Multilayer mirror for reflecting radiation at a preselected wavelength.

摘要

A high reflectance mirror (30) utilizing a dielectric stack (32) having multiple layers of low (2,4,6...32L) and high (1,3,7...33H) refractive index material at least one of which is absorbing atthe design wavelength. At least one pair of layers is formed on a substructure (31) with the thickness of the individual layers being both different from a quarterwave optical thickness and preselected to maximize the reflectance of the mirror. Mirrors in which both dielectric materials in the stack have different absorptances at the design wavelength are disclosed with the layer thicknesses of one or more optimum pairs formed on a substructure being different from a quarterwave optical thickness such that the layers of higher absorptance material are less than a quarterwave optical thickness and the layers of lower absorptance material are more than a quarterwave optical thickness. The individual thicknesses of the layers are optimized to provide maximum reflectance, leading to a nonperiodic stack when a substantial number of such optimum pairs of layers are utilized.