Abstract

The phase modulation properties of a twisted-nematic liquid crystal television have been widely reported. However, the phase modulation depth depends on various factors, such as the birefringence of the liquid crystal material, the thickness of the cell and the wavelength of the illuminating light.¹ When the modulation depth is equal to 2π, a phase ramp with maximum phase that is much larger than 2π can be displayed on a liquid crystal panel as a sawtooth phase variation with a maximum height of 2π. These sawtooth phase fronts then act as a series of prisms that deflect the incoming beam. Thus, in principle, we may create a programmable prism for beam steering purposes, which could be used in optical imaging or multiplex hologram applications. However, most of the commercially available LCTVs are unable to attain the 2π phase modulation depth. In this paper we discuss the effect of this limited modulation depth and provide some experimental verification of beam steering by using an LCTV having a modulation depth of it.

© 1992 Optical Society of America