Phase extraction from random phase-shifted shadow moiré fringe patterns using stereovision technique

The measurement accuracy of phase shifting shadow moiré is affected by both the spatially nonuniform phase shift error and random phase shift error. Substantial work has been done to overcome this difficulty, but few works can deal with the two error sources simultaneously. In the presented paper, we describe a solution that can compensate for the two error sources at the same time. In our method, a binocular stereovision system is integrated into a shadow moiré configuration to calibrate the setting parameters. Thus, a precise measurement setup is built. Then, we developed an iterative least-squares algorithm to analyze the acquired three fringe patterns. The proposed algorithm can extract the measurement phase without nonuniform phase shift error. On the other hand, it can compensate the random phase shift error by calibrating the distance of grating translation using the least-squares fitting in spatial. Optical experiments show that the proposed method can effectively minimize the phase-shift error and that it possesses a superior performance than the existing typical phase shifting algorithm.