An equation is derived from which the fluorescence obtained from a fluorescent whitener on a given substrate can be calculated from several reflectivity measurements. By use of this equation, one can explain theoretically and quantitatively such effects as the shape of the fluorescence vs concentration curve, the effect of the color of the substrate on fluorescence, the effect of the thickness or opacity of the substrate on fluorescence, and the effect of concentration of whitener on the shape of the emission curve.
EUGENE ALLEN, "Fluorescent White Dyes: Calculation of Fluorescence from Reflectivity Values," J. Opt. Soc. Am. 54, 506-514 (1964)