Proceedings Article | 20 August 2008
Proc. SPIE. 7081, Earth Observing Systems XIII
KEYWORDS: Sensors, Calibration, Satellites, Remote sensing, Light scattering, Reflectivity, Vegetation, Bidirectional reflectance transmission function, Diffusers, Systems modeling
Satellite instruments operating in the reflective solar wavelength region often require accurate and precise
determination of the Bidirectional Reflectance Distribution Function (BRDF) of laboratory based diffusers used in their
pre-flight calibrations. In this paper we present gray Spectralon BRDF measured using a monochromatic broadband
source at ultraviolet, visible and near-infrared wavelengths. By comparing these results, we quantitatively examine the
wavelength and geometrical scatter properties of gray-scale Spectralon. The Spectralon diffusers with specified
hemispherical reflectances of 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 99% were measured using P
and S incident polarized light over a range of incident and scatter angles. The measurements are compared, and the
influence of material composition on the BRDF is described. The future application of gray-scale Spectralon in the
calibration of spaceborne sensors is described. All data were obtained using the out-of-plane scatterometer located in
NASA's Goddard Space Flight Center's Diffuser Calibration Facility. The results are NIST traceable.
