Although the bottom diffuser film is one of the key components in the backlight unit in a liquid crystal display, the design equations for the optical performance of the bottom diffuser films were not reported in the literature. In this work, different narrow-size-distributed acrylic-styrene resin particles were mixed with the thermosetting acrylic resins and coated on the transparent poly(ethylene terephthalate) (PET) substrates to form particle-diffusing bottom diffusers with different optical performances. The correlations for the light transmittance and haze of a bottom diffuser as functions of the coating thickness/particle diameter ratio and beads/resin weight ratio were empirically developed as a power law model and an exponential model, respectively. The developed correlations may effectively reduce the time required for bottom diffuser designs in the backlight unit. (c) 2008 Elsevier B.V. All rights reserved.