OPTIMIZATION OF FERROELECTRIC LIQUID-CRYSTAL OPTICALLY ADDRESSED SPATIAL LIGHT-MODULATOR PERFORMANCE

The switching mechanisms of ferroelectric liquid crystal optically add ressed spatial light modulators (OASLMs) using a photosensitive struct ure made of an intrinsic amorphous silicon layer sandwiched in between an indium tin oxide coated glass sheet and a reflective metal layer a re reviewed. Devices based on photoconductor and photodiode layers are briefly reviewed and attention is focused on pixelated metal mirror ( PMM) devices, which offer fast switching and good optical characterist ics with the same sensitivity range as the photodiode OASLMs. They are particularly suitable for high frame rate SLMs with intense read beam s. Optimum drive conditions for this type of device are considered. An equivalent electrical circuit is proposed for the photosensitive stru cture and the voltage drop across the liquid crystal layer is investig ated and related to the optical response of the device. Experimental w ork is carried out to demonstrate the validity of our equivalent circu it. We show that the synchronization of a light source with the case p ulse enables the OASLM to work at frame rates of a few kilohertz. We a lso demonstrate that the exact synchronization of the write light sour ce with the write pulse enhances the potential memory of the device. ( C) 1997 Society oi Photo-Optical Instrumentation Engineers.