Photoelastic fringe pattern analysis by real-time phase-shifting method

This paper describes high-speed phase-shifting method for the real-time analysis of isochromatic and isoclinic parameters in photoelasticity. By rotating an analyzer at a constant rate and an output quarter-wave plate at a double rate of the analyzer and recording images by a CCD camera continuously, sequential phase-shifted images whose brightness is integrated by sensors are obtained. Then, the distributions of the isochromatic and isoclinic parameters are obtained at a video rate using the proposed phase-shifting algorithm. The phase distributions of the isochromatic and isoclinic parameters of a disk under the static and increasing loadings are simulated. Then, an application of the proposed method to a problem under increasing load is demonstrated and the time variation of the isochromatic parameter is evaluated. (C) 2002 Elsevier Science Ltd. All rights reserved.