This paper discusses the reverse engineering of filament-based light sources for computerized optical analysis purposes, especially problems raised by source tolerances. The H12 automotive headlamp bulb is used as a case study. Notes on reverse engineering sources consist of: a statement of the challenges involved, our source-modeling methodology, and useful values and procedures pertaining to simulated sources and optical ray-tracing software. A multi-model approach is outlined and consists of: gathering tolerance information from specification sheets, modeling for source tolerances with eight key models, and output comparisons between nominal and “toleranced” versions of the H12 source. Recommendations for including source tolerances in non-imaging illumination designs conclude.
