The Physics of X-Ray Multilayer Structures

The development of multilayer coatings for soft x-ray optics has matured in the last decade, resulting in numerous applications in many fields including x-ray astronomy, x-ray microscopy, x-ray lasers, and projection lithography. High performance multilayer-coated optics have been realized for normal incidence applications at wavelengths longer than the silicon absorption edge near 124 Å and for grazing incidence applications at shorter wavelengths, yet the challenge remains to develop high-reflectance normal incidence coatings above the silicon edge.