Optical measurement of the director relaxation time in a periodically reoriented nematic liquid crystal

Abstract

A method is proposed to determine the decay time of the nematic director under condition of temporarily zero electric field across the nematic layer. It is based on a linearized theory of the electrohydrodynamic instability of nematic liquid crystals and on the optical theory of the diffraction grating action of a periodically reoriented nematic layer. The method provides further experimental information on material parameters by experimental investigation of the dependence of the director relaxation time on the distortion wave number.