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 28 for “"Laser Speckle"”.
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A laser speckle based position sensing technique
… presents 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. …
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Laser speckle photography for surface tampering detection
… that 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 …
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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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Laser speckle modeling for three-dimensional metrology and LADAR
In 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 …
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A large-scale three-dimensional imaging system based on laser speckle
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
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Learning-based Correlation Analysis Between Laser Speckle and Surface Size Distribution
… folds upon propagation, resulting in complex speckle patterns. One specific application is the drying of wet powders in the pharmaceutical industry, where quantifying the particle size distribution (PSD) is of particular interest. A non-invasive and real-time monitoring probe in the drying …
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3D imaging methods for manufacturing, with emphasis on the laser speckle technique
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.
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Measurements of Surface Displacements During Stress Wave Propagation in Opaque Solids Using Pulsed Laser Speckle Photography
… The system consists of combining a pulsed ruby laser source and an optical speckle photography recording scheme. The set-up is capable of measuring surface displacements due to stress waves and propagating cracks in solids. A double exposure recording allows the comparison of object points to be …
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Optimal standoff imaging using structured laser illumination and graphical models
… detector array. A series of spatially-structured laser pulses is cast on the scene of interest, and a single-detector power measurement is made on the light each pulse returns from the scene. There has been significant interest in the "ghost imaging" configuration, in which the spatial patterns …
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Multimodal imaging monitoring of key physiological changes of peripheral arterial disease
… use a multimodal imaging approach starting with Laser Speckle Contrast Imaging (LSCI) and Power Doppler ultrasound for perfusion (superficial and deep tissue, respectively); followed by fluorescent imaging of hypoxia and imaging both angiogenesis and metabolism using molecular PET probes. …
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An investigation of the measurement, fixturing, and trimming of large sheet metal parts
… is being researched and developed using laser speckle wavelength decorrelation. This method is still in development but initial results show that this method will decrease measurement time, decrease the amount of precision hardware needed, and decouple accuracy with the range of the …
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Retinal Ischemia in the In Vivo Rodent: Cellular and Vascular Characteristics
… examined by using an imaging technique known as laser speckle flowmetry (LSF) to generate two dimensional maps of blood flow changes. We demonstrated that the inner retinal and choroidal circulations could be imaged noninvasively, and used this technique to study functional hyperemia responses in …
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Magnetically Actuated Microrobots for Tissue Elasticity Mapping in Colorectal Cancer Diagnosis
… approach combining magnetic microrobots with laser speckle contrast imaging, accurately quantifying variations in tissue stiffness, confirming the methods sensitivity and clinical potential. The compact, non-contact design of microrobotic systems makes them suitable for integration with …
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Three dimensional simulation of functional neuro-vascular imaging
… mapping of oxygen tension in plasma (pO2), and Laser Speckle Contrast Imaging (LSCI) has been demonstrated to provide qualitative assessments of blood flow in the cortex. However, as both of these methods provide physiological parameters based on the spatial sampling of photons arriving at a …
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Non-invasive objective assessment of diabetic foot ulcer healing with blood perfusion and tissue oxygenation
… and transcutaneous oxygen saturation (StO2). The laser speckle integrated multispectral imaging system is an optical, non�invasive system that is able to provide quantitative and visual information of blood perfusion and tissue oxygen in diabetic ulcer. The estimation of blood perfusion is based …
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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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Small displacement measurement in ultrasound: quantitative optical noncontacting detection methods
… description and development of intensity-based laser interferometric techniques for the detection and measurement of ultrasonic stress waves and their small displacement amplitudes is presented. The dynamic displacement sensitive interferometers described in the following chapters allow the …
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Transport properties of a Bose-Einstein condensate with tunable interactions in the presence of a disordered or single defect potential
… clean BEC system using the light field from a laser speckle pattern. Using this system, we have investigated the effects of disorder or a single Gaussian defect, on the collective dipole motion of a BEC of 7Li in an optical trap. In addition, we perform transport experiments on a weakly …
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