Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 167 for “"Speckle"”.
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Nuclear speckle dynamics and function of speckle association in gene expression
Nuclear speckles have been studied intensively for a long time. Accumulating evidence has suggested that nuclear speckles have a dynamic structure, and are associated with a significant fraction of active chromosome regions and genes. However, their mobility and the regulation mechanism of their …
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Boundary detection in ultrasonic speckle
… problem of detecting boundaries in ultrasound speckle imagery. For physiological reasons, we argue that boundaries between tissue layers appear as lines in ultrasound scans and approach the boundary detection problem as one of detecting lines of unknown orientation. We define a set of …
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Speckle reduction in SAR imagery
… is a type of multiplicative noise known as speckle. There are a number of different approaches which may be taken in order to reduce the amount of speckle noise in SAR imagery. One of the approaches is termed post image formation processing and this is the main concern of this thesis. …
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A laser speckle based position sensing technique
… the design and development of a novel laser-speckle-based position sensing technique. In our prototype implementation, a He-Ne laser beam is directed at the surface of an air-bearing spindle. An imaging system is set up to capture speckle patterns scattered from the spindle surface. These …
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Laser radar tomography--the effects of speckle
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1991.
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Laser speckle photography for surface tampering detection
… combines computational photography and laser speckle imaging. Without requiring controlled laboratory conditions, our method is able to detect surface changes that would be indistinguishable in regular photographs. It is also mobile and does not need to be present at the time of contact with …
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Estudio de la magnetostricción por interferometría de Speckle
… de materiales magnéticos por interferometría de speckle. En la primera parte, se recogen los fundamentos teóricos del fenómeno del speckle y de las técnicas experimentales que se aplican en el desarrollo de este trabajo. En la segunda parte, se analizan las bases teóricas de la magnetostricción, …
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Speckle applications for volumetric imaging of biological dynamics
Speckle is a high contrast granular pattern formed by coherent light interactions with rough surfaces or biological tissue. The speckle intensity fluctuates in space (or time) in a "random" manner and this randomness is often treated as noise in optical imaging. In another perspective, the speckle …
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Modal testing using high speed digital speckle pattern interferometry
… introduces the application of a high-speed speckle pattern interferometer (SPI) to perform quantified impact modal testing. The interferometer acts as a non-contact multipoint vibrometer that removes the mass-loading effects of contact transducers to improve measurement accuracy and …
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Laser Speckle Imaging: A Quantitative Tool for Flow Analysis
<p>Laser speckle imaging, often referred to as laser speckle contrast analysis (LASCA), has been sought after as a quasi-real-time, full-field, flow visualization method. It has been proven to be a valid and reliable qualitative method, but there has yet to be any definitive consensus on its …
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Sparse Aperture Speckle Interferometry Telescope Active Optics Control System
… within 16 nm. This is accurate enough to perform speckle analysis for the visible light spectrum. The mirrors used in testing were not supported with a whiffletree and produced trefoil-like aberrations which made phasing two mirrors difficult.</p> <p>The active optics system was able to …
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Mapping cerebral blood flow with speckle contrast optical spectroscopy
… do not have sufficient signal-to-noise ratio. Speckle contrast optical spectroscopy (SCOS) has been previously considered as an alternative approach to use near-infrared light to measure CBF non-invasively in humans. Several advancements in use of SCOS for CBF measurement are presented here. A …
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Laser speckle modeling for three-dimensional metrology and LADAR
… this thesis, I developed three-dimensional laser-speckle models to help in the development process of three-dimensional optical-metrology imaging systems. These models were developed to aid in the proof of concept for various three-dimensional metrology techniques. These models were then compared …
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Ageing Assessment of Power Transformer Kraft Paper Insulation Using Optical Speckle
… and inexpensive optical setup based on optical speckle is the main subject of this thesis. Speckle interference patterns from a laser diode source have been captured by a CCD camera. Classification based on textural features shows very good discrimination between ageing classes making this …
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A New Look at the Theory of Double-Aperture Speckle Photography
… a spatial filtering setup for a double-apertures specklegram. Both the pointwise and full-field filtering setups are analyzed. The resulting equations are shown to be more complete and exact than the equations from the conventional Moire analysis.
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