<title>Influence of phototransformed molecules on optical properties of finite cholesteric liquid-crystal cell</title>

Abstract

A cholesteric liquid crystal (CLC) is considered in a cell with planar boundary conditions, in which long-lived metastable states of molecules with conformation different from that of initial molecules are formed under the action of light. It was suggested that the phenomenon of molecular phototransformation be used for varying the cholesteric twisting ability and thus for controlling the CLC pitch and the wavelength of light selectively reflected from the CLC cell. The dependence of the pitch on both the molecular twisting ability and the anchoring energy of CLC with oriented cell planes was investigated. The expression is derived for the anchoring energy which makes it possible to determine its value through the experimentally measured data. It is shown that with discontinuous change of a pitch there may occur a jump of mean values of components of the CLC dielectric susceptibility tensor. The CLC pitch relaxation appearing on switching off the light was considered.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.