ABSTRACT
This chapter is based on some of the principles of nonimaging concentrator design, introduces the concepts that are fundamental to the design of the optical front end of a wireless infrared (IR) receiver. It describes the geometrical optics and ray tracing, Fermat’s principle and the Lagrange invariant, which is used to define the theoretical maximum limit of concentration. The chapter explains the edge ray principle and the concentration ratio. It also explains the design of thin-film optical filters and of some of the most common optical concentrators currently employed in wireless IR communication systems. The edge ray principle is a concept widely used in the design of some types on nonimaging concentrators. The concentration ratio is one of the most important parameters defining an optical concentrator. Geometrical optics is a helpful tool to represent a wave as a ray that denotes its direction of propagation.
