GRAZING-INCIDENCE EFFICIENCIES IN THE 28-42-ANGSTROM WAVELENGTH REGION OF REPLICAS OF THE SKYLAB 3600-LINE MM CONCAVE GRATING WITH MULTILAYER AND GOLD COATINGS/

The efficiencies of replicas of the Skylab 3600-line/mm concave gratin g with multilayer and gold coatings were measured by using synchrotron radiation at an angle of incidence of 79 degrees and in the 28-42-Ang strom wavelength range. The blaze angle of the grating facets that fac ed the incident radiation was 3.1 degrees, and the average angle of th e opposite facets was 6 degrees. For the gold grating, the -1 outside order had the highest efficiency of any diffracted order (excluding th e zero order) over the entire wavelength range. Calculations of the gr ating efficiency indicated that the high efficiency in the -1 order re sulted from the rather small angle (6 degrees) of the facets opposite the incident radiation. For the multilayer grating, the efficiency in the on-blaze +2 inside order was enhanced in the 30-34-Angstrom wavele ngth region as a result of the high reflectance of the multilayer coat ing. The maximum efficiency in the +2 order occurred at the wavelength (32 Angstrom) corresponding to the peak of the reflectance of the mul tilayer coating on the facets facing the incident radiation. These res ults further demonstrate that a multilayer coating can be used to enha nce the efficiency, in a selected wavelength range and in the on-blaze order, of a grating operating at a small grazing angle (11 degrees). (C) 1997 Optical Society of America.