Application of generalized ellipsometry to anisotropic crystals*

The technique of generalized ellipsometry is briefly reviewed. An improved criterion for computing the normalized 2 × 2 complex reflection matrix of an anisotropic surface from multiple-null ellipsometer measurements (in excess of three) is given. Generalized ellipsometry, together with the recently developed 4 × 4-matrix methods for the study of the reflection and transmission of polarized light by stratified anisotropic media, provide the basic tools to carry out and to interpret ellipsometric measurements on anisotropic structures. As an example, the case of uniaxial (absorbing) crystals, with the optic axis parallel to the surface, is considered. From three or more null measurements at a single unknown orientation of the optic axis, the five parameters (the ordinary and extraordinary complex indices of refraction and the angle of inclination of the optic axis from the plane of incidence) that characterize a uniaxial crystal of calcite are all determined.