Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5427610 | Journal of Quantitative Spectroscopy and Radiative Transfer | 2016 | 10 Pages |
â¢We measure light scattering from mixtures of dark and bright powders.â¢Dark volcanic sand and bright salt or ferric sulfate are studied.â¢Negative linear polarization changes monotonically with mixing volume ratio.â¢High-contrast mixtures obey the Umov law.
We experimentally study light scattering by particulate surfaces consisting of two high-contrast materials. Using the Finnish Geodetic Institute field goniospectropolarimeter, reflectance and degree of linear polarization are measured in dark volcanic sand, bright salt (NaCl) and bright ferric sulfate (Fe2(SO4)3); and in mixtures of bright and dark components. We found that the light-scattering response monotonically changes with volume ratio of dark and bright components. In contrast to previous finding, we do not detect an enhancement of the negative polarization amplitude in two-component high-contrast mixtures. Two-component mixtures reveal an inverse correlation between maximum of their linear polarization and reflectance near backscattering, the so-called Umov effect. In log-log scales this inverse correlation takes a linear form for the dark and moderate-dark samples, while for the brightest samples there is a noticeable deviation from the linear trend.