Spatial and temporal light modulator of the photosemiconductor–liquid crystal type exhibiting texture and cholesteric–nematic transitions

A study was made of the operating characteristics of a spatial and temporal light modulator of the photosemiconductor–liquid crystal type exhibiting an orientational texture transition as well as a cholesteric–nematic phase transition. The photosemiconductor was a chalcogenide film of the selenium–arsenic type and the liquid crystal was a composite based on cyanbiphenyls, azoxy compounds, complex esters, and tolans. The modulator could be used for reversible recording, long-term storage, and positive and negative imaging without recourse to polarization optics or preliminary orientation of the liquid crystal. The maximum sensitivity was 1 μ W/cm², the resolution was at least 65 pairs of lines/mm, and the minimum write–erase cycle time was 0.75 sec.