We have deposited W/Si multilayer mirrors using magnetron sputtering, and m
easured their reflectivity at the Beijing Synchrotron Radiation Facility. T
he W/Si multilayer mirrors show a peak reflectivity of approximately 10% at
a photo-energy of 1200 eV and 10.5% at a photo-energy of 700 eV at an inci
dence angle of 81 degrees. So far, no higher reflectivity than that given i
n this letter has been reported.