Electrically Controlled Birefringence of Thin Nematic Films

This paper reports field-induced realignment of a nematic liquid crystal. A thin nematic film, which has a negative dielectric anisotropy, is initially homeotropic. Application of a threshold field parallel to the optic axis distorts the nematic ordering and increases the film's birefringence in certain light-propagation directions. Experimental results are given for threshold voltage, threshold width, optical contrast ratio, frequency response, angular field of view, electrical power consumption, and transient response. Light-valve applications are described.