An experimental investigation of the depolarization characteristics of complex surfaces illuminated by 6328-Å laser radiation was made on a large scale polarimeter. Measurements were made on specimens such as basalt, limonite, volcanic ash, wet and dry sand, gravel, silt, and foliage in various states of freshness. (For powders and aggregates, depolarization appears more pronounced as the size of the individual particles decreases, and as the roughness and porosity of the surface features increases, whereas depolarization appears less pronounced as water is adsorbed or absorbed.) The depolarization signature of foliage served to characterize a particular species, and dryness of the specimens tended to increase the depolarization. As a practical outcome, it appears that additional surface characterization or signature can be obtained through measurement of depolarization characteristics.
W. G. Egan, J. Grusauskas, and H. B. Hallock, "Optical Depolarization Properties of Surfaces Illuminated by Coherent Light," Appl. Opt. 7, 1529-1534 (1968)