Measurements of the normal-incidence X-ray reflectance of a molybdenum-silicon multilayer deposited on a 2000 l/mm grating

Normal-incidence grating optics coated with appropriate multilayers show great promise as a means of achieving high spectral resolution at X-ray wavelengths. Multilayer-coated mirrors have been made and tested successfully, but comparatively little work on such multilayer-coated gratings has been reported. We describe the results of reflectance measurements made on a superpolished flat mirror and a Ferranti-Astron ion-etched 2000 l/mm laminar grating, which were coated simultaneously at the Lawrence Livermore National Laboratory with a 25-period Mo-Si multilayer. The multilayer was designed so that at normal incidence the mirror would have a maximum reflectance of 31% at a wavelength of 176 A. The measurements were performed using a reflectometer and monochromator installed on the Naval Research Laboratory X24C beamline at the Brookhaven National Synchrotron Light Source. (orig.)