Effects of aperture size on focusing of electromagnetic waves into a biaxial crystal

Recently exact integral representations suitable for studying electromagnetic waves that are focused through a plane interface into a biaxial crystal were derived along with representations valid for paraxial focusing geometries. Here we compare the two solutions for different aperture sizes in order to determine the range of validity of the paraxial approximation. Also, we study the relative contributions to the total intensity of the co-polarized, the cross-polarized, and the longitudinally-polarized intensities.