An estimate for the minimum film thickness required to give the scattering
state of a reflective display material, such as a polymer dispersed liquid
crystal (PDLC) or polymer stabilized cholesteric texture (PSCT), a desired
diffuse luminous reflectance is presented. It is concluded that single scat
tering models are not suited for this task. To account for the multiple sca
ttering oi light, a previously developed model based on Mie scattering and
two-flux radiative transfer theory is implemented. This simple model relate
s the size, composition, and the volume fraction of the scattering entities
to the diffuse reflectance of the material. It is shown that the diffuse r
eflectance predictions from this model are in good agreement with measureme
nts from other turbid systems. Using assumptions intended to produce an und
erestimate, it is concluded that the most birefringent liquid crystal mater
ials currently available would require a film thickness between 11.5 mu m a
nd 17 mu m to give an ideal black substrate a diffuse luminous reflectance
of 60%.