Numerical and experimental results for focusing of three-dimensional electromagnetic waves into uniaxial crystals.

We present experimental results for focusing of a three-dimensional electromagnetic wave through a plane interface into two different uniaxial crystals, a positive MgF2 crystal and a negative LiNbO3 crystal. These results are compared with numerical results and good agreement is found, both for intensity distributions in various receiving planes and for the locations of the sagittal and tangential focal planes. The theory is briefly outlined both for the exact solution, which includes extraparaxial geometries and double refraction, and for the paraxial solution, in which double refraction is ignored.