Diffraction and Polarization Effects in Radiation Heat Transfer: A Case Study

The Monte-Carlo ray-trace (MCRT) method is particularly well suited to the optical design of instrumentation in which very small radiant signals must be separated from a strong background. The present contribution explores an important application lying at the intersection of physical optics and radiation heat transfer. Specifically, we consider instruments intended to monitor the planetary energy budget from low earth orbit. To accommodate the increasingly exigent accuracy requirements imposed by the Earth science community, it has become necessary to include effects such as diffraction and polarization that are normally omitted in traditional radiation heat transfer modeling. This requires that the usual concept of a “ray” be extended to include wavelength, a phase angle, and polarization. A realistic instrument concept is considered that fully exercises the ability of such an approach to capture optical effects that are either ignored or assessed “offline” in traditional modeling efforts. Investigated is the range of variation of detector illumination when the effects of the source spectral content, diffraction, and polarization are included.