Characterization of a liquid crystal variable retarder by Mueller matrix ellipsometry

With the maturing of liquid crystal technology, liquid crystal variable retarder (LCVR) has been widely used in optical systems. In practice, it is of great importance to characterize the polarization properties of the LCVR for its control and applications to accurately modulate the polarization state of the light in the optical systems. In this paper, the Mueller matrix ellipsometry (MME) is applied to comprehensively characterize the polarization properties including the retardance and the fast axis azimuth of the LCVR versus the driving voltage, the wavelength, as well as the incidence and the azimuth of the light. An analytical model is constructed to describe the LCVR based on the Mueller matrix calculus, in which the influences of the incidence and the azimuth of the light are considered. A house-developed spectroscopic Mueller matrix ellipsometer is employed to perform the experiments. Simulations and experiments about a commercial LCVR product are presented and discussed to verify the proposed method.