Process - Induced inhomogeneities in higher asymmetry angle X-ray monochromators

Beam inhomogeneities of asymmetric Ge(220)-based V-shaped and single bounce monochromators have been studied both in metrological and imaging applications for photon energies around 8 keV. Presence of growth striations in graded GeSi, grains in single Cu crystal, and strains in thermally tuned V-channel monochromators observed in X-ray topographs excludes these materials from imaging applications. As for stochastic surface processing, chemomechanical polishing (CMP) produces better surface homogeneity than chemical polish. However, CMP is more difficult to be applied in V-channels, where chemical polishing is prefered. For comparison, measurements on surfaces processed by a deterministic mechanical method of single point diamond turning (SPDT) have shown SPDT to be a perspective technology. Again, to prepare deep grooves with this technique is also a challenge, mainly for tool makers. Some process induced features are observed as wavefield distortions in interference fringes. © 2013 SPIE.