Ray and Wave Propagation Through Optical Media

Before beginning a detailed discussion on optical resonators, which is to be the subject of the next Chapter, we introduce in this Chapter a few topics from geometrical and wave optics. The aim is to introduce some subjects that are not usually covered in elementary optics texts and that constitute a very useful background for the topics to be considered in next chapter. Thus, in particular, the matrix formulation of geometrical optics within the paraxial-ray approximation and wave propagation within the paraxial-wave approximation, leading to the ideas of Gaussian beam propagation, will be discussed here. Situations involving multiple interference such as in a multilayer dielectric coating or in a Fabry-Perot interferometer will also be considered.