Extended linear polarimeter to measure retardance and flicker: application to liquid crystal on silicon devices in two working geometries

Abstract

We focus on the evaluation of the applicability of the classical and well-established linear polarimeter to the measurement of linear retardance in the presence of phase flicker. This analysis shows that there are large errors in the results provided by the linear polarimeter when measuring the linear retardance of a device. These errors depend on the specific retardance value under measurement. We show that there are some points where this limitation can be used to measure the fluctuation amplitude consistently. An elegant method is further proposed, enabling the measurement of the average retardance value, thus extending the applicability of the classical linear polarimeter. Experimental characterization results are provided for various electrical sequences addressed onto a parallel aligned liquid crystal on silicon (LCoS) display. Good agreement is obtained with experiment, thus validating the linear polarimeter methodology proposed. Furthermore, results are provided for the LCoS in two reflection geometries, perpendicular incidence with and without nonpolarizing beam splitter, demonstrating robustness of the method. As a result, the evaluation of both phase modulation range and flicker magnitude for any electrical sequence addressed can be easily obtained, which is very important for optimal use of LCoS displays in applications.