The reflection efficiency of a lightly ruled glass grating, mainly in relation to its short-wavelength limit in the soft x-ray region, is discussed on the basis of the Rayleigh-Fano theory, which deals with Wood’s anomalies of optical gratings. The reflectances of waves diffracted by a glass grating are calculated under appropriately assumed conditions and the locations of the abrupt enhancement of reflection are derived. Theoretical predictions have been confirmed by a simulated experiment performed in the visible region.
SHIRO FUJIWARA and YASUO IGUCHI, "Reflection Efficiencies of Grating in the Soft X-Ray Region," J. Opt. Soc. Am. 58, 1189-1191 (1968)