Fast photoconductor coupled liquid-crystal light valve

Abstract

Short low-energy pulses of laser light have been used to switch spots on a liquid crystal (LC) through a coupled photoconductive film of glow-discharge-produced amorphous Si (GD/a-Si). The a-Si responds rapidly to a light pulse, yet retains sufficient photoconductivity in the slow portion of the decay to match the slower response time of the LC. Spots have been written with laser pulses 10 μs long, about 10−3 the response time of the LC, and with a pulse energy of 1–10 μJ/cm2, less than 10−4 the energy required for thermal writing.