Transmission variations in liquid crystal spatial light modulators caused by interference and diffraction effects
Abstract
We report on the characteristics of a newly developed high- resolution (640 X 480 pixels) parallel-aligned liquid crystal spatial light modulator (LCSLM) as a function of wavelength. Phase-only operation over a range of 2 (pi) rad is easily achieved by operating at shorter wavelengths. We also measure an unexpected effect--the transmitted light intensity changes with applied voltage. Our experiments show that thin-film interference and pixel diffraction effects are responsible for this observed behavior. The diffraction effect is caused by a nonuniform electric field across each pixel. This nonuniform electric field introduces a blazing effect that changes the intensity distribution in the various diffracted orders as a function of applied voltage. These same kinds of effects have been observed with several other twisted-nematic LCSLMs. Because of the complicated polarization effects caused by these twisted-nematic liquid crystal devices, however, the diffraction and interference effects are more easily studied using a parallel-aligned LCSLM.
- Publication:
-
Optical Engineering
- Pub Date:
- June 1999
- DOI:
- 10.1117/1.602149
- Bibcode:
- 1999OptEn..38.1051D