Polarization characteristics of Spectralon illuminated by coherent light
The Multi-angle Imaging SpectroRadiometer (MISR) makes use of an on-board calibration system to provide routine absolute radiometric calibrations of the instrument while in flight. In addition to on-board detector standards, two Spectralon panels will reflect sunlight into the nine cameras. Prior to assembling the instrument, these panels were quantified in terms of their bidirectional reflectance distribution function (BRDF). Included in the testing were principal-plane measurements where
... urements where polarizations of the source and detector were analyzed. The BRDF was measured as a function of the detector angle over an elevation range of 0"to S o , in 5" increments, as referenced from the panel normal. This was done at laser wavelengths of 442.0,632.8, and 859.9 nm. The BRDF was found to increase in the forward direction, at all wavelengths, for both an increasing angle of incidence and angle of reflection. This forward-scattering effect is greater for the incident perpendicular, spolarization state than for the parallel, p-polarization state. Conversely, the incident parallel ,state has a larger BRDF than the perpendicular polarization state at the larger backward scattering angles.The fraction of polarization is reported here for these cases.