SOFT-X-RAY MULTILAYER BEAM-SPLITTERS

A semitransparent Mo/Si multilayer beam splitter with a completely sel f-standing active area (10 x 10 mm) and a flatness of 1.1 nm (r.m.s) w as fabricated. The influence of the roughness of the membrane substrat e on the reflectivity of a beam splitter was investigated for differen t materials and deposition schemes. Precise control of multilayer stre ss to give a slightly tensile state not only enables the fabrication o f a large and flat reflection surface, but also makes it possible to e tch away the supporting membrane and obtain a completely self-standing structure. The performance evaluation using synchrotron radiation rev ealed that the fabricated beam splitter works as a one-to-one beam spl itter whose reflectivity and transmittance are both 27% (s-polarizatio n, 45 degrees, lambda = 13.4 mm).