Optical EngineeringPrincipal Mueller matrix of reflection and scattering measured for a one-dimensional rough surface
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Reflectance R, ellipsometric parameters (?,?), depolarizations D, and cross-polarized depolarization Dv of specular reflection, and scattering by a rough stainless steel surface are measured using a null ellipsometer. The three polarization elements (Px ,Py ,Pz ) of a principal Mueller matrix are obtained from D, ?, and ?. The measured ? and ? of specular reflection for incident angle ?>70 deg are fit to the Fresnel equations to obtain n and k. The measured specular R(? ) is fit to Beckmann’s scattering theory to obtain the root mean square (rms) roughness ?. The fit ? (= 392 nm) is of the same order as the stylus measured ? (= 484 nm). The D of specular reflection is small (< 0.07). Scattering measurements are made with variable sample orientation at a detection direction 40 deg backward from the incident direction. The Dv of scattering is very small (< 0.002). The values of ?, ?, Px , Pz , and Dv of scattering are about constant for an off-specular angle (OSA) within ±60 deg and can be explained by the facet model with single scattering. The measured bidirectional reflectance distribution function (BRDF) in this region can be converted to slope angle distribution with OSA52 slope angle. The values of ?, ?, Px , Pz , and Dv of scattering deviate significantly and symmetrically from a constant level for |OSA|> 60 deg, for which the simple facet model with single scattering does not apply.