The Application of Optical Phase Unwrapping on a Vibrating Plate
Date Issued
2009
Date
2009
Author(s)
Chen, Jia-Feng
Abstract
The optical measurement has the merits of high-resolution and non-contact, and can also be applied to the system of fast-inspection. Therefore, this study uses the above advantages to continue the research about the earlier study of Dr. Shu-Hua Chang in the acoustic laboratory. We make the study in progress on the application of optical phase unwrapping to the vibrational mode on plates, and further confirm its precision. To greatly reduce the influence by the interference from environment, the lateral shearing interferometry of common optical path is used for this study. After getting interferometric fringe patterns, phase shifting interferometry and parallel 2π phase unwrapping are used to reconstruct the correct shapes of vibrational mode on plate in order to obtain the full-field mode shapes without the simulation of software. In order to obtain a better reconstruction of mode, the technique of digital image processing is used in this paper. Using the transformation of intensity can obtain the interferometric fringe patterns with much uniform light distribut and using Fourier transform filter to obtain more smooth image of reconstructed mode. Furthemore, it is to improve the mask of parallel 2π phase unwrapping for the convergent mask and the divergent mask, and to make comparison between them for various noises. Recently, industry in optics grows fastly in Taiwan. It is to be expected that the study of this paper can make the system of optical measurement in the acoustic laboratory to become more complete with quickly picking up characteristics and high-accuracy.
Subjects
Lateral Shearing Interferometry
Optical Phase Unwrapping
Phase Shifting Interferometry
Type
thesis
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