Directional emittance of a two-dimensional scattering medium with Fresnel boundaries

The influences of the refractive index, scattering albedo, and optical sizes on the thermal radiation in a two-dimensional rectangular, isotropically scattering medium bounded by opically smooth boundaries having Fresnel reflection are considered. The complexity of formulation resulting from this specular resulting from this specular reflection is reduced by treating the images as effective media and by neglecting the radiation from faraway images. The problem can then be described by an integral equation (the source function) that is solved iteratively here; the method is then applied to study the directional emittance of a two- dimensional semi-infinite slab. Results show that the directional emittance is aximuthally dependent for the rectangular geometries, that the effects of the relative refractive index on the emittance depend significantly on the albedo, and that Fresnel reflection generally decreases the angular dependence of the emittance compared to free boundaries. (Author)