Instantaneous surface profile measurement using polarized phase-shifting

In this paper, an instantaneous phase-shifting interferometer (IPSI) is constructed, based on polarized light, to capture interference fringe images with different phase shifting instantaneously, and to avoid the effect of surrounding environments. The phase value is calculated according to the intensity of the interferometer images, and the surface profile of specimen can be determined after phase unwrapping. In experiments, the interference images are captured simultaneously by using four CCD cameras and the position mismatch of the four images are corrected by using digital image correlation (DIC). Tests of the measurement system on flat mirror, tilted mirror and wafer are given. An average error between 0.03μm̃0.05μm can be achieved, and the maximum error is about 0.1μm.