Ray techniques in electromagnetics

The principles of ray optics and, in more detail, some selected applications of ray techniques to electromagnetics are reviewed briefly. It is shown how a systematic use of matrix representation for the wavefront curvature and for its transformations simplify the handling of arbitrary pencils of rays and, consequently, the field computations. The same methods apply to complex rays which give a means of describing the effects of reflections and refractions on Gaussian beams. The relations of ray optics to other disciplines are also briefly discussed.