Temporal Polarization Phase-shifting for Digital Speckle Pattern Interferometry

A temporal 4-step polarization phase-shifting technique for digital speckle pattern interferometry (DSPI) with one fixed and two rotatable polarizers is proposed. The fixed polarizer is used to filter out the reflected object beam in one polarization direction, and the two rotatable polarizers are used to perform the 4 times phase shifts. The Jones derivation illustrates the object surface phase distribution can be derived from the 4 speckle pattern interferograms, which are bright, gloomy, bright, and gloomy successively. The experiment shows that the proposed temporal polarization phase-shifting technique is able to extract the phase change caused by a tiny out-of-plane displacement. Unlike the PZT-driven phase-shifting, the polarization phase-shifting in this method is stable and accurate in the long term.