IR optical scattering instrument with out-of-plane and retro-reflection capabilities

An infrared (IR) optical scattering instrument for BRDF measurement has been developed at NIST with out-of-plane and retro-reflection capabilities. In this paper, a description of the BRDF instrument, its use of multi-wavelength sources (785 nm-10.6 /spl mu/m) and a retro-reflection measurement capability, and alignment techniques using a quadrant detector are presented. The related alignment results for the in- and out-of-plane geometries and reflectance of a gold mirror versus incident angle are also reported. The results of BRDF measurements for a concentric groove graphite radiator in the retro-reflection configuration are demonstrated.