Computer analysis is quickly becoming the most important tool in the design of thick waveguide illumination systems used in car radios and dashboards. Used correctly, computer modeling decreases waveguide design time and increases cost effectiveness. This paper presents examples of computer analysis. First, modeled sources such as tungsten filaments and miniature booted bulbs are presented. Computer simulation of thick optical waveguides illuminated with these sources will then demonstrate the correlation between experimental measurement and computer model output. Output coupling is also modeled and the results provide information about the amount, uniformity, and directionality of the output flux. All of this information is of the utmost importance to an illumination system designer.