This paper describes a method for accurately and simply calculating the effective emissivity of a grooved surface, and analyses the uncertainties. Using this method, the directional and hemispheric emissivities of a grooved surface are calculated and the results dis-cussed. The method further permits an accurate determination of the normal and hemispheric emissivity of a cylindrically baffled grooved plate source.
"A Method For Calculating The Effective Emissivity Of A Groove Structure", Proc. SPIE 0810, Optical Systems for Space Applications, (18 September 1987); doi: 10.1117/12.941553; https://doi.org/10.1117/12.941553