Infrared light scattering from surfaces covered with multiple dielectric overlayers

Abstract

Formulas are derived, using first-order perturbation theory, which predict light scattering from substrates coated with multiple dielectric overlayers. The scattering is assumed to result from surface irregularity. Numerical analysis is given for three types of dielectric stack configurations designed to typify experimental situations. The three configurations are substrate profile replicated at each dielectric interface, profile present at outermost dielectric layer only, and random roughness present at each interface. The formulas and configurations are used to model low efficiency rectangular groove gratings as beam sampling optical components and multilayer-overcoated metallic mirror substrates. Consideration is given to thermal expansion and fabrication error of thicknesses of the dielectric layers.