Involvement of scattered UV light in the generation of photoluminescence in powdered phosphor screens

In powdered phosphor screens, a large fraction of incident UV light is refl ected from the surface of individual particles, with the remainder penetrat ing the phosphor surface to generate photoluminescence. The reflected UV ph otons entering the screen are randomly scattered throughout the particulate structure, resulting in photoluminescence down to, for example, 10 layers deep from the surface. An optimum number of layers within a screen for lumi nance in reflection and transmission modes can be calculated after determin ation of the absorption and scattering coefficients per layer in a practica l phosphor screen. Good agreement has been obtained between the calculated and experimental results.