Interior and exterior daylight illuminants for the colorimetry of fluorescent materials

Abstract

The difficulties in simulating CIE Standard Illuminant D65 are considered and an interior daylight illuminant is described, Illuminant ID65, representing exterior daylight attenuated by average window glass. The benefits of Illuminant ID65 are that it represents the daylight source which most commonly occurs in the viewing of critically coloured merchandise, and that it can be practically simulated using a filtered tungsten‐halogen source. Its applicability to measurements, particularly to the assessment of fluorescent samples, is considered. The results of measurements on the two common classes of fluorescent samples are discussed and indicate that an Illuminant ID65 simulator can be used validly for the measurement of fluorescent materials, even including materials intended specifically for exterior use.