Diffraction Analysis for Blackbody Calibrations

Realistic blackbody calibrations in low-background infrared chambers involve multiple optical elements that affect radiometric throughput by diffraction at aperture and baffle perimeters. There are many aspects to the problem, including (1.) developing efficient numerical algorithms that describe wave propagation, (2.) identification of important/ unimportant optical elements and subsystems that affect results, (3.) classifying results in terms of first- and secondorder contributions to diffraction corrections on measurements, (4.) integrating results for spectral throughput over the Planck spectrum (or other weighting function) to determine outcomes of total-power measurements. Progress in all of the above has been achieved in the past, and recent innovations in synthesizing all of the above results more quantitatively greatly improve turnaround times and quality-control for practical calibrations. The role of partial coherence effects, in particular, has witnessed considerable advance.