Abstract

We have made absolute diffraction efficiency measurements of freestanding x-ray transmission gratings. The grating periods are 2000 and 3000 Å with a nominal line-to-space ratio of 1:1 and thickness from 4000 to 6000 Å. Although theoretical calculations of ideal grating performance are well established, actual physical parameters of these microstructures are not readily accessible. Accurate calibration of actual performance is critically needed to allow unfolding of multicomponent x-ray spectral data as the various dispersion orders overlap. Monochromatic line emission at C Kα, Cu Lα, and Al Kα were used. Diffraction lobes up to eighth order were observed. Significant changes in the diffraction efficiency of individual gratings occurred as the radiation wavelength was varied as a result of phase change of partially transmitted radiation. Some structural defects also caused energy dependent changes. The measurement apparatus consisted of a changeable anode Henke line source, Soller slit collimation, and an energy discriminating position sensitive proportional counter as a detector.

© 1985 Optical Society of America