SPECTRAL RAY TRACING FROM NEAR FIELD GONIOPHOTOMETER MEASUREMENTS

Measured light source models have been widely used in ray trace simulations for optical design for more than 15 years now, but to date the generated ray sets have not contained spectral information. In some limited cases, tristimulus measurements can be helpful, but most ray tracing software requires a specific wavelength assigned to each ray to enable full color simulations of an optical system. This paper describes and tests various techniques for combining spectral measurements with either photopic or tristimulus imaging colorimeters to produce ray sets that contain a wavelength. These ray sets can generally be readily used by most ray-tracing software to more accurately refract and diffract rays through the optical system and to generate illuminance or luminance distributions that also include colorimetric information. Finally the methods are tested with real light sources where spectral power distribution varies significantly spatially across the light source and/or as a function of angle.