Relationship Between And Measurement Of Differential Scattering Coefficient (σ°) And Bidirectional Reflectance Distribution Function (Brdf)

The physical mechanism of scattering of electromagnetic beams from a surface can be quantified by either differential scattering coefficient (0- ) or bidirectional reflectance distribution function (BRDF). The differential scattering coefficient is an extension of radar scattering cross section of targets, and the geometrical constraints inferred in its measurement at microwave frequencies are relatively easily satisfied. These same con-straints must also be met in the measurement of BRDF using coherent optical frequency beams and these may influence the geometrical configuration to obtain range-independent values. For a diffuse surface, u = 47BRDF cos G. cos Gr where and Gr are the incidence and reflected angles, respectively, from surface normal. Considerably more care in the design of the configuration is required for the measurement of surfaces entailing specular components than for diffuse surfaces.