Illumination system tolerancing

Tolerancing of illumination systems is currently a difficult task, especially for components that are injection molded. The ISO standards are not applicable to such systems due to their innate requirements of image formation. Methods to parameterize the shape of injection-molded optical components are presented. First, a method based on experimental measurement of actual components is presented. Next, this method is extended to the Monte Carlo formation of perturbed parts based upon these measurements. Finally, a method based on the application of a bi-directional surface distribution function (BSDF), i.e., scatter profile, is based upon ray-trace results from the application of the experimental measurements. The BSDF method is fit with the ABg scatter function, applied to witness sample surfaces, and compared to the perturbation method. The utility of these two methods is presented, whereby the BSDF method is appropriate for systems with many ray-surface interactions, while the perturbation method is best suited for systems with limited ray-surface interactions.