FEASIBILITY OF TiO2 PIGMENTED POLYMER FILMS AS LIGHT DIFFUSING MATERIALS IN DAYLIGHTING APPLICATIONS

Light diffusers for daylighting applications should have a substantial diffuse transmittance with the forward scattered light distributed as isotropically as possible. We consider the possibility of using pigmented polymer foils for this purpose and propose a method for their theoretical optimization. The amount of electromagnetic energy transmitted through a particulate film illuminated with unpolarized radiation is modeled, by solving within the far-field approximation the radiative transfer equation for successive scattering orders, accounting for boundary reflections at film interfaces. The angular dependence of transmitted diffuse intensity patterns is displayed for titanium dioxide pigmented films. Conditions for having transmitted diffuse intensity patterns of visible radiation, characterized by significant amounts of energy laterally scattered, are established by varying the mean size and concentration of the particles, as well as the thickness of the film.