In several different research disciplines, modelling and simulating light propagation through volume scattering materials is a key necessity. Simulating diffusing and fluorescent materials in solid-state lighting and the interactions between intense light and skin tissue in biomedicine are just some examples of the widespread need for accurate volume scattering models. Although modelling volume scattering materials is important for several research fields, there is still no widespread reporting of model properties or of accurate and robust tools to estimate them, especially for lighting research. Most often, researchers estimate the scattering model properties, i.e. the absorption and scattering coefficients and the anisotropy factor, using Mie solutions. These are generally based on rough estimates of the scattering particle’s properties and assume that the particle is perfectly spherical or cylindrical. This approach is not well suited for the myriad of volume scattering materials available for illumination research. Our work uses the intensity-based inverse adding-doubling (i-IAD) method to estimate the volume scattering model properties of samples. In this work, we investigate the feasibility of this method in an experimental scenario by studying samples made with two different scattering particles embedded in a transparent polymer with different scattering particle concentrations and sample geometries. The light scattered by the samples is measured and their volume scattering properties estimated with i-IAD. We show the accuracy and robustness of i-IAD by extrapolating the scattering parameters obtained for low concentration samples to higher concentrations and comparing simulations with experiments for these higher concentrations. Furthermore, measurements of samples that contain both types of scattering particles were also accurately simulated using the model parameters estimated from low concentration samples. This work demonstrates that the intensity-based inverse adding-doubling method provides accurate estimates for the volume scattering model parameters and that they can be generalized for different concentrations, geometries and scattering particle mixtures.

Date Published: 21 June 2019
PDF: 10 pages
Proc. SPIE 11057, Modeling Aspects in Optical Metrology VII, 110570N (21 June 2019); doi: 10.1117/12.2525791

Published in SPIE Proceedings Vol. 11057:
Modeling Aspects in Optical Metrology VII
Bernd Bodermann; Karsten Frenner; Richard M. Silver, Editor(s)