Gratings with Blaze Angles Down to 0.1° for Photon Energies up to 10 keV

Abstract

A new technique for the patterning of blazed gratings with extremely small blaze angles down to 0.1° is described. Mechanically ruled gratings are transferred from the gold ruling layer into the silicon substrate by reactive ionbeam etching. The primarily ruled blaze angle can be reduced by a factor of up to 28. The plane blaze facets are maintained during the etching process resulting in high blaze efficiency. The rms micro roughness on the blaze facets, that affects the efficiency as well as the diffuse straylight is reduced to below 0.2 nm by this technique. Groove profiles of such gratings with various groove densities and blaze angles measured by atomic force microscopy are presented. Calculated diffraction efficiency and resolving power and the impact of grating imperfections on the monochromator and spectrometer design are discussed [1] and [2]. Plane blazed gratings patterned by this technique were delivered to BESSY and to Sincrotrone Trieste. The results of efficiency measurements of these gratings are reported in [3] and [4].