Diffraction of light by a slit in anisotropic media with closed and open wave vector surface

Fraunhofer diffraction of an electromagnetic wave by a slit on an opaque screen located between vacuum and an anisotropic medium with closed and open wave vectors surface is considered. A formula for diffraction in a material medium is obtained, including the case of diffraction into a uniaxial anisotropic medium in the absence of absorption, and the formation of diffraction minima and maxima is studied.