Phase measurements of a twisted nematic liquid crystal spatial light modulator with a common-path interferometer

We present a novel and high accuracy (+/-1 degrees) technique for measuring the difference in phase delay between the positive and negative eigenvecto rs of a twisted nematic liquid crystal spatial light modulator (LCSLM) as a function of applied voltage. We show a new architecture for a common-path interferometer where we simultaneously generate both the positive and negat ive eigenvectors of the LCSLM, We use an electro-optic light modulator to p rovide a time varying phase shift between the two eigenvectors and measure the phase delay difference between the two eigenvectors, We compare the pha se delay values with those obtained using a Mach-Zehnder interferometer and find good agreement, (C) 2001 Published by Elsevier Science B,V.