Photoelastic modulation polarimetry and its measurement of twisted nematic liquid crystal

Abstract

For in situ/real time measurement, a retarder is substituted by a photoelastic modulator (PEM) in a polarimetry. The azimuthal position of the strain axis of PEM is directly determined with respect to the orientation of the transmission axis of polarizer and analyzer. The Mueller matrix of a twisted nematic liquid crystal (TN-LCD) is derived analytically. The phase retardation and the twisted angle of a TN-LCD are numerically obtained through two successive measurements of the Mueller polarimeter.