Monte Carlo ray-tracing in particle-doped light guides

A general Monte Carlo ray-tracing method for light guides with particles randomly dispersed in a matrix material is presented. Previous ray-tracing approaches have been designed for undoped cylindrical light guides, where a propagating ray is deviated by total internal reflection only. These geometrical principles are extended and further developed into a method of ray-tracing suitable for particle-doped systems. Redefining ray direction after deviation by a particle, obtaining ray/wall intercept points and angles, and calculation of ray reflection angles from a cylindrical surface are described. Simulations of light from a source LED traced through TRIMM-doped (Transparent Refractive Index Matched Micro-Particle) polymethyl methacrylate (PMMA) light guides have been performed. Distributions of the light exiting the walls of two concentrations of TRIMM-doped light guides are given, as an example of an application of the described ray-tracing method.