[OPTICAL REVIEW Vol. 3, No. 2 (1996) 89-95]

Grayscale-Memory Spatial Light Modulator with Polymer-Dispersed Phase-Transition Liquid Crystal

Hideo FUJIKAKE, Kuniharu TAKIZAWA, Hiroshi KIKUCHI, Takanori FUJII, Masahiro KAWAKITA and Minori YOKOZAWA

NHK Science & Technical Research Laboratories, 1-10-11, Kinuta, Setagaya-ku, Tokyo, 157 Japan

(Received August 17, 1995; Accepted January 11, 1996)

A new storage-type spatial light modulator has been developed which uses a polymer-dispersed phase-transition liquid crystal film and a photoconductor for high-brightness projection displays. The liquid crystal film containing micrometer-sized chiral nematic liquid crystal domains subdivided by a unique honeycomb polymer network functions as a memory layer for an input image. The liquid crystal domains independently maintain the binary alignment states in the opaque (light-scattering) cholesteric phase or transparent nematic phase. Grayscale images can be displayed according to the spatial distribution of the bistable liquid crystal domains. The device exhibits rapid response of a few ms and a limiting resolution of 32 lp/mm. It has the advantages of high transmittance without polarizers and ease of fabrication due to the free-standing liquid crystal film.

Key words : spatial light modulator, grayscale image memory, polymer-dispersed liquid crystal, liquid crystal polydomain structure, cholesteric-nematic phase transition, Bi12SiO20 photoconductive crystal