Dissertations / Theses on the topic 'Optical data processing'
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1
Brand, Ulrich. "Optical data processing in high-NA imaging." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393167.
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R, S. Umesh. "Algorithms for processing polarization-rich optical imaging data." Thesis, Indian Institute of Science, 2004. https://etd.iisc.ac.in/handle/2005/96.
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This work mainly focuses on signal processing issues related to continuous-wave, polarization-based direct imaging schemes. Here, we present a mathematical framework to analyze the performance of the Polarization Difference Imaging (PDI) and Polarization Modulation Imaging (PMI). We have considered three visualization parameters, namely, the polarization intensity (PI), Degree of Linear Polarization (DOLP) and polarization orientation (PO) for comparing these schemes. The first two parameters appear frequently in literature, possibly under different names. The last parameter, polarization orientation, has been introduced and elaborated in this thesis. We have also proposed some extensions/alternatives for the existing imaging and processing schemes and analyzed their advantages.
Theoretically and through Monte-Carlo simulations, we have studied the performance of these schemes under white and coloured noise conditions, concluding that, in general, the PMI gives better estimates of all the parameters. Experimental results corroborate our theoretical arguments. PMI is shown to give asymptotically efficient estimates of these parameters, whereas PDI is shown to give biased estimates of the first two and is also shown to be incapable of estimating PO. Moreover, it is shown that PDI is a particular case of PMI. The property of PDI, that it can yield estimates at lower variances has been recognized as its major strength. We have also shown that the three visualization parameters can be fused to form a colour image, giving a holistic view of the scene. We report the advantages of analyzing chunks of data and bootstrapped data under various circumstances.
Experiments were conducted to image objects through calibrated scattering media and natural media like mist, with successful results. Scattering media prepared with polystyrene microspheres of diameters 2.97m, 0.06m and 0.13m dispersed in water were used in our experiments. An intensified charge coupled device (CCD) camera was used to capture the images. Results showed that imaging could be performed beyond optical thickness of 40, for particles with 0.13m diameter. For larger particles, the depth to which we could image was much lesser. An experiment using an incoherent source yielded better results than with coherent sources, which we attribute to the speckle noise induced by coherent sources. We have suggested a harmonic based imaging scheme, which can perhaps be used when we have a mixture of scattering particles. We have also briefly touched upon the possible post processing that can be performed on the obtained results, and as an example, shown segmentation based on a PO imaging result.This research was carried out with the support of Prof Hema Ramachandran of Raman Research Institute, Bangalore. Our thanks to her and RRI.
3
R, S. Umesh. "Algorithms for processing polarization-rich optical imaging data." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/96.
Full textAbstract:
This work mainly focuses on signal processing issues related to continuous-wave, polarization-based direct imaging schemes. Here, we present a mathematical framework to analyze the performance of the Polarization Difference Imaging (PDI) and Polarization Modulation Imaging (PMI). We have considered three visualization parameters, namely, the polarization intensity (PI), Degree of Linear Polarization (DOLP) and polarization orientation (PO) for comparing these schemes. The first two parameters appear frequently in literature, possibly under different names. The last parameter, polarization orientation, has been introduced and elaborated in this thesis. We have also proposed some extensions/alternatives for the existing imaging and processing schemes and analyzed their advantages.
Theoretically and through Monte-Carlo simulations, we have studied the performance of these schemes under white and coloured noise conditions, concluding that, in general, the PMI gives better estimates of all the parameters. Experimental results corroborate our theoretical arguments. PMI is shown to give asymptotically efficient estimates of these parameters, whereas PDI is shown to give biased estimates of the first two and is also shown to be incapable of estimating PO. Moreover, it is shown that PDI is a particular case of PMI. The property of PDI, that it can yield estimates at lower variances has been recognized as its major strength. We have also shown that the three visualization parameters can be fused to form a colour image, giving a holistic view of the scene. We report the advantages of analyzing chunks of data and bootstrapped data under various circumstances.
Experiments were conducted to image objects through calibrated scattering media and natural media like mist, with successful results. Scattering media prepared with polystyrene microspheres of diameters 2.97m, 0.06m and 0.13m dispersed in water were used in our experiments. An intensified charge coupled device (CCD) camera was used to capture the images. Results showed that imaging could be performed beyond optical thickness of 40, for particles with 0.13m diameter. For larger particles, the depth to which we could image was much lesser. An experiment using an incoherent source yielded better results than with coherent sources, which we attribute to the speckle noise induced by coherent sources. We have suggested a harmonic based imaging scheme, which can perhaps be used when we have a mixture of scattering particles. We have also briefly touched upon the possible post processing that can be performed on the obtained results, and as an example, shown segmentation based on a PO imaging result.
4
Fujinaga, Ichiro. "Optical music recognition using projections." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61870.
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TICKNOR, ANTHONY JAMES. "OPTICAL COMPUTING IN BOLTZMANN MACHINES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184169.
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This dissertation covers theoretical and experimental work on applying optical processing techniques ot the operation of a Boltzmann machine. A Boltzmann machine is a processor that solves a problem by iteratively optimizing an estimate of the solution. The optimization is done by finding a minimum of an energy surface over the solution space. The energy function is designed to consider not only data but also a priori information about the problem to assist the optimization. The dissertation first establishes a generic line-of-approach for designing an algorithmic optical computer that might successfully operate using currently realizable analog optical systems for highly-parallel operations. Simulated annealing, the algorithm of the Boltzmann machine, is then shown to be adaptable to this line-of-approach and is chosen as the algorithm to demonstrate these concepts throughout the dissertation. The algorithm is analyzed and optical systems are outlined that will perform the appropriate tasks within the algorithm. From this analysis and design, realizations of the optically-assisted Boltzmann machine are described and it is shown that the optical systems can be used in these algorithmic computations to produce solutions as precise as the single-pass operations of the analog optical systems. Further considerations are discussed for increasing the usefulness of the Boltzmann machine with respect to operating on larger data sets while maintaining the full degrees of parallelism and to increasing the speed by reducing the number of electronical-optical transducers and by utilizing more of the available parallelism. It is demonstgrated how, with a little digital support, the analog optical systems can be used to produce solutions with digital precision but without compromising the speed of the optical computations. Finally there is a short discussion as to how the Boltzmann machine may be modelled as a neuromorphic system for added insight into the computational functioning of the machine.
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Naulleau, Patrick. "Optical signal processing and real world applications /." Online version of thesis, 1993. http://hdl.handle.net/1850/12136.
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Svensson, Barbro Christina. "Nonlinear distributed couplers in zinc-sulfide waveguides." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184500.
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Nonlinear phenomena originating from the distributed coupling process were observed when distributed couplers, such as prisms and gratings, were used to couple light into nonlinear ZnS thin film waveguides. The efficiency of the nonlinear distributed coupling process was found to depend on two independent parameters, the angle of the incident beam and the power of the incident beam. Depending on the detuning of the incident angle, from the optimum incident angle at low powers, either optical limiting, power-dependent switching, or power-dependent bistability of the coupling efficiency, and thereby of the in-coupled power, was observed. At zero detuning, a twenty-fold decrease of the coupling efficiency with increasing powers was measured. At a nonzero detuning of the incident angle, power-dependent switching at milliwatt powers was observed. At larger angular detunings, corresponding to the angular width. FWHM, of the coupling peak at low powers, power-dependent bistability was observed, and the width of the bistability loop was found to increase with increasing detunings. All-optical beam scanning via a nonlinear grating coupler was also demonstrated, utilizing a control-signal beam configuration, where the signal beam scanned through an angle of 0.5° when the power of the control beam was varied. The observed nonlinearity in ZnS was positive and of thermal origin. The power-induced change in the refractive index was found to be 0.01 and a relaxation time of 10 μsec was measured. Problems with the long-term stability of the nonlinear distributed coupling process were traced to the occurrence of desorption and adsorption of water vapor in the ZnS films.
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Sitter, David Norbert. "Space invariant modeling in three-dimensional optical image formation." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/13450.
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Wang, Jade P. (Jade Peilynn) 1979. "Demonstrating effective all-optical processing in ultrafast data networks using semiconductor optical amplifiers." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44907.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
The demand for bandwidth in worldwide data networks continues to increase due to growing Internet use and high-bandwidth applications such as video. All-optical signal processing is one promising technique for providing the necessary capacity and offers payload transparency, power consumption which scales efficiently with increasing bit rates, reduced processing latency, and ultrafast performance. In this thesis, we focus on using semiconductor optical amplifier-based logic gates to address both routing and regeneration needs in ultrafast data networks. To address routing needs, we demonstrate a scalable, multi-packet all-optical header processing unit operating at a line rate of 40 Gb/s. For this experiment, we used the ultrafast nonlinear interferometer (UNI) gate, a discrete optical logic gate which has been demonstrated at speeds of 100 Gb/s for bit-wise switching. However, for all-optical switching to become a reality, integration is necessary to significantly reduce the cost of manufacturing, installation, and operation. One promising integrated all-optical logic gate is the semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI). This gate has previously been demonstrated capable of up to 80 Gb/s bit-wise switching operation. To enable simple installation and operation of this gate, we developed a performance optimization method which can quickly and accurately pinpoint the optimal operating point of the switch. This eliminates the need for a time-intensive search over a large parameter space and significantly simplifies the operation of the switch. With this method, we demonstrate the ability of a single SOA-MZI logic gate to regenerate ultrafast pulses over 100 passes and 10,000 km in a regenerative loop. Ultimately, all-optical logic gates must be integrated on a single low-cost platform and demonstrated in cascaded, multi-gate operation for increased functionality.
(cont.) This requires low-loss monolithic integration. Our approach to this involves an asymmetric twin waveguide (ATG) design. This design also has the potential for high-yields as a result of a high tolerance for fabrication errors. We present our characterization results of ATG waveguides and proposals for future improvements.
by Jade P. Wang.
Ph.D.
10
Subramaniam, Suresh. "All-optical networks with sparse wavelength conversion /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6032.
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Wu, Jikun, and 武继坤. "Gene fusion discovery through RNA-seq and inversion detection via optical mapping." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/195960.
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RNA-seq sequencing has revolutionized the landscape of whole transcriptome sequencing and analysis. With its capacity of sequencing in a high-throughput and low-cost way, it produced ever increasingly amount of RNA-seq reads that are mines of treasure in biological and therapeutic studies. However, due to the complex nature and relatively un-developed knowledge base of transcription process, many challenges exist in the modeling and investigation of RNA-seq read data. It is of high importance to develop efficient computational tools to satisfy these needs.
The first part of this thesis concentrates on algorithms for both upstream and downstream analysis of RNA-seq data. For the upstream, we aim to tackle down the problems of RNA-seq reads alignment where the segmental alignment causes the major difficulty. By employing a strategy of rigid extensive tries on read segmentations indices, we implemented an accurate algorithm for returning two-segmental alignments based on bi-directional BWT. For the downstream analysis, we study two types of gene fusion events which play a critical role in the formation of cancers. Unlike previous down-scoping-search methods, we applied a search-validate approach to design the framework. By introducing key techniques such as masking, two-segmental alignment and retention of multiple maps, we developed an efficient and robust tool for detecting gene fusions with high accuracy that proved by extensive simulation and real data tests.
Optical mapping is a cutting edge technique for the study of genomic structural variations which address the defect and limitation of paired-end sequencing. It was designed with great improvement in accuracy, resolution and throughput than current techniques. Also, it produces much longer molecules which enables us to explore genomic regions rich in repetitive sequences. Optical mapping has the potential to enable us to draw a complete picture of the genome structure polymorphism and it is important for us to design tools for analysis of the data.
The second part of the thesis is dedicated to the algorithms for both upstream and downstream analysis of optical map data. For the upstream, we formulated a robust scoring function, which combines the effectiveness of heuristic functions and the accuracy of statistical functions. Based on it, we implemented the high performance OMDP algorithm. For the downstream, we developed BP-OMDP which makes use of both split-mapping and disparity of coverage depth to call inversions in NA12878 human genome sample.published_or_final_version
Computer science
Doctoral
Doctor of Philosophy
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GonzaÌlez, Arcelus Isabel. "Advanced signal processing schemes for high density optical data storage." Thesis, University of Exeter, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413895.
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Xia, Bing 1972 Nov 7. "A direct temporal domain approach for ultrafast optical signal processing and its implementation using planar lightwave circuits /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103007.
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Ultrafast optical signal processing, which shares the same fundamental principles of electrical signal processing, can realize numerous important functionalities required in both academic research and industry. Due to the extremely fast processing speed, all-optical signal processing and pulse shaping have been widely used in ultrafast telecommunication networks, photonically-assisted RFlmicro-meter waveform generation, microscopy, biophotonics, and studies on transient and nonlinear properties of atoms and molecules. In this thesis, we investigate two types of optical spectrally-periodic (SP) filters that can be fabricated on planar lightwave circuits (PLC) to perform pulse repetition rate multiplication (PRRM) and arbitrary optical waveform generation (AOWG).First, we present a direct temporal domain approach for PRRM using SP filters. We show that the repetition rate of an input pulse train can be multiplied by a factor N using an optical filter with a free spectral range that does not need to be constrained to an integer multiple of N. Furthermore, the amplitude of each individual output pulse can be manipulated separately to form an arbitrary envelope at the output by optimizing the impulse response of the filter.
Next, we use lattice-form Mach-Zehnder interferometers (LF-MZI) to implement the temporal domain approach for PRRM. The simulation results show that PRRM with uniform profiles, binary-code profiles and triangular profiles can be achieved. Three silica based LF-MZIs are designed and fabricated, which incorporate multi-mode interference (MMI) couplers and phase shifters. The experimental results show that 40 GHz pulse trains with a uniform envelope pattern, a binary code pattern "1011" and a binary code pattern "1101" are generated from a 10 GHz input pulse train.
Finally, we investigate 2D ring resonator arrays (RRA) for ultraf ast optical signal processing. We design 2D RRAs to generate a pair of pulse trains with different binary-code patterns simultaneously from a single pulse train at a low repetition rate. We also design 2D RRAs for AOWG using the modified direct temporal domain approach. To demonstrate the approach, we provide numerical examples to illustrate the generation of two very different waveforms (square waveform and triangular waveform) from the same hyperbolic secant input pulse train. This powerful technique based on SP filters can be very useful for ultrafast optical signal processing and pulse shaping.
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Shen, Mengzhe, and 沈梦哲. "Parametric wavelength exchange and its application in high speed optical signal processing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841616.
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Shen, Mengzhe. "Parametric wavelength exchange and its application in high speed optical signal processing." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42841616.
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Apte, Madhav Vasudeo 1958. "Software modification and implementation for, and analysis of, lidar data." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276696.
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The software system to process integrated slant path lidar data has been debugged, modified, documented, and improved in reliability and user-friendliness. The substantial data set acquired since 1979 has been processed and a large body of results has been generated. A database has been implemented to store, organize, and access the results. The lidar data set results--the S ratios, the optical depths, and the mixing layer heights are presented. The seasonal dependence of the lidar solution parameters has been explored. The assumptions made in the lidar solution procedure are investigated. The sensitivity of the S ratio and the particulate extinction coefficient to the system calibration constant is examined. The reliability of the calibration constant is demonstrated by examining the particulate to Rayleigh extinction ratio values above the mixing layer.
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Peng, Qinmu. "Visual attention: saliency detection and gaze estimation." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/207.
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Visual attention is an important characteristic in the human vision system, which is capable of allocating the cognitive resources to the selected information. Many researchers are attracted to the study of this mechanism in the human vision system and have achieved a wide range of successful applications. Generally, there are two tasks encountered in the visual attention research including visual saliency detection and gaze estimation. The former is normally described as distinctiveness or prominence as a result of a visual stimulus. Given images or videos as input, saliency detection methods try to simulate the mechanism of human vision system, predicting and locating the salient parts in them. While the later involves physical device to track the eye movement and estimate the gaze points. As for saliency detection, it is an effective technique for studying and mimicking the mechanism of the human vision system. Most of saliency models can predict the visual saliency with the boundary or the rough location of the true salient object, but miss the appearance or shape information. Besides, they pay little attention to the image quality problem such as low-resolution or noises. To handle these problems, in this thesis, we propose to model the visual saliency from local and global perspectives for better detection of the visual saliency. The combination of the local and global saliency scheme employing different visual cues can make fully use of their respective advantages to compute the saliency. Compared with existing models, the proposed method can provide better saliency with more appearance and shape information, and can work well even in the low-resolution or noisy images. The experimental results demonstrate the superiority of the proposed algorithm. Next, video saliency detection is another issue for the visual saliency computation. Numerous works have been proposed to extract the video saliency for the tasks of object detection. However, one might not be able to obtain desirable saliency for inferring the region of foreground objects when the video presents low contrast or complicated background. Thus, this thesis develops a salient object detection approach with less demanding assumption, which gives higher detection performance. The method computes the visual saliency in each frame using a weighted multiple manifold ranking algorithm. It then computes motion cues to estimate the motion saliency and localization prior. By adopting a new energy function, the data term depends on the visual saliency and localization prior; and the smoothness term depends on the constraint in time and space. Compared to existing methods, our approach automatically segments the persistent foreground object while preserving the potential shape. We apply our method to challenging benchmark videos, and show competitive or better results than the existing counterparts. Additionally, to address the problem of gaze estimation, we present a low cost and efficient approach to obtain the gaze point. As opposed to eye gaze estimation techniques requiring specific hardware, e.g. infrared high-resolution camera and infrared light sources, as well as a cumbersome calibration process. We concentrate on visible-imaging and present an approach for gaze estimation using a web camera in a desktop environment. We combine intensity energy and edge strength to locate the iris center and utilize the piecewise eye corner detector to detect the eye corner. To compensate for head movement causing gaze error, we adopt a sinusoidal head model (SHM) to simulate the 3D head shape, and propose an adaptive weighted facial features embedded in the pose from the orthography and scaling with iterations algorithm (AWPOSIT), whereby the head pose can be estimated. Consequently, the gaze estimation is obtained by the integration of the eye vector and head movement information. The proposed method is not sensitive to the light conditions, and the experimental results show the efficacy of the proposed approach
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Chen, Yong. "Constructing a language model based on data mining techniques for a Chinese character recognition system /." View the Table of Contents & Abstract, 2004. http://sunzi.lib.hku.hk/hkuto/record/B30708527.
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Chen, Yong, and 陳勇. "Constructing a language model based on data mining techniques for a Chinese character recognition system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B44570193.
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Li, Xin. "Scheduling optical packet switches with reconfiguration delay /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?COMP%202005%20LI.
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Palani, Ananta. "Development of an optical system for dynamic evaluation of phase recovery algorithms." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708850.
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Wang, Xingle. "Event-driven dynamic power-on for Giga-bit very short reach optical transceivers." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.65 Mb., 83 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3221079.
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Foster, Michael S. "Using Lidar to geometrically-constrain signature spaces for physics-based target detection /." Online version of thesis, 2007. http://hdl.handle.net/1850/5827.
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Wear, Steven M. "Shift-invariant image reconstruction of speckle-degraded images using bispectrum estimation /." Online version of thesis, 1990. http://hdl.handle.net/1850/11219.
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Betts, Kevin Howard. "A microcomputer program for optical multilayer thin films." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25078.
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A microcomputer software package was written to calculate the tranmission and reflection characteristics of multilayer thin films on a substrate. The program was written to be as "user-friendly", versatile and modular as possible. To test the program, a transparent oxide-type heat-mirror film capped with an antireflection coating was studied for greenhouse applications. Si0₂ and ZnO were considered as representative antireflection and heat-mirror materials respectively. The results of calculations of heat transfer coefficient and transmittance of the glazing construction
polyethylene/air gap/Si0₂/ZnO/polyethylene are presented. The resulting structure is shown to give a visible light transmission spectrum which closely matches the plant sensitivity curve for plant growth and has higher thermal insulation compared to uncoated polyethylene.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Mokhtar, Ahmed. "Routing, switching, and multiaccess in all-optical networks /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5942.
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Fujinaga, Ichiro. "Adaptive optical music recognition." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42033.
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The basic goal of the Adaptive Optical Music Recognition system presented herein is to create an adaptive software for the recognition of musical notation. The focus of this research has been to create a robust framework upon which a practical optical music recognizer can be built.The strength of this system is its ability to learn new music symbols and handwritten notations. It also continually improves its accuracy in recognizing these objects by adjusting internal parameters. Given the wide range of music notation styles, these are essential characteristics of a music recognizer.
The implementation of the adaptive system is based on exemplar-based incremental learning, analogous to the idea of "learning by example," that identifies unknown objects by their similarity to one or more of the known stored examples. The entire process is based on two simple, yet powerful algorithms: k-nearest neighbour classifier and genetic algorithm. Using these algorithms, the system is designed to increase its accuracy over time as more data are processed.
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Collaer, Marcia Lee. "IMAGE DATA COMPRESSION: DIFFERENTIAL PULSE CODE MODULATION OF TOMOGRAPHIC PROJECTIONS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/291412.
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Gigioli, George William Jr. "Optimization and tolerancing of nonlinear Fabry Perot etalons for optical computing systems." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184537.
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Since the discovery of optical bistability a considerable amount of research activity has been aimed toward the realization of general-purpose all-optical computers. The basic premise for most of this work is the widely held notion that a reliable optical switch can be fabricated from a piece of optically bistable material. To date only a very small number of published articles have addressed the subject of the engineering issues (that is, the optimization and tolerancing) of these optical switches. This dissertation is a systematic treatment of these issues. From the starting point of Maxwell's equations a simple model of optically bistable Fabry-Perot etalons is outlined, in which the material is assumed to be a pure Kerr medium having linear absorption. This model allows for a relatively straightforward optical switch optimization procedure. The procedure is applicable for optimizing any number of switch parameters. The emphasis in this dissertation is on the optimization of the contrast of the switch's output signals, with the other parameters (switching energy, tolerance sensitivity) assuming a secondary yet critical role. Following the optimization of the optical switch is a tolerance analysis which addresses the manufacturability and noise immunity of the optimized switch. In the first part of this analysis equations describing the propagation of errors through a large scale system of like devices are derived from the truth tables of the switches themselves. From these equations worst case tolerances are established on the optical switch's transfer function parameters. In the second part of the tolerance analysis the bistability model is used to arrive at tolerances on the physical parameters of the switch. These tolerances are what determine the manufacturability of the optical switches. The major conclusion of the dissertation is that, within the range of validity of the model and the other simplifying assumptions, optically bistable Fabry-Perot etalons cannot be used reliably as logic gates in large-scale computing systems.
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Yu, Lingfeng. "Multidimensional data encryption with virtual optics /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20YU.
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Ozharar, Sarper. "Stable optical frequency comb generation and applications in arbitrary waveform generation, signal processing and optical data mining." Orlando, Fla. : University of Central Florida, 2008. http://purl.fcla.edu/fcla/etd/CFE0002388.
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Licona-Nunez, Jorge Estuardo. "M-ary Runlength Limited Coding and Signal Processing for Optical Data Storage." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5195.
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Recent attempts to increase the capacity of the compact disc (CD) and digital versatile disc (DVD) have explored the use of multilevel recording instead of binary recording. Systems
that achieve an increase in capacity of about three times that of conventional CD have been proposed for production. Marks in these systems are multilevel and fixed-length as opposed to binary and variable length in CD and DVD. The main objective of this work is to evaluate the performance of multilevel ($M$-ary) runlength-limited (RLL) coded sequences in optical data storage.
First, the waterfilling capacity of a multilevel optical recording channel ($M$-ary ORC) is derived and evaluated. This provides insight into
the achievable user bit densities, as well as a theoretical limit against which simulated systems can be compared.
Then, we evaluate the performance of RLL codes
on the $M$-ary ORC. A new channel model that includes the runlength constraint in the transmitted signal is used. We compare the performance of specific RLL codes, namely $M$-ary permutation codes, to that of real systems using multilevel fixed-length marks for recording and the theoretical limits. The Viterbi detector is used to estimate the original recorded symbols from the readout signal.
Then, error correction is used to reduce the symbol error probability. We use a combined ECC/RLL code for phrase encoding. We evaluate the use of trellis coded modulation (TCM) for amplitude encoding. The detection of the readout signal is also studied. A post-processing algorithm for the Viterbi detector is introduced,
which ensures that the detected word satisfies the code constraints. Specifying the codes and detector for the $M$-ary ORC gives a complete
system whose performance can be compared to that of the recently developed systems found in the literature and the theoretical limits calculated in this research.
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Jin, Ruxiang. "Nonlinear etalons and nonlinear waveguides as decision-making elements in photonic switching." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184807.
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This dissertation describes our recent results in the study of various types of photonic switches. Special attention is given to the devices with Fabry-Perot etalon or planar waveguide structures based on dispersive optical nonlinearities. Basic optical logic functions, such as digital pattern recognition, symbolic substitution, and all-optical compare-and-exchange operation are demonstrated using ZnS and ZnSe nonlinear interference filters. Differential gain, cascading, and optical latching circuits are demonstrated using GaAs/AlGaAs multiple-quantum-well nonlinear etalons that are compatible with diode-laser sources, and the relationship between differential gain and device response time is established through a thorough investigation of the switching dynamics. Preliminary results also indicate that optical fibers can be used as interconnects between optical logic gates. Picosecond all-optical switching with good (> 3:1) contrast is demonstrated for the first time in single-mode strip-loaded GaAs/AlGaAs nonlinear directional couplers (NLDC's). The anisotropy of quantum-well structure to light polarization is used to achieve polarization-dependent two-beam switching, and the optical Stark effect is used to demonstrate all-optical modulation in an NLDC with subpicosecond recovery time.
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BRUHNS, THOMAS VICTOR. "HARDWARE AND SOFTWARE FOR A COMPUTER CONTROLLED LIDAR SYSTEM." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188042.
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The hardware and software for a computer controlled optical radar, or lidar, system are described. The system builds on a previously installed pulsed ruby backscatter lidar, capable of acquiring data at controlled azimuth and elevation angles through the atmosphere. The described system replaces hardwired logic with computer control. Two coupled computers are used to allow a degree of real time control while data are processed. One of these computers reads and controls mount elevation angle, reads the laser energy monitor, and senses firing of the laser. The other computer serves as a user interface, and receives the lidar return data from a digitizer and memory, and the angle and energy information from the other computer. The second computer also outputs data to a disc drive. The software provided with the system is described, and the feasibility of additional software for both control and data processing is explored. Particular attention is given to data integrity and instrument and computer operation in the presence of the high energy pulses used to drive the laser. A previously described laser energy monitor has been improved to isolate it from laser transients. Mount elevation angles are monitored with an absolute angle readout. As a troubleshooting aid, a simulator with an output that approximates the lidar receiver output was developed. Its output is digitally generated and provides a known repetitive signal. Operating procedures are described for standard data acquisition, and troubleshooting is outlined. The system can be used by a relatively inexperienced operator; English sentences are displayed on the system console CRT terminal to lead the operator through data acquisition once the system hardware is turned on. A brief synopsis of data acquired on the system is given. Those data are used as the basis of other referenced papers. It constitutes soundings for over one hundred days. One high point has been operation of the system in conjunction with a balloon borne atmospheric particulate sampling package. The system has also been used occasionally as the transmitter of a lidar system with physically separated receiver and transmitter.
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Ma, Ruijin. "Building model reconstruction from lidar data and aerial photographs /." Ann Arbor : UMI Dissertation Services, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1104114425.
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Ozharar, Sarper. "STABLE OPTICAL FREQUENCY COMB GENERATION AND APPLICATIONS IN ARBITRARY WAVEFORM GENERATION, SIGNAL PROCESSING AND OPTICAL DATA M." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3516.
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This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the electronic waveform generator, and the RF carrier frequency is limited by the bandwidth of the photodetector. Similarly, using parabolic phase modulation together with time division multiplexing, RF chirp extension has been realized. Another application of the optical frequency combs studied in this thesis is real time data mining in a bit stream. A novel optoelectronic logic gate has been developed for this application and used to detect an 8 bit long target pattern. Also another approach based on orthogonal Hadamard codes have been proposed and explained in detail. Also novel intracavity modulation schemes have been investigated and applied for various applications such as a) improving rational harmonic modelocking for repetition rate multiplication and pulse to pulse amplitude equalization, b) frequency skewed pulse generation for ranging and c) intracavity active phase modulation in amplitude modulated modelocked lasers for supermode noise spur suppression and integrated jitter reduction. The thesis concludes with comments on the future work and next steps to improve some of the results presented in this work.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Sahin, Gokhan. "Service and restoration routing and wavelength assignment and restoration signaling in optical networks /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/6022.
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Matalgah, Mustafa M. "Geometric theory for designing optical binary amplitude and binary phase-only filters /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9717158.
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Cropanese, Frank C. "Synthesis of low k1 projection lithography utilizing interferometry /." Link to online version, 2005. https://ritdml.rit.edu/dspace/handle/1850/1235.
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van, der Gracht Joseph. "Partially coherent image enhancement by source modification." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/13379.
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Reeves, Stanley J. "A cross-validation approach to image restoration and blur identification." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/13414.
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Lane, Dallas W. "Signal processing methods for airborne lidar bathymetry." Title page, table of contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09ENS/09ensl265.pdf.
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"August 2001." Includes bibliographical references (leaves 77-80). Examines the susceptibility of existing signal processing methods to errors and identifies other possible causes of depth error not accounted for by existing signal processing methods, by analysis of the detected laser return waveform data. Methods to improve depth accuracy are investigated.
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Rijhwani, Vishal. "A biologically inspired optical flow system for motion detection and object identification." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5064.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 7, 2008) Includes bibliographical references.
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Rasakanthan, Janarthanan. "Advances in characterisation, calibration and data processing speed of optical coherence tomography systems." Thesis, Aston University, 2015. http://publications.aston.ac.uk/25260/.
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This thesis describes advances in the characterisation, calibration and data processing of optical coherence tomography (OCT) systems. Femtosecond (fs) laser inscription was used for producing OCT-phantoms. Transparent materials are generally inert to infra-red radiations, but with fs lasers material modification occurs via non-linear processes when the highly focused light source interacts with the materials. This modification is confined to the focal volume and is highly reproducible. In order to select the best inscription parameters, combination of different inscription parameters were tested, using three fs laser systems, with different operating properties, on a variety of materials. This facilitated the understanding of the key characteristics of the produced structures with the aim of producing viable OCT-phantoms. Finally, OCT-phantoms were successfully designed and fabricated in fused silica. The use of these phantoms to characterise many properties (resolution, distortion, sensitivity decay, scan linearity) of an OCT system was demonstrated. Quantitative methods were developed to support the characterisation of an OCT system collecting images from phantoms and also to improve the quality of the OCT images. Characterisation methods include the measurement of the spatially variant resolution (point spread function (PSF) and modulation transfer function (MTF)), sensitivity and distortion. Processing of OCT data is a computer intensive process. Standard central processing unit (CPU) based processing might take several minutes to a few hours to process acquired data, thus data processing is a significant bottleneck. An alternative choice is to use expensive hardware-based processing such as field programmable gate arrays (FPGAs). However, recently graphics processing unit (GPU) based data processing methods have been developed to minimize this data processing and rendering time. These processing techniques include standard-processing methods which includes a set of algorithms to process the raw data (interference) obtained by the detector and generate A-scans. The work presented here describes accelerated data processing and post processing techniques for OCT systems. The GPU based processing developed, during the PhD, was later implemented into a custom built Fourier domain optical coherence tomography (FD-OCT) system. This system currently processes and renders data in real time. Processing throughput of this system is currently limited by the camera capture rate. OCTphantoms have been heavily used for the qualitative characterization and adjustment/ fine tuning of the operating conditions of OCT system. Currently, investigations are under way to characterize OCT systems using our phantoms. The work presented in this thesis demonstrate several novel techniques of fabricating OCT-phantoms and accelerating OCT data processing using GPUs. In the process of developing phantoms and quantitative methods, a thorough understanding and practical knowledge of OCT and fs laser processing systems was developed. This understanding leads to several novel pieces of research that are not only relevant to OCT but have broader importance. For example, extensive understanding of the properties of fs inscribed structures will be useful in other photonic application such as making of phase mask, wave guides and microfluidic channels. Acceleration of data processing with GPUs is also useful in other fields.
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Hanson, Craig Demorest 1956. "Demonstration of capabilities of gallium arsenide etalons for practical optical logic." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277204.
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All-optical logic gates made from GaAs etalons were studied to see if they may be useful for optical computing. We have demonstrated that GaAs etalons may produce a change in output optical signal four times larger than the change in the input signal, and that the contrast of the output signal may be as high as 10 to 1. We have cascaded two GaAs etalons, i.e. the output change in the first causes the second one to switch. We have combined two signal beams and a biasing beam onto a GaAs etalon using polarized beams for a fan-in investigation, and have demonstrated that this setup may be used as an all-optical AND gate. We have also shown that GaAs etalons function well when interfaced to optical fibers by direct butt-coupling. Interconnections between all-optical gates by optical fibers, holographic optical elements, and conventional lenses are discussed.
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Yu, Donggang, and dyu@venus it swin edu au. "Processing and recognition of document and GIS images." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20050812.095914.
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In intelligent document processing system and geographical information systems (GIS), the image processing and recognition play an important role. This thesis deals with various problems in processing images in documents and GIS: image smoothing, filling, linearization and extraction of contour features, extraction of structural points, separation and recognition of spurious segments in handwritten digits, reconstruction and recognition of broken digits, and separation and recognition of colour document and GIS images. These approaches are also called Optical Character Recognition (OCR).
A new smoothing technique is developed to smooth follow contours of image. With the new smoothing algorithms, spurious pixels (points) of contours are removed based on smooth patterns, and smooth followed contours are found. Also, skeletons of image can be smoothed between neighboring �end� and �junction� points. Smooth following makes linearization of smoothed contours possible based on Freeman codes.
A new filling algorithm of contours, project filling, is described based on two kinds of structural patterns. By this method, any complicated contours of images can be filled correctly.
Different from other linearization methods, linearization and feature extraction of smoothed contours are based on difference chain codes. Curvature and bend angles of linearized are found. The convexity and concavity of linearized are described. In this way, a series of description features of contours is formed.
Structural points are new and useful features to describe morphological structures between neighboring linearized lines. Extraction of structural points is based on structural patterns which are determined by element chain codes. Also, extension Freeman codes are used in this thesis. Structural points make description and recognition of contours possible.
In order to recognize handwritten digits in document processing systems, separation of spurious segments, reconstruction of broken digits and recognition of handwritten digits are investigated. Experiments with large number of testing data set show satisfactory results for these algorithms.
Separation and recognition of colour document and GIS images are discussed. Object images of document and GIS images are extracted based on the description of shape structures, prior knowledge and color information, which are associated with each other. Color images can be described by a limited number of colors in color document and GIS images. Therefore, separation of color image is done by color reduction method, and recognition of object images is based on structure patterns, prior knowledge and colour information. It can be seen that specific information should be considered in many practical problems to achieve better processing results.
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Ceremuga, Joseph Thomas II. "Optimizing inspection of high aspect ratio microstructure using a programmable optical microscope." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5394.
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Ceremuga, Joseph Thomas. "Optimizing inspection of high aspect ratio microstructure using a programmable optical microscope." Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180101/unrestricted/ceremuga%5Fjoseph%5Ft%5F200312%5Fms.pdf.
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Beard, Daniel Palaniappan K. "Firefly web-based interactive tool for the visualization and validation of image processing algorithms /." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/5346.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on December 21, 2009. Thesis advisor: Dr. Kannappan Palaniappan. Includes bibliographical references.
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Motahari, Bidgoli Seyed Mohammad Amin. "An Optical Design Configuration for Wireless Data Transmission." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2439.
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The concept of 2D barcodes is of great relevance for use in wireless data transmission between handheld electronic devices. In a typical setup, any file on a cell phone for example can be transferred to a second cell phone through a series of images on the LCD which are then captured and decoded through the camera of the second cell phone. In this research, a new approach for data modulation in 2D barcodes is introduced, and its performance is evaluated in comparison to other standard methods of barcode modulation. In the proposed method, Orthogonal Frequency Division Multiplexing (OFDM) modulation is used together with Differential Phase Shift Keying (DPSK) over adjacent frequency domain elements to modulate intensity of individual pixels. It is shown that the bit error rate performance of the proposed system is superior to the current state of the art in various scenarios. A specific aim of this study is to establish a system that is proven tolerant to camera motion, picture blur and light leakage within neighboring pixels of an LCD. Furthermore, intensity modulation requires the input signal used to modulate a light source to be positive, which requires the addition of a dc bias. In the meantime, the high crest factor of OFDM requires a lower modulation index to limit clipping distortion. These two factors result in poor power efficiency in radio over fiber applications in which signal bandwidth is generally much less than the carrier frequency. In this study, it is shown that clipping a bipolar radio frequency signal at zero level, when it has a carrier frequency sufficiently higher than its bandwidth, results in negligible distortion in the pass band and most of the distortion power is concentrated in the baseband. Consequently, with less power provided to the optical carrier, higher power efficiencies and better receiver sensitivity will result. Finally, a more efficient optical integrated system is introduced to implement the proposed intensity modulation method which is optimized for radio over fiber applications.