The theory of reflexion and transmission by plane parallel cholesteric films

Abstract

The theory of propagation in an infinite cholesteric medium is applied here to the problem of a sample bounded by plane parallel surfaces normal to the optic axis. For each circular polarization at normal incidence, the reflected and transmitted waves are found to consist of both circular polarizations. Thus, four coefficients of reflexion and transmission are needed to describe the problem fully. These have been calculated in a closed analytical form, which has the correct behaviour in various limiting cases. Numerical computations are used to investigate the effect of finite sample thickness in modifying the rotation and circular dichroism predicted from the infinite medium theory. This is of importance in interpreting the results of experiments.