Modeling the optical properties of fluorescent powders: Y1.91Eu0.09O3

A numerical model is developed to study the optical properties of phosphor powder coatings. The method derived uses a combination of ray tracing and M onte Carlo modeling which allows us to calculate the absorption, reflection , and transmission for the exciting ultraviolet radiation as well as for th e emitted visible light. Size, shape, morphology, density of packing of the phosphor grains, and the roughness of the coating can be studied in detail with our model. Calculations for Y1.91Eu0.09O3 red phosphor powder layers used in commercial fluorescent lamps are presented. Good agreement with exp eriment was found. (C) 1999 American Institute of Physics. [S0021-8979(99)0 3801-3].