Specific characteristics of the configurations of optical axes in absorptive crystals

Abstract

The spherical coordinates of four optical axes in absorptive orthorhombic crystals have been determined in terms of the components of the tensor of inverse permittivity constant $\hat B = \hat \varepsilon ^{ - 1}$. The evolution of the configurations of these four vectors has been studied as a function of the complex tensor. It was shown that anomalous changes in the angles formed by the optical axes and the orientations of the planes in which these vectors are located occur if the parameters of dielectric anisotropy of the crystal are comparable with the absorption level. In particular, these dramatic changes can be seen in the description of the optical-axis splitting in absorptive uniaxial crystals caused by “ inclusion” into consideration of feeble orthorhombic anisotropy. In these cases, the slight absorption anisotropy considerably influences the configurations that cannot be reduced to small corrections.