Multilayer optics and applications in EUV and x-ray region

Abstract

For extreme ultraviolet (EUV) radiation and soft X-rays, real part of the refractive indices of all materials are very close to unity, coupled with high absorption, makes the realization of high-reflective mirrors (just like visible and infrared light) impossible. Multilayer is a nano-structure, alternating of low- and high-Z materials in a periodic way, which can greatly enhance the reflectivity via the interference of light reflected from interfaces, like crystal optics. Reflective mirrors, polarization elements, monochromators, etc, can be made basing on multi-layer structures. Zone plate is a powerful tool to focus the light beam for EUV and soft X-ray into nanometer scale, which is produced by electron beam etching method. However, for hard X-ray, the zone plate will has smaller width of outmost layer and larger aspect ratio, which is difficult to realize. Multilayer Laue lens (MLL) is a promising method to overcome these limitations. MLL is a novel linear zone plate which is produced by depositing the depth-graded multilayer, according to the zone plate law reversely, on flat substrate and then slicing and polishing it to an ideal aspect ratio. In this paper, some recent development of multilayer optics for EUV and X-ray regions in IPOE will be introduced.