation du corps semi-transparent $\Omega$, en agissant sur la température absolue de la source radiative noire qui l’entoure. Nous prouvons l’existence d’un contrôle optimal et nous calculons la dérivée Fréchet de la fonctionnelle coût réduiteThis thesis begins with a rigorous mathematical analysis of the radiative heating of a semi-transparent body made of glass, by a black radiative source surrounding it. This requires the study of the coupling between quasi-steady radiative transfer boundary value problems with nonhomogeneous reflectivity boundary conditions (one for each wavelength band in the semi-transparent electromagnetic spectrum of the glass) and a nonlinear heat conduction evolution equation with a nonlinear Robin boundary condition which takes into account those wavelengths for which the glass behaves like an opaque body. We prove existence and uniqueness of the solution, and give also uniform bounds on the solution i.e. on the absolute temperature distribution inside the body and on the radiative intensities. Now, we consider the temperature $T_{S}$ of the black radiative source S surrounding the semi-transparent body $\Omega$ as the control variable. We adjust the absolute temperature distribution (x, t) 7! T(x, t) inside the semi-transparent body near a desired temperature distribution Td(·, ·) during the time interval of radiative heating ]0, tf [ by acting on $T_{S}$. In this respect, we introduce the appropriate cost functional and the set of admissible controls $T_{S}$, for which we prove the existence of optimal controls. Introducing the State Space and the State Equation, a first order necessary condition for a control $T_{S}$ : t 7! $T_{S}$ (t) to be optimal is then derived in the form of a Variational Inequality by using the Implicit Function Theorem and the adjoint problem. We come now to the goal problem which is the deformation of the semi-transparent body $\Omega$ by heating it with a black radiative source surrounding it. We introduce a weak mixed formulation of this thermoviscoelasticity problem and study the existence and uniqueness of its solution, the novelty here with respect to the work of M.E. Rognes et R. Winther (M3AS, 2010) being the apparition of the viscosity in some of the coefficients of the constitutive equation, viscosity which depends on the absolute temperature T(x, t) and thus in particular on the time t. Finally, we state in this setting the related optimal control problem of the deformation of the semi-transparent body $\Omega$, by acting on the absolute temperature of the black radiative source surrounding it. We prove the existence of an optimal control and we compute the Fréchet derivative of the associated reduced cost functional
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Mohamed, Fathi Husain Alhadi. "Mitigation of Amplitude and Phase Distortion of Signals Under Modified Von Karman Turbulence Using Encrypted Chaos Waves." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1467943201.
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Castignoles, Fannie. "Conception, réalisation et évaluation d'un implant diffractif bifocal intracornéen pour la correction de la presbytie." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4036.
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Actuellement, la presbytie peut être corrigée chirurgicalement à l’aide d’implants intraoculaires réfractifs ou diffractifs multifocaux (chirurgie endoculaire invasive et irréversible) ou en intracornéen avec une correction multifocale réfractive (correction laser irréversible, ou insertion d’un implant dans le stroma). L’objectif de ce travail est de développer un nouvel implant permettant de corriger la presbytie, qui allie l’innocuité et la réversibilité d’une correction intracornéenne, à l’efficacité du diffractif. Le design des profils optiques bifocaux a été permis grâce au développement d’outils de simulation optique. Les efficacités de diffraction sont calculées à partir de la propagation du champ électrique par spectre angulaire. La qualité optique est déterminée d’après les simulations de Fonction de Transfert de Modulation obtenues sous Zemax. Des simulations de rendu d’images permettent de visualiser les effets de différents profils envisagés. Les paramètres critiques du design optique sont déterminés. Le choix du matériau dépend des contraintes de biocompatibilité de l’implant et des techniques de fabrication. La solution retenue est un hydrogel à forte teneur en eau, couplé à une nouvelle architecture de l’implant. L’hydrogel est obtenu par polymérisation radicalaire de macromonomères difonctionnels de poly(éthylène glycol) de masses molaires de l’ordre de 8000 g.mol‐1 qui conduisent à des propriétés mécaniques et une perméabilité aux nutriments compatibles avec l’application. La réalisation, la stérilisation et la caractérisation optique de prototypes ont abouti à la preuve du concept d’un implant bifocal diffractif intracornéenPresbyopia can be corrected with surgery by means of refractive or diffractive multifocal intraocular lenses (which imply an irreversible and invasive endocular surgery) or by intracorneal multifocal refractive correction (irreversible laser correction, or insertion of an intrastromal implant). This work aims at developing a new implant to correct presbyopia, which takes advantage of both the harmlessness and the reversibility of an intracorneal correction, and the efficiency of diffractive optics. The design of the bifocal optical profiles was based on the development of optical simulation tools. The diffractive efficiencies are calculated from the distribution of the electric field with the method of angular spectrum. The optical quality is determined according to the simulations of Modulation Transfer Function obtained with Zemax. Images simulations show the effects of the different profiles studied. The critical parameters of the optical design are also determined. The choice of the material depends on several constraints such as biocompatibility and techniques of manufacturing. The adopted solution relies on the used of an hydrogel with high water content and the design of a new implant architecture. The hydrogel is obtained by radical polymerization of difunctional macromonomers of poly(ethylene glycol) with molar masses around 8000 g.mol‐1, allowing mechanical properties and permeability to nutriments compatible with the application. The realization, the sterilization and the characterization of prototypes showed the proof of the concept of a diffractive bifocal intracorneal implant
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Perez, Denise. "Light-Use Efficiency of Coral-Reef Communities: A Sensitivity Analysis Using an Optically Based Model of Reef Productivity and Calcification." NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/99.
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Biogeochemical processes of reefs have been studied for over fifty years, however, information is still lacking on several fundamental reef processes. This lack of information has been limited essentially by techniques that cannot repeatedly sample large spatial areas. These limitations can be reduced with the use of an optical model to estimate biogeochemical processes. This project applied Monteith's light-use efficiency model to coral reef communities for determining photosynthetic and calcification efficiency of light. Gross primary production and net calcification were pooled from the peer-reviewed literature to calculate efficiency. Process efficiency was then compared across functional types of reef communities (i.e., coral, algae/seagrasses, mixed, and sand), and by year, location, season, and depth. Photosynthetic efficiency was calculated from 19 studies, showing an average of 0.039 mol O2 mol-1 photons. Photosynthetic efficiency differed significantly for mixed communities between studies, and for algae/seagrass communities among depths. Calcification efficiency averaged at 0.007 mol CaCO3 mol-1 photons. Significant differences were found in calcification efficiency of algae/seagrasses and mixed reef communities among studies and localities. Additionally, calcification efficiency of algae/seagrasses varied significantly in accordance with depth. Future use of the light-use efficiency model will require determining the efficiency of each functional type to estimate gross production and calcification. Additionally, further investigation of the light-use efficiency model will require long-term measurements of APAR, which is the fraction of incident light absorbed, and the incorporation of environmental parameters that reduce efficiency.
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Imran, Hafiz Ali. "Remote Sensing Tools for Monitoring Grassland Plant Leaf Traits and Biodiversity." Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/329592.
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Grasslands are one of the most important ecosystems on Earth, covering approximately one-third of the Earth’s surface. Grassland biodiversity is important as many services provided by such ecosystems are crucial for the human economy and well-being. Given the importance of grasslands ecosystems, in recent years research has been carried out on the potential to monitor them with novel remote sensing techniques. Improved detectors technology and novel sensors providing fine-scale hyperspectral imagery have been enabling new methods to monitor plant traits (PTs) and biodiversity.
The aims of the work were to study different approaches to monitor key grassland PTs such as Leaf Area Index (LAI) and biodiversity-related traits. The thesis consists of 3 parts: 1) Evaluating the performance of remote sensing methods to estimate LAI in grassland ecosystems, 2) Estimating plant biodiversity by using the optical diversity approach in grassland ecosystems, and 3) Investigating the relationship between PTs variability with alpha and beta diversity for the applicability of the optical diversity approach in a subalpine grassland of the Italian Alps
To evaluate the performance of remote sensing methods to estimate LAI, temporal and spatial observations of hyperspectral reflectance and LAI were analyzed at a grassland site in Monte Bondone, Italy (IT-MBo). In 2018, ground temporal observations of hyperspectral reflectance and LAI were carried out at a grassland site in Neustift, Austria (AT-NEU). To estimate biodiversity, in 2018 and 2019 a floristics survey was conducted to determine species composition and hyperspectral data were acquired at two grassland sites: IT-MBo and University of Padova’s Experimental Farm, Legnaro, Padua, Italy (IT-PD) respectively. Furthermore, in 2018, biochemistry analysis of the biomass samples collected from the grassland site IT-MBo was carried out to determine the foliar biochemical PTs variability.
The results of the thesis demonstrated that the grassland spectral response across different spectral regions (Visible: VIS, red-edge: RE, Near-infrared: NIR) showed to be both site-specific and scale-dependent. In the first part of the thesis, the performance of spectral vegetation indices (SVIs) based on visible, red-edge (RE), and NIR bands alongside SVIs solely based or NIR-shoulder bands (wavelengths 750 - 900 nm) was evaluated. A strong correlation (R2 > 0.8) was observed between grassland LAI and both RE and NIR-shoulder SVIs on a temporal basis, but not on a spatial basis. Using the PROSAIL Radiative Transfer Model (RTM), it was demonstrated that grassland structural heterogeneity strongly affects the ability to retrieve LAI, with high uncertainties due to structural and biochemical PTs co-variation.
In the second part, the applicability of the spectral variability hypothesis (SVH) was questioned and highlighted the challenges to use high-resolution hyperspectral images to estimate biodiversity in complex grassland ecosystems. It was reported that the relationship between biodiversity (Shannon, Richness, Simpson, and Evenness) and optical diversity metrics (Coefficient of variation (CV) and Standard deviation (SD)) is not consistent across plant communities. The results of the second part suggested that biodiversity in terms of species richness could be estimated by optical diversity metrics with an R2 = 0.4 at the IT-PD site where the grassland plots were artificially established and are showing a lower structure and complexity from the natural grassland plant communities. On the other hand, in the natural ecosystems at IT-MBo, it was more difficult to estimate biodiversity indices, probably due to structural and biochemical PTs co-variation. The effects of canopy non-vegetative elements (flowers and dead material), shadow pixels, and overexposed pixels on the relationship between optical diversity metrics and biodiversity indices were highlighted.
In the third part, we examined the relationship between PTs variability (at both local and community scales, measured by standard deviation and by the Euclidean distances of the biochemical and biophysical PTs respectively) and taxonomic diversity (both α-diversity and β-diversity, measured by Shannon’s index and by Jaccard dissimilarity index of the species, families, and functional groups percent cover respectively) in Monte Bondone, Trentino province, Italy. The results of the study showed that the PTs variability metrics at alpha scale were not correlated with α-diversity. However, the results at the community scale (β-diversity) showed that some of the investigated biochemical and biophysical PTs variations metrics were associated with β-diversity. The SVH approach was also tested to estimate β-diversity and we found that spectral diversity calculated by spectral angular mapper (SAM) showed to be a better proxy of biodiversity in the same ecosystem where the spectral diversity failed to estimate alpha diversity, this leading to the conclusion that the link between functional and species diversity may be an indicator of the applicability of optical sampling methods to estimate biodiversity.
The findings of the thesis highlighted that grassland structural heterogeneity strongly affects the ability to retrieve both LAI and biodiversity, with high uncertainties due to structural and biochemical PTs co-variation at complex grassland ecosystems. In this context, the uncertainties of satellite-based products (e.g., LAI) in monitoring grassland canopies characterized by either spatially or temporally varying structure need to be carefully taken into account. The results of the study highlighted that the poor performance of optical diversity proxies in estimating biodiversity in structurally heterogeneous grasslands might be due to the complex relationships between functional diversity and biodiversity, rather than the impossibility to detect functional diversity with spectral proxies.
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XU, ZHI-SHAN, and 徐芝珊. "The theory and application of optical transfer function." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/25226003915909542335.
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Chang, Hao-Peng, and 張鎬鵬. "The Modulation Transfer Function Theory of Optical Imaging Systems." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/10793689464381058046.
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碩士國立成功大學
機械工程學系碩博士班
93
The purpose of this paper is to analysis the relationship of object light, optical system and image by Fourier optical.We will discuss the produce of Modulation Transfer Function, and derive MTFmathematic model and its physical meaning. MTF is an important norm of optical system efficiency. In this paper, we will explain MTF test patterns and the meaning of MTF graph, and use several mathematic theorems to describe rays' advance and the diffraction condition after rays through optical system. In different conditions, measurement and count of MTF are different;we will discuss that in this paper, too. In this paper, we will use pupil function to explain how MTF produce is and its count methods, we also use ray tracing to trace rays of optical system and get the spot diagram of image plane. We will use spot diagram to count line spread function, then we can get the MTF of optical system.
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Cheng, Chu-Ming, and 鄭竹明. "Optical transfer function and its applications to imaging and non-imaging optical systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/75646996750465435756.
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博士國立交通大學
光電工程學系
98
Today’s optical instruments and electro-optical consumer products demand high imaging quality, optical efficiency and high resolution with the volume of the machine, nevertheless, being compact. At the same time, extending the depth of focus (EDOF) in an imaging system has been a long-standing issue in optical designs. This thesis develop either an analytical or a semi-analytical model by the use of optical transfer function (OTF) and illumination formations on the study of imaging and non-imaging qualities in the incoherent imaging system. Since the illumination light could vary the intensity distribution of the reflective light from an object, we could no longer assume the OTF of the object equal to unity in an imaging system. Hence, we make the in-depth investigation into the relationship between OTF and the illumination light distribution by calculating the OTF using the pupil function with the amplitude transmittance function which is the term given to the characteristic of a non-imaging system, and the wave aberration function which is the term given to the characteristic of an imaging system. One of main contributions of this thesis is to implement and demonstrate the effective factor of the non-imaging system (i.e., illumination light) in OTF calculation for assessing and specifying the performance of an imaging system. Then, a new approach for EDOF in an incoherent imaging system has been demonstrated. It provides a programmable shaped pupil using structured light which is generated by a non-imaging system with a spatial light modulator such as the digital micromirror device (DMD) or the light-emitting-diode (LED)-array module. The semi-analytical results using the OTF indicate that the limiting resolution of an imaging system with a specific defocus coefficient, and the specific coefficients for spherical aberration and coma aberration can be improved significantly with a binary shaped pupil. The proposed structured light on aperture stop from the non-imaging system can offer a dynamically programmable approach for aberration compensation in an incoherent imaging system. Our proposed research provides the connection between non-imaging and imaging systems for extending the depth of focus and further enhancing the image quality in the conventionally incoherent imaging systems for light pipe, camera, microscope and projector with embedded illumination modulator.
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Wu, Jhong-yang, and 吳仲洋. "A Study of Signal Model Building for Optical Transfer Function." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/xnytd4.
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碩士國立中山大學
電機工程學系研究所
96
Kalman filter addresses an estimation problem defined by two models: the signal model and the observation model. In this thesis, the signal model is obtained from a ratio of the defected and clean pictures in frequency domain. The observation model is built for an additive measurement noise from electronic sampling. The statistics of the generating noise for the signal model is important in Kalman filtering. The focus of this thesis is to derive the variance of the generating noise in the middle band for the signal model. By this derived variance, the Kalman filter is thus possible to be applied to estimate the optical transfer function for a defected imaging system in the future.
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Lee, Dick, and 李迪君. "The Analysis of Optical Transfer Function for an Infrared System with Array Sensors." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/76193264145777068331.
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Wang, Chenxi. "Investigation of Thin Cirrus Cloud Optical and Microphysical Properties on the Basis of Satellite Observations and Fast Radiative Transfer Models." Thesis, 2013. http://hdl.handle.net/1969.1/151213.
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This dissertation focuses on the global investigation of optically thin cirrus cloud optical thickness (tau) and microphysical properties, such as, effective particle size (D_(eff)) and ice crystal habits (shapes), based on the global satellite observations and fast radiative transfer models (RTMs). In the first part, we develop two computationally efficient RTMs simulating satellite observations under cloudy-sky conditions in the visible/shortwave infrared (VIS/SWIR) and thermal inferred (IR) spectral regions, respectively. To mitigate the computational burden associated with absorption, thermal emission and multiple scattering, we generate pre-computed lookup tables (LUTs) using two rigorous models, i.e., the line-by-line radiative transfer model (LBLRTM) and the discrete ordinates radiative transfer model (DISORT).
The second part introduces two methods (i.e., VIS/SWIR- and IR-based methods) to retrieve tau and D_(eff) from satellite observations in corresponding spectral regions of the two RTMs. We discuss the advantages and weakness of the two methods by estimating the impacts from different error sources on the retrievals through sensitivity studies.
Finally, we develop a new method to infer the scattering phase functions of optically thin cirrus clouds in a water vapor absorption channel (1.38-µm). We estimate the ice crystal habits and surface structures by comparing the inferred scattering phase functions and numerically simulated phase functions calculated using idealized habits.
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Derpich, Milan. "Optimal source coding with signal transfer function constraints." Thesis, 2009. http://hdl.handle.net/1959.13/34249.
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Research Doctorate - Doctor of Philosophy (PhD)This thesis presents results on optimal coding and decoding of discrete-time stochastic signals, in the sense of minimizing a distortion metric subject to a constraint on the bit-rate and on the signal transfer function from source to reconstruction. The first (preliminary) contribution of this thesis is the introduction of new distortion metric that extends the mean squared error (MSE) criterion. We give this extension the name Weighted-Correlation MSE (WCMSE), and use it as the distortion metric throughout the thesis. The WCMSE is a weighted sum of two components of the MSE: the variance of the error component uncorrelated to the source, on the one hand, and the remainder of the MSE, on the other. The WCMSE can take account of signal transfer function constraints by assigning a larger weight to deviations from a target signal transfer function than to source-uncorrelated distortion. Within this framework, the second contribution is the solution of a family of feedback quantizer design problems for wide sense stationary sources using an additive noise model for quantization errors. These associated problems consist of finding the frequency response of the filters deployed around a scalar quantizer that minimize the WCMSE for a fixed quantizer signal-to-(granular)-noise ratio (SNR). This general structure, which incorporates pre-, post-, and feedback filters, includes as special cases well known source coding schemes such as pulse coded modulation (PCM), Differential Pulse-Coded Modulation (DPCM), Sigma Delta converters, and noise-shaping coders. The optimal frequency response of each of the filters in this architecture is found for each possible subset of the remaining filters being given and fixed. These results are then applied to oversampled feedback quantization. In particular, it is shown that, within the linear model used, and for a fixed quantizer SNR, the MSE decays exponentially with oversampling ratio, provided optimal filters are used at each oversampling ratio. If a subtractively dithered quantizer is utilized, then the noise model is exact, and the SNR constraint can be directly related to the bit-rate if entropy coding is used, regardless of the number of quantization levels. On the other hand, in the case of fixed-rate quantization, the SNR is related to the number of quantization levels, and hence to the bit-rate, when overload errors are negligible. It is shown that, for sources with unbounded support, the latter condition is violated for sufficiently large oversampling ratios. By deriving an upper bound on the contribution of overload errors to the total WCMSE, a lower bound for the decay rate of the WCMSE as a function of the oversampling ratio is found for fixed-rate quantization of sources with finite or infinite support. The third main contribution of the thesis is the introduction of the rate-distortion function (RDF) when WCMSE is the distortion metric, denoted by WCMSE-RDF. We provide a complete characterization for Gaussian sources. The resulting WCMSE-RDF yields, as special cases, Shannon's RDF, as well as the recently introduced RDF for source-uncorrelated distortions (RDF-SUD). For cases where only source-uncorrelated distortion is allowed, the RDF-SUD is extended to include the possibility of linear-time invariant feedback between reconstructed signal and coder input. It is also shown that feedback quantization schemes can achieve a bit-rate only 0.254 bits/sample above this RDF by using the same filters that minimize the reconstruction MSE for a quantizer-SNR constraint. The fourth main contribution of this thesis is to provide a set of conditions under which knowledge of a realization of the RDF can be used directly to solve encoder-decoder design optimization problems. This result has direct implications in the design of subband coders with feedback, as well as in the design of encoder-decoder pairs for applications such as networked control. As the fifth main contribution of this thesis, the RDF-SUD is utilized to show that, for Gaussian sta-tionary sources with memory and MSE distortion criterion, an upper bound on the information-theoretic causal RDF can be obtained by means of an iterative numerical procedure, at all rates. This bound is tighter than 0:5 bits/sample. Moreover, if there exists a realization of the causal RDF in which the re-construction error is jointly stationary with the source, then the bound obtained coincides with the causal RDF. The iterative procedure proposed here to obtain Ritc(D) also yields a characterization of the filters in a scalar feedback quantizer having an operational rate that exceeds the bound by less than 0:254 bits/sample. This constitutes an upper bound on the optimal performance theoretically attainable by any causal source coder for stationary Gaussian sources under the MSE distortion criterion.
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Derpich, Milan. "Optimal source coding with signal transfer function constraints." 2009. http://hdl.handle.net/1959.13/34249.
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Research Doctorate - Doctor of Philosophy (PhD)This thesis presents results on optimal coding and decoding of discrete-time stochastic signals, in the sense of minimizing a distortion metric subject to a constraint on the bit-rate and on the signal transfer function from source to reconstruction. The first (preliminary) contribution of this thesis is the introduction of new distortion metric that extends the mean squared error (MSE) criterion. We give this extension the name Weighted-Correlation MSE (WCMSE), and use it as the distortion metric throughout the thesis. The WCMSE is a weighted sum of two components of the MSE: the variance of the error component uncorrelated to the source, on the one hand, and the remainder of the MSE, on the other. The WCMSE can take account of signal transfer function constraints by assigning a larger weight to deviations from a target signal transfer function than to source-uncorrelated distortion. Within this framework, the second contribution is the solution of a family of feedback quantizer design problems for wide sense stationary sources using an additive noise model for quantization errors. These associated problems consist of finding the frequency response of the filters deployed around a scalar quantizer that minimize the WCMSE for a fixed quantizer signal-to-(granular)-noise ratio (SNR). This general structure, which incorporates pre-, post-, and feedback filters, includes as special cases well known source coding schemes such as pulse coded modulation (PCM), Differential Pulse-Coded Modulation (DPCM), Sigma Delta converters, and noise-shaping coders. The optimal frequency response of each of the filters in this architecture is found for each possible subset of the remaining filters being given and fixed. These results are then applied to oversampled feedback quantization. In particular, it is shown that, within the linear model used, and for a fixed quantizer SNR, the MSE decays exponentially with oversampling ratio, provided optimal filters are used at each oversampling ratio. If a subtractively dithered quantizer is utilized, then the noise model is exact, and the SNR constraint can be directly related to the bit-rate if entropy coding is used, regardless of the number of quantization levels. On the other hand, in the case of fixed-rate quantization, the SNR is related to the number of quantization levels, and hence to the bit-rate, when overload errors are negligible. It is shown that, for sources with unbounded support, the latter condition is violated for sufficiently large oversampling ratios. By deriving an upper bound on the contribution of overload errors to the total WCMSE, a lower bound for the decay rate of the WCMSE as a function of the oversampling ratio is found for fixed-rate quantization of sources with finite or infinite support. The third main contribution of the thesis is the introduction of the rate-distortion function (RDF) when WCMSE is the distortion metric, denoted by WCMSE-RDF. We provide a complete characterization for Gaussian sources. The resulting WCMSE-RDF yields, as special cases, Shannon's RDF, as well as the recently introduced RDF for source-uncorrelated distortions (RDF-SUD). For cases where only source-uncorrelated distortion is allowed, the RDF-SUD is extended to include the possibility of linear-time invariant feedback between reconstructed signal and coder input. It is also shown that feedback quantization schemes can achieve a bit-rate only 0.254 bits/sample above this RDF by using the same filters that minimize the reconstruction MSE for a quantizer-SNR constraint. The fourth main contribution of this thesis is to provide a set of conditions under which knowledge of a realization of the RDF can be used directly to solve encoder-decoder design optimization problems. This result has direct implications in the design of subband coders with feedback, as well as in the design of encoder-decoder pairs for applications such as networked control. As the fifth main contribution of this thesis, the RDF-SUD is utilized to show that, for Gaussian sta-tionary sources with memory and MSE distortion criterion, an upper bound on the information-theoretic causal RDF can be obtained by means of an iterative numerical procedure, at all rates. This bound is tighter than 0:5 bits/sample. Moreover, if there exists a realization of the causal RDF in which the re-construction error is jointly stationary with the source, then the bound obtained coincides with the causal RDF. The iterative procedure proposed here to obtain Ritc(D) also yields a characterization of the filters in a scalar feedback quantizer having an operational rate that exceeds the bound by less than 0:254 bits/sample. This constitutes an upper bound on the optimal performance theoretically attainable by any causal source coder for stationary Gaussian sources under the MSE distortion criterion.
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Huang, Chien-Ta, and 黃建達. "The investigation of optimal personal peripheral to central blood pressure transfer function." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/72716021866023571807.
Full textAbstract:
碩士中原大學
生物醫學工程研究所
98
The central aortic pressure waveform contains the information about cardiac function and peripheral vascular system is an indicator for clinical evaluation of heart functions. Many of the physiological response mechanisms also affect the blood pressure and waveform, thus, so the central aortic blood pressure is frequently used as an important indicator of cardiovascular health. In clinical practice, invasive blood pressure measurement devices can provide continual blood pressure signal. Although these invasive devices are precise and accurate, they cannot be used in routine inspection. On the other hand, the non-invasive blood pressure measurement method can be applied in routine healthcare examination. However, most of these noninvasive devices can only provide the systole and diastole blood pressure readings. The purpose of this study is to construct peripheral vessel transfer function by frequency dependent transfer function and auto-regressive exogenous model (ARX model).The peripheral vascular model, is used to estimate the central aortic blood pressure waveform. This research can be divided into two parts: The first part is, to measure the brachial and radial artery pressure waveforms, using the non-invasive continuous blood pressure device, to construct peripheral transfer function by system identification method. The second part is to construct and valid the mathematical model of peripheral vascular transfer function using the aortic pressure waveform obtained by clinical devices. The result is extended to establish the relationship between peripheral and central aorta waveform. Furthermore, this study verifies the adjustment of peripheral vascular mathematical model to estimate the central aortic blood pressure. Finally, the optimal personal peripheral to central blood pressure transfer function is found. This study has successfully established a peripheral vascular model, and estimated the central aortic blood pressure using the optimal personal peripheral to central blood pressure transfer function. However, the optimal personal peripheral to central blood pressure transfer function is established using clinical carotid artery blood pressure waveform during evaluation. It is possible that there is a little difference between actual central aortic blood pressure and carotid artery blood pressure waveform. Nevertheless, in the future, it is possible to validate the result using invasive central aortic pressure waveform.
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Sailer, Markus Josef. "Simulationsrechnungen anisoplanatischer Übertragungsfunktionen für solare Adaptive Optik." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B60D-7.
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SYU, BO-SEN, and 許博森. "The Optimal Driving Analysis of Organic Light-Emitting Diode Lighting systems by Modeling System Transfer Functions." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/rt3spy.
Full textAbstract:
碩士國立臺北科技大學
光電工程系
107
This these research is to investigate the stability issues of driving the lighting system with multiple organic light-emitting diodes (OLED’s) under degradation by analyzing system transfer functions in which control-wise parameters were generated by simulation. A 2x2 OLED system in serial and parallel connections with and without feedbacks is used for modeling lighting system to evaluate their output gains under open and close-loop conditions. A 2x2 OLED system with independent active-matrix control and feedback is also applied to evaluate output gain under close-loop condition for comparison. The degradation of an OLED is modelled by increasing internal resistance. Our simulation result revealed that the output gain of the 2x2 system in serial and parallel connections increases about 20% as OLED degraded. Similar result is also shown in the 2x2 system with independent control.
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DiTanna, Anthony Santino. "The optimal control of a Lévy process." 2009. http://hdl.handle.net/2152/6652.
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In this thesis we study the optimal stochastic control problem of the drift of a Lévy process. We show that, for a broad class of Lévy processes, the partial integro-differential Hamilton-Jacobi-Bellman equation for the value function admits classical solutions and that control policies exist in feedback form. We then explore the class of Lévy processes that satisfy the requirements of the theorem, and find connections between the uniform integrability requirement and the notions of the score function and Fisher information from information theory. Finally we present three different numerical implementations of the control problem: a traditional dynamic programming approach, and two iterative approaches, one based on a finite difference scheme and the other on the Fourier transform.text
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Forbes, James Richard. "Design of Optimal Strictly Positive Real Controllers Using Numerical Optimization for the Control of Large Flexible Space Structures." Thesis, 2008. http://hdl.handle.net/1807/11142.
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The design of optimal strictly positive real (SPR) compensators using numerical optimization
is considered. The plants to be controlled are linear and nonlinear flexible manipulators.
For the design of SISO and MIMO linear SPR controllers, the optimization
objective function is defined by reformulating the H2-optimal control problem subject
to the constraint that the controllers must be SPR. Various controller parameterizations
using transfer functions/matrices and state-space equations are considered. Depending
on the controller form, constraints are enforced (i) using simple inequalities guaranteeing
SPRness, (ii) in the frequency domain, or (iii) by implementing the Kalman-Yakubovich-
Popov lemma. The design of a gain-scheduled SPR controller using numerical optimization
is also considered. Using a family of linear SPR controllers, the time dependent
scheduling signals are parameterized, and the objective function of the optimizer seeks
to find the form of the scheduling signals which minimizes the manipulator tip tracking
error while minimizing the control effort.
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Huang, Sheng-Chieh, and 黃聖捷. "Prediction on the phase transform, optical and dielectric properties of liquid crystal molecule system by coarse grained molecular dynamics simulation and density functional theory calculation." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3u4cw7.
Full textAbstract:
碩士國立中山大學
機械與機電工程學系研究所
102
We combine coarse grained (CG) molecular dynamics simulation and density functional theory (DFT) calculation to predict the phase behavior, the dielectric and the optical properties of liquid crystal molecule system. 4-Cyano-4′-pentylbiphenyl (5CB) is the earliest synthesized and the most popular liquid crystal molecule, which have prosperous related bibliographies and available experimental and theoretical data, so 5CB molecule is chosen to be the benchmark molecule. According to the Maier-Meier and Vuks equations, we have to obtain some parameters such as the dipole moment, the polarizability, the polarizability anisotropy, the order parameter and the molecular density to calculate dielectric and optical properties of liquid crystal molecule system. The CG model for the 5CB molecules is constructed, and the bond length, bending angle and nonbonded interaction parameters between CG beads, and then applied to the CGMD simulation to obtain the order parameter and molecular density. In addition, the polarizability and dipole moment of 5CB were obtained by DFT; therefore, the order parameter, the molecular density, the polarizability, and the dipole moment of 5CB were used to determine the dielectric constant, the dielectric anisotropy, refractive indices, and optical anisotropy by means of the Maier-Meier theory. Particularly, the calculation results from Maier-Meier theory can be improved by using effective dipole moment of the Dunmur-Palffy-Muhoray theory. Finally, our results show a good agreement with the experimental results, and it indicates that our simulation method is feasible and the results are accuracy.
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Buriánková, Eva. "Chování jednorozměrných integrálních operátorů na prostorech funkcí." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-346973.
Full textAbstract:
In this manuscript we study the action of one-dimensional integral operators on rearrangement-invariant Banach function spaces. Our principal goal is to characterize optimal target and optimal domain spaces corresponding to given spaces within the category of rearrangement-invariant Banach function spaces as well as to establish pointwise estimates of the non-increasing rearrangement of a given operator applied on a given function. We apply these general results to proving optimality relations between special rearrangement-invariant spaces. We pay special attention to the Laplace transform, which is a pivotal example of the operators in question. Powered by TCPDF (www.tcpdf.org)