Phase retardation dependent optical response time of parallel-aligned liquid crystals

Correlation between the director reorientation and its consequent optical response time of the parallel-aligned nematic liquid crystals was investigated. This optical decay time is found to depend on the phase retardation introduced by the liquid-crystal layer. To verify theory, dependence of optical decay time on three parameters—liquid-crystal thickness, wavelength, and birefringence (through temperature effect)—was demonstated. Taking the phase retardation dependence into consideration, the optical decay time measurement technique is a simple, convenient, and accurate method for characterizing the ratio of rotational viscosity and splay elastic constant of liquid crystals.