State of the art on macroscopic models for the determination of thin films optical properties

Optical properties (i.e. reflectance, transmittance, etc) of light scattering materials can be described using two approaches.The first approach, models the interaction of light with the matters particles (microscopic approach), while the second, models the light fluxes into and out of bulked considered matter (macroscopic approach). Kubelka-Munk (K-M) is the most common theory of macroscopic modeling, for calculating the change of light fluxes (two-flux theory) as a function of scattering, absorption, and distance. Modified K-M Models, for calculating the optical properties of rough surfaces, revisedK-M theories as well as, inversion methods from KM analysis are presented. A K-M and Mie microscopicmodel is used for emmitance calculations of coating layers. Three flux models track two diffuse fluxes and one collimated flux, while four flux models track two diffuse and two collimated fluxes. Maheu-Letoulouzan-Gouesbet (M-L-G), multilayered, and other generalized four-flux models are shown. A number of applications of the discussed models in pigments (such us polymer coatings), light scattering from TiO2 and red particles are also presented.