Ellipsometry Equation for the Structure Substrate–Uniaxial Anisotropic Film with the Optical Axis in the Plane of Incidence

A solution to the direct ellipsometry problem is presented for a single-layer model of an isotropic substrate–anisotropic film in the case of the orientation of the film optical axis in the plane of incidence. Analytical expressions for calculating the ellipsometric parameters of such a structure are obtained. A simple numerical algorithm is proposed for determining the ordinary ( \(n_{\textrm{o}}\) ) and extraordinary ( \(n_{\textrm{e}}\) ) refractive indices of a bulk crystal under various measurement conditions. The inverse problem of determining \(n_{\textrm{o}}\) , \(n_{\textrm{e}}\) , and the film thickness \(d\) when changing the azimuth of the optical axis is considered. The correlation of the required parameters for such a problem is discussed.