The Pre-Transitional Effect in Antiferroelectric Liquid Crystals: A Comparison between Theory and Experiment

We have investigated, experimentally and theoretically, the low field (pre-transitional) behaviour of an AFLC material. By measuring the light transmission through a device between crossed polarizers, as a function of both orientation and applied voltage, we determine the variation of both the effective optic axis tilt angle ? and the optical anisotropy ?n as a function of voltage. In order to model this behaviour we use an order parameter theory based on changes to the distribution of molecules within the AFLC layers rather than the soft mode description. With this model we have been able to describe the observed tilt and anisotropy behaviour.