NEARLY PERFECT MULTILAYER DIELECTRIC REFLECTORS - THEORY

Reflectance, absorptance, and phase distortion of highly reflecting dielectric mirrors subject to small deviations from normal incidence, optimum wavelength λ, and layer thickness d and index n are derived by matrix methods carried to first order in the absorption and second order in other parameters.Only small errors in absorptance or reflectance are made by oblique incidence measurements or by changes in λ, n, or d, typical errors in A[˜θ2, (Δλ)2, (Δn)2, (Δd)2] being 1% for θ = 5.8° or 4.5% for a 5% change in λ,n, or d.Phase distortions ϕr also are small, typically 0.01 rad for either θ ≃ 7° or a 0.3% change in λ, n, or d.© 1979 Optical Society of America.