A Geometrical Optics Approximation for Refraction at a Planar Interface between Arbitrarily Lossy Media

Abstract

A general geometrical optics formulation is derived for refraction at a planar interface between arbitrarily lossy media. Using a Fourier transform technique, we determine the exact field in one medium due to a point source in another. A high-frequency asymptotic solution is found involving complex ray angles and a complex refraction point on the interface. This solution and two other ray formations used by other researchers for the same problem are compared against a numerical evaluation of the exact field expression. The solution with the complex refraction point gives the most generally useful results.