Wedged Liquid Crystal Beam Steering Device

Abstract

Liquid crystals have long been investigated for non-mechanical beam steering devices. Previous work has approached beam steering by using an electrically addressed cell with multiple electrodes arranged in stripes. By creating a series of steps in the index of refraction profile, the beam experiences an effective wedge and is steered in a particular direction [1]. The discrete nature of the steps creates a substantial amount of scattering which can be reduced by the addition of a resistive region between electrodes to interpolate neighboring voltages [2]. Another method of beam steering is to create a voltage drop along one electrode which produces continuous phase profiles [3]. The steering angle is limited by the product of the change in index and thickness of the cell divided by the length of the cell. This creates a trade-off between switching speed and steering angle since the nematic relaxation time is proportional to the thickness squared.