Light Refraction by a Cholesteric Prism

Light propagation in a cholesteric medium has been completely discussed by de Vries [2]. The main results are that, for a given frequency, there are two eigenvibrations with quasi-circular polarizations, except i) for high frequencies and ii) near the reflection band (for the vibration having total reflection), where the polarization is linear. Looking at light refracted by a cholesteric prism, we have found i) that there were four refracted beams for high frequencies and ii) that for any frequency the refracted beams had a circular polarization. Refraction of light by an oblique interface is discussed and we show that for any frequency except in the reflection band there are four circularly polarized refracted beams (and also four reflected beams). The relative intensities of refracted and reflected beams are given, and an anomaly is predicted near the reflection band for the vibration having not total reflection.