Metallic crossed gratings

Abstract

Outlines the improvements to the transformation formalism for solving the diffraction problem for doubly-periodic roughened surfaces which have enabled the authors to treat accurately gratings whose depth ranges up to their period. The authors use the formalism to study the improvements in solar absorptivity consequent upon roughening both copper and nickel surfaces. Although the studies are limited to insufficiently-large groove depths, the authors, show that roughening can substantially improve absorptivity without significantly changing emissivity. The authors also show that the absorptivity of roughened surfaces can be less sensitive to the effects of non-zero angles of incidence than that of smooth surfaces.