Apparatus and methods for surficial milling of selected regions on surfaces of multilayer-film reflective mirrors as used in X-ray optical systems

摘要

Apparatus and methods are disclosed for milling selected regions on the surface of a multilayer-film reflective surface of an X-ray mirror with high accuracy and precision. The milling operation is performed to correct the reflected wavefront produced by the mirror, thereby producing a more uniform or otherwise more desirable phase distribution of the reflected wavefront. The milled multilayer films include multiple lamina sets each comprising respective layers of at least two respective substances. The layers usually are "stacked" in an alternating manner at a fixed period length on a mirror substrate. By selectively removing one or more surficial layers in selected locations, the methods and apparatus disclosed herein provide local corrections of the phase shift of the reflective wavefront. At each milling location on the multilayer-film surface, the depth profile can be stepwise or smoothly gradated. Milling methods can include lapping, ion-beam bombardment, plasma-enhanced chemical vapor machining (CVM), reactive-ion etching, photochemical reactions, or laser ablation.