Interferometric phase measurements for polarization eigenvectors in twisted nematic liquid crystal spatial light modulators

We show interferometric measurements of the phase delays for both eigenvectors in a twisted nematic liquid crystal spatial Light modulator (LCSLM). These polarization eigenvectors are of interest for newer LCSLMs that are thinner and consequently have a lower birefringence compared with earlier devices. We use a new technique in which an electro-optic light modulator provides a time varying phase shift between the electric field components in the two arms of a Mach-Zehnder interferometer. The appropriate eigenvectors are generated and detected for a LCSLM located in one arm of the interferometer. We then use a lock-in amplifier to accurately measure the phase delay for the LCSLM as a function of applied voltage. Our experimental results show agreement with the theory. (C) 2000 Elsevier Science B.V. All rights reserved.