Imaging Science Ph.D. Defense: Biswa Swain
Ph.D. Dissertation Defense
Optical Differentiation Wavefront Sensor with Pixelated Filters Toward High Performance Metrology
Imaging Science Ph.D. Candidate
Chester F. Carlson Center for Imaging Science, RIT
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Freeform optics enables enhanced system performance and packaging due to the high degrees of design freedom they provide, but characterizing these optics remains challenging. Phase measurement of an optical wave is essential in the metrology of optical components, adaptive optics, and laser beam quality assessment. The Shack-Hartman Wavefront Sensors are limited by their dynamic range and resolution due to lenslet operation. Interferometric-method-based on adaptive nulling requires high-performance wavefront sensor, and coordinate-scanning-based measurements are time consuming. We investigate and develop an Optical Differentiation Wavefront Sensor (ODWS) based on binary pixelated filter towards enabling high dynamic range, high resolution freeform metrology. Analysis of experimental results and comparison with commercial metrology shows that phase plates with diﬀerent magnitude of wavefront slopes can be accurately characterized. We created an ODWS design that reduced the footprint. We further investigated the system alignment tolerance. We report the theoretical and experimental demonstration of an ODWS based on binary pixelated linear and nonlinear amplitude filtering in the far-field. We trained and tested convolutional neural network that reconstructs spatial phase map from nonlinear filter based ODWS images where an analytic solution is not available. It shows accurate retrieval over different magnitude of wavefronts and on random shaped wavefronts. This work paves the way for implementation of simultaneous sensitive, high dynamic range and high-resolution wavefront sensing.
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