Spectral model of a fluorescent ink halftone

A model is presented of a fluorescent ink halftone. Unlike a nonfluorescent ink, which only absorbs, a fluorescent ink absorbs higher-energy photons a nd emits lower-energy photons. The amount of fluorescent light produced dep ends on the percent absorption of the incident light. For fluorescent ink p rinted on paper, both photon scattering within the paper substrate and mult iple internal reflections between the ink layer and the paper substrate sig nificantly increase the percent absorption, so a realistic model must inclu de these effects. The model presented here utilizes the generalized Clapper -Yule theory, which accounts for photon diffusion that is due to both scatt er and internal reflection. It is shown that while multiple internal reflec tions alone only marginally increase the percent absorption, when there are both scattering and internal reflection, the percent absorption is increas ed significantly. The current study is a theoretical model and does not pre sent experimental results. (C) 2000 Optical Society of America [S0740-3232( 00)00611-6].