A focusing multilayer analyser for local diffraction studies

• Published in: Journal of synchrotron radiation 1999-09, Vol.6 (5), p.979-984
• Main Authors: Lienert, U., Poulsen, H. F., Honkimäki, V., Schulze, C., Hignette, O.
• Format: Article
• Language: English
• Subjects: lattice strains; X-ray optics
• ISSN: 1600-5775; 0909-0495; 1600-5775
• DOI: 10.1107/S0909049599001934

A novel X‐ray diffraction technique for the local structural characterization of thick specimens is presented. Broad energy‐band focusing elements are used both on the incoming and exit (diffracted) side of the sample. The geometry allows imaging, and magnification, of a line through the thickness of the sample. In comparison with conventional methods of defining three‐dimensional gauge volumes the new technique provides superior depth resolution, higher flux, and a remedy for some systematic errors occurring in strain measurements due to, for example, grain size effects. The technique is validated by a synchrotron test experiment using a bent and meridionally graded multilayer as the focusing analyser element. The incoming beam is monochromated, at 30 keV, and focused to a 15 µm spot size by means of a bent Laue crystal. The resulting depth profile from the (222) reflection of a 21 µm‐thick rolled Au foil has a width of 44 µm. The depth resolution, magnification and reflectivity as a function of the energy bandwidth are found to be well matched by theory. The prospect of the technique and the associated aberrations are discussed.