Colorimetry and its accuracy in the measurement of fluorescent materials by the two‐monochromator method

The fundamental procedure involved in the two-monochromator method for determining the spectral radiance factors of fluorescent materials is described, and some measured results are presented. The colorimetric accuracy of the method was confirmed by comparing two sets of tristimulus values: (1) those based on the two-monochromator method and calculated from the reflected and the fluorescent spectral radiance factors and the spectral power distributions of a tungsten-halogen lamp and a xenon lamp (which were determined separately); and (2) those calculated from the total radiance factors obtained from the measurement under polychromatic illumination, where the fluorescent materials were irradiated with the tungsten and the xenon lamp. The color differences between these sets of tristimulus values in CIE-LUV color space were estimated to be less than 1.0 unit, irrespective of the illuminant or the source.