Liquid crystal on silicon-based real time phase stepping interferometry by spatial multiplexing

In this paper, we present a method to perform phase-shifting interferometry in real time. The technique is based on the use of a parallel aligned liquid crystal on a silicon display as a customized reference mirror. In order to implement the four-step algorithm, a set of macropixels is programmed onto the display, and these are divided into four zones with the appropriate phase shifts. This way, by spatial multiplexing, it is possible to obtain the phase of the wavefront at a rate limited only by the integration time of the employed detector. The customized mirror is able to both compensate the initial curvature of the object under study and introduce the necessary phase shifts to perform phase calculation. Examples of the phase reconstruction of static and dynamic objects are shown.