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Proceedings Paper

Phase extracting and unwrapping algorithm of electrical speckle shearing phase-shifting pattern interferometry
Author(s): Chao Jing; Ping Zhou; Yimo Zhang
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Paper Abstract

Electrical Speckle Shearing Phase-shifting Pattern Interferometry (ESSPPI) has been used in the fields of nondestructive testing (NDT) and stress field analysis as a precise deformation measuring method. The general fixed-step phase extracting algorithms of ESSPPI, such as three-step algorithms, four-step algorithms, five-step algorithms, and their corresponding errors are analyzed. It is proved that the phase accuracy of ESSPPI with different algorithms are mainly affected by linear error of phase-shifting. Therefore the modified four-step phase-shifting extracting algorithm that isn’t sensitive to linear error of phase-shifting is adopted in the paper. The filtering algorithm should be employed to reduce the influences of speckle noise and wrong data caused by errors during measurement. Then the least-squares phase-unwrapping algorithm based on fast discrete cosine transform (LPABFDCT) is adopted to search the least-squares solutions between phase difference value of adjacent pixels and unwrapped phase difference value of the pixels and the real phase distribution caused by object deformation is obtained. The Electrical Speckle Shearing Phase-shifting Pattern Interferometric images are captured with four-step phase-shifting method and the real phase distributing image is achieved with modified four-step phase-shifting extracting algorithm, denoising filter and the least-squares phase-unwrapping algorithm based on fast discrete cosine transform. It is proved with experiment results that the real phase distributing images are effective achieved by mean of combination of average filter and the least-squares phase-unwrapping algorithm based on fast discrete cosine transform.

Paper Details

Date Published: 31 October 2016
PDF: 8 pages
Proc. SPIE 10022, Holography, Diffractive Optics, and Applications VII, 100222B (31 October 2016); doi: 10.1117/12.2247750
Show Author Affiliations
Chao Jing, Science and Technology on Optical Radiation Lab. (China)
Ping Zhou, Science and Technology on Optical Radiation Lab. (China)
Yimo Zhang, Tianjin Univ. (China)


Published in SPIE Proceedings Vol. 10022:
Holography, Diffractive Optics, and Applications VII
Yunlong Sheng; Chongxiu Yu; Changhe Zhou, Editor(s)

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