Direct measurement of the two principal refractive indexes of a nematic liquid crystal slab.

A new technique to measure the principal refractive indexes of a nematic liquid crystal is presented. The method is based on an indirect measurement of the refraction angle by determining the direction of a magnetic field which minimizes the light scattering. With this technique one can perform different light scattering experiments, which require a knowledge of the refractive indexes, on the same crystal slab.

A sensitive half-shadow ellipsometer.

The ellipsometer described herein uses a He-Ne laser as monochromatic light source, and, in the analysis system, a sensitive elliptic detector namely the Bravais-Zakrzewski-Perucca biplate. The use of this biplate allows better accuracy in measurements. Furthermore, a method of measuring and evaluating the results is described which includes, but is not limited to, conventional methods.