In the field of optical measurement, phase always represents the physical quantity to be measured. Thus phase extraction from fringe pattern is a key step for quantitative measurement and evaluation. Much research work has been conducted to develop effective phase evaluation methods such as fringe tracking and fringe skeleton in early years, and the more precise method of phase shifting and Fourier transform techniques in recent decades. For accurate phase evaluation, phase shifting method requires three or more phase-shifted fringe patterns at each deformed stage, thus it is not suitable for continuous deformation measurement. Fourier transform, on the other hand, requires a high frequency carrier fringe for phase separation in the spectrum domain, which places stringent requirement on experiment arrangement. Thus it would be desirable to develop a convenient method to retrieve the modulated phase from a single fringe pattern. In this paper, we propose a clustering approach which utilizes the phase clustering property to extract phase information from a single interference specklegram. To explore the workability and limitations of the proposed technique, typical shearographic fringe patterns are used for phase evaluation. Results obtained are similar to those from standard 4-step phase-shifting method with similar accuracy. Non-repeatable continuous movement is also measured by the proposed method, and the results confirm the robustness and accuracy of the proposed clustering phase extraction method.

Date Published: 25 August 2009
PDF: 6 pages
Proc. SPIE 7375, ICEM 2008: International Conference on Experimental Mechanics 2008, 737548 (25 August 2009); doi: 10.1117/12.839283

Published in SPIE Proceedings Vol. 7375:
ICEM 2008: International Conference on Experimental Mechanics 2008
Xiaoyuan He; Huimin Xie; YiLan Kang, Editor(s)