| Summary: | 碩士 === 國立中興大學 === 機械工程學系 === 89 === A comparison study of ESPI (electrical speckle pattern interferometry) technique is presented in this article. Both the widely used correlation fringe method and the rigorous direct-speckle-field-solving approach are fully studied in details. It goes from the optical setup, phase shifting technique, laser beam profile normalization, filtering, unwrapping, to the curve fitting of the result and the further error analysis related. A 3-D deformation field of size 16 x 13 cm2 is interested here with the usage of a 10-mW He-Ne laser. An automated self-marking phase-shifting algorithm is used to monitor the phase-shifting process and to provide the frames necessary for the phase map achievement. The newly developed beam profile normalization and noise-immune phase unwrapping algorithm by our lab are applied to the experimental work and has proved successful of the proposed algorithm. Consequently, the direct-speckle- field-solving method is the suggested solution of ESPI technique with the self-marking criterion monitoring the phase-shifting process and providing the frames needed and with the noise-immune algorithm straightly applied to the ill-conditioned wrapped map, regardless any corrupt data of it.
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