We discovered a theoretical link between the reflectivity of a solid surface and the resulting polarization, and we want to exploit this finding to advance the state-of-the-art of polarimetric remote sensing. At a special geometry, a spectral plot of polarization versus reflectivity collapses into a 1-dimensional degenerate curve (termed the U-curve) that applies to all materials, both conductors and dielectrics. The U-curve shows an inverse relationship between polarization and reflectivity and provides a new theoretical underpinning to explain why dark objects are more polarizing than brighter ones.1-7 We argue that the U-curve represents the Polarization Relative to the Maximum Attainable (PReMA) for a surface of given reflectivity. We claim that standard polarization metrics (e.g., DoLP) are biased because most surfaces cannot polarize reflected light at the 100% level, and therefore, by using PReMA as a constraint for normalization, we can create a new polarization metric that should be superior to old ones. Because the U-curve applies to perfectly smooth dielectric materials, in theory, polarimetric measurements at this special geometry could be used to optically quantify the surface roughness of a material. Also, we propose that the PReMA method could provide the basis for a new, bi-static radar observation scenario to provide more quantitative information about the earth’s surface.
|