Optical studies of liquid crystals

Ellipsometry is well known as an optical technique for investigating the dielectric properties of thin films. Its evolution into spectroscopic and also variable-angle ellipsometry allowed the use of this technique also to anisotropic materials, like liquid crystals. In this work we present an overview on the ellipsometric studies on nematic liquid crystals characterization and reorientation. The former can be realized with simple reflection measurements: anisotropic refractive indices measurements are presented in the visible and near-infrared wavelength ranges. Moreover, with a temperature control, the nematic-isotropic transition can be measured. The latter, the molecular director distribution, can be measured with a more complex procedure that allows us to measure the values of pretilt and anchoring strength.