Orientational order of some liquid crystal/dye mixtures obtained from optical birefringence

ABSTRACT

This study presents optical birefringence measurements as a function of temperature for the liquid crystal/dye mixtures. The optical birefringence of the liquid crystals used in liquid crystal displays technology is related to the order parameter <P₂>, which is crucial from the development point of view. The properties of the dyes (4-dimethylamino-4′-nitrostilbene and N,N′-bis(2,5-di-tert-buthylphenyl)-3,4,9,10-perylenedicarboximide) as a guest molecule are tested over the whole region of nematic phase occurrence by three different methods: measurement with use of the plano-convex lens, Berek's compensator and photoelastic modulator.