ELECTROOPTIC EFFECT IN POLYMER-DISPERSED CHOLESTERIC LIQUID-CRYSTALS WITH MEDIUM CHIRALITY

We have investigated the electro-optic behaviour of polymer sheets con taining small chiral nematic liquid crystal droplets. In previous inve stigations of polymer-dispersed liquid crystals (PDLC), either non-chi ral nematic liquid crystals or cholesteric liquid crystals with very s mall pitch (p < lambda) have been used. Here we adjusted the pitch p t o be below the Mauguin limit, but well above the wavelength, lambda, o f the visible range of light; typically we chose p approximate to 2 la mbda/Delta n. Between crossed polarizers, the sample can be switched f rom a transparent off state to a dark on state. With respect to non-ch iral nematic PDLC films, the transmittance is lower, but the angular d ependence is improved.