Electrically Induced Light Scattering from Anisotropic Gels with Negative Dielectric Anisotropy

Homeotropically aligned gels were obtained by photo-induced cross linking of a liquid crystalline (LC) mixture containing LC diacrylates and conventional LC molecules with negative dielectric anisotropy. The gels produced in this way were very clear as observed from all directions. When an electric field was applied across the gel, its appearance changed and a light scattering texture was formed. The intensity of the scattered light increased non-linearly with increasing voltage in a reversible way. Light scattered by the gels was not polarised and, especially at high voltages, the scattering efficiency of the gels was found to be independent of the direction of the incident light. In the case of gels containing dye molecules, scattering was combined with absorption. In this way grey levels for dye absorption could be obtained.