Flux propagation in light pipe illumination systems

Abstract

An analytical model of light propagation in rectangular light pipes is presented. Light pipe illumination systems are an efficient means of collecting, transporting, and distributing light. One area where light pipe illumination systems are successfully employed is in transportation display lighting, such as instrument panel illumination. In these applications the transportation industry takes advantage of injection molding to manufacture light pipe systems at relatively low costs. One historical drawback to using light pipe illumination systems is the design effort associated with iterative prototyping cycles and evaluation. The model presented here is a graphical method of describing ray propagation in light pipes. The model describes ray direction vector space in spherical coordinates. With this model, the angular of a ray can be defined at any plane in the system. The angular mode propagation space describes input coupling, flux transport, and output coupling in light pipe illumination systems. The model of flux propagation described here is therefore a tool to aid in first order design and layout of light pipe illumination systems.