Since a ray is, by definition, normal to the optical wavefront an understanding of the ray behavior makes it possible to trace the evolution of optical waves when they are passing through various optical elements. We find that the passage of a ray(or its reflection) through these elements can be described by simple 2x2 matrices Furthermore these matrices will be found to describe the propagation of spherical waves and of gaussian beams such as those which are characteristics of the output of lasers• Since a ray is, by definition, normal to the optical wavefront, an understanding of the ray behavior makes it possible to trace the evolution of optical waves when they are passing through various optical elements. We find that the passage of a ray (or its reflection) through these elements can be described by simple 2x2 matrices. Furthermore, these matrices will be found to describe the propagation of spherical waves and of Gaussian beams such as those which are characteristics of the output of lasers