Abstract

The recent successes in producing multilayers as reflecting coatings on mirrors for the VUV and soft-x-ray regions has prompted an investigation of their applicability to diffraction gratings. If the grating is to be used at near-normal incidence, matching the coating to the grating is a simple problem. If, however, the grating is to be used at oblique incidence, the matching technique must take into consideration the fact that the grating obeys the simple Bragg law, but the coating follows the corrected Bragg law. Furthermore, even if grating and coating are properly matched for use at grazing incidence there remains the problem of contamination of the spectrum by radiation from "suborders" and longer-wavelength spectral regions, where the outermost layers of the multilayer have a high reflectance. Successful coatings have been produced for both laminar and blazed gratings. Examples will be given of the matching procedure, and calculations and measurements will be presented showing the dramatic increase in efficiency as well as the presence of longer-wavelength radiation.

© 1990 Optical Society of America