Proceedings PaperScattering Of Baffle Vane Edges
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Rejection of off-axis stray radiation by efficient baffling continues to be a major problem in designing low background, wide field of view infrared sensors. For an efficiently baffled sensor, direct scattering from baffle vane edges becomes the dominant contributor to stray radiation. Existing computer programs for stray radiation analysis assume ideal baffle vane edges and do not account for the scattering effects of actual baffle vane edges due to the uncontrollable edge geometry. We propose a baffle vane edge model based on empirical data; this model is described by an edge scatter distribution function (ESDF) which quantifies the scattering effect of actual baffle vane edges in the same manner as a bidirectional reflectance distribution function (BRDF) quantifies scattering surfaces. The ESDF consists of three physical processes: 1) scattering of the beveled surface of a baffle vane edge, 2) diffraction of an ideal knife edge, and 3) diffused reflectance of an actual baffle vane edge. This empirical edge model has been incorporated into an existing stray radiation analysis computer program. Theory and measured data are compared.