Measurement of soft x-ray multilayer mirror reflectance at normal incidence using laser-produced plasmas

Abstract

We have used laser-produced plasmas as a broadband source of soft x rays to measure the normal incidence reflectance of multilayer mirrors in the 10–25 nm spectral region. The measurements have a spectral resolution of 0.03 nm and a reflectance resolution of 10%. Measurements made on a Mo/Si multilayer show excellent agreement with results obtained using a synchrotron and indicate a normal incidence peak reflectance of over 50% at 15 nm. By repeating the reflectance measurement at different positions across a single 7.5 cm mirror we determined multilayer uniformity as a function of position and we relate this dependence to the geometry of the deposition process.