REFLECTANCE OF A WIDE-BAND MULTILAYER X-RAY MIRROR AT NORMAL AND GRAZING INCIDENCES

The reflectance of a W-B4C multilayer mirror, with a period thickness that increased with depth into the multilayer, was measured at near-no rmal incidence with synchrotron radiation and at grazing incidence wit h Cu K alpha radiation. The period thickness increased linearly from 1 7.9 Angstrom at the top of the multilayer structure to 21.9 Angstrom a t the substrate while the same ratio of nodal layer to period thicknes s was maintained. For a grazing angle of 80 degrees (10 degrees from n ormal incidence), the peak reflectance was 1.1% at a wavelength of 36 Angstrom, and the reflectance profile was 1 Angstrom wide. For Cu K al pha radiation the reflectance peaked at a grazing angle of 2.4 degrees and was 0.4 degrees wide. Compared with a W-B4C multilayer mirror wit h a constant period thickness, the depth-graded multilayer mirror has wider reflectance profiles at near-normal and grazing incidences, resu lting in larger integrated reflectances and wider fields of view. (C) 1996 Optical Society of America