Verfahren zur Reparatur eines mehrschichtigen optischen Elementes

摘要

The invention in one aspect involves a method for repairing an optical system. The optical system includes at least one optical element which comprises, in turn, a substrate (10) having a principal surface, and a multilayer coating (60) overlying the principal surface. The substrate comprises a first material, and the multilayer coating comprises plural second and at least third material layers (20, 30) in alternation. The method includes the steps of removing the multilayer coating from the substrate, and redepositing a new multilayer coating on the substrate. The old multilayer coating is removed in a single etching step while preserving the quality of the principal surface to such an extent that the peak reflectivity of the new multilayer coating is at least 80% the reflectivity of the old multilayer coating. In a second aspect, the invention involves a method for repairing an optical system of the kind described above, in which the optical element comprises a substrate having a principal surface, a layer of chromium overlying the principal surface, and a first layer of iridium overlying the chromium layer. The method comprises the steps of removing the first iridium layer from the substrate; and forming a second iridium coating on the substrate. The iridium layer is removed by exposing the iridium and chromium layers to an aqueous solution comprising potassium ferricyanide and sodium hydroxide, resulting in substantial dissolution of the chromium layer.