High-reflection multilayer for wavelength range of 200–30 nm

Composite multilayers consisting of a top single layer and piled double layers with high reflectance through a 200–30 nm wavelength range have been designed and fabricated for normal incidence optical systems and the performance was checked in a 140–30 nm range. The normal incidence reflectance of SiC (top layer)–Y2O3/Mg (double layers) multilayer was more than 14% in a range of 40–30 nm which is much higher than those of W, and 20–40% above 50 nm which is comparable with that of W. The reflectance of SiC (top layer)–Mg/SiC (double layers) multilayer was a little lower than those values.