We demonstrate depth-resolved materials characterization by scanning a sample through an annular beam of X-rays. We measure Bragg X-ray diffraction from a sample with a planar detector positioned centrally in a circular dark field defined by the annular beam. The diffraction maxima are optically encoded with the position of crystalline phases along this beam. Depth-resolved material phase images are recovered via tomosynthesis. We demonstrate our technique using a heterogeneous three-dimensional object comprising three different phases; cyclotetramethylene - tetranitramine, copper and nickel, distributed in a low density medium. Our technique has wide applicability in analytical imaging and is scalable with respect to both scan size and X-ray energy.

Abstract:We demonstrate material phase identification by measuring polychromatic diffraction spots from samples at least 20 mm in diameter and up to 10 mm thick with an energy resolving point detector. Within our method an annular X-ray beam in the form of a conical shell is incident with its symmetry axis normal to an extended polycrystalline sample. The detector is configured to receive diffracted flux transmitted through the sample and is positioned on the symmetry axis of the annular beam. We present the experiment data from a range of different materials and demonstrate the acquisition of useful data with sub-second collection times of 0.5 s; equating to 0.15 mAs. Our technique should be highly relevant in fields that demand rapid analytical methods such as medicine, security screening and non-destructive testing. 12. D. Prokopiou, K. Rogers, P. Evans, S. Godber, and A. Dicken, "Discrimination of liquids by a focal construct Xray diffraction geometry," Appl. Radiat. Isot. 77, 160-165 (2013). 13. P. Evans, K. Rogers, A. Dicken, S. Godber, and D. Prokopiou, "X-ray diffraction tomography employing an annular beam," Opt. Express 22(10), 11930-11944 (2014). 14. R. D. Luggar, J. A. Horrocks, R. D. Speller, and R. J. Lacey, "Determination of the geometric blurring of an energy dispersive X-ray diffraction (EDXRD) system and its use in the simulation of experimentally derived diffraction profiles," Nucl. Instrum. Methods Phys. Res., Sect. A 383(2-3), 610-618 (1996). 15. B. Ghammraoui, V. Rebuffel, J. Tabary, C. Paulus, L. Verger, and P. Duvauchelle, "Effect of grain size on stability of X-ray diffraction patterns used for threat detection," Nucl. Instrum. Methods Phys. Res., Sect. A 683, 1-7 (2012).

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Abstract:We demonstrate a novel imaging architecture to collect range encoded diffraction patterns from overlapping samples in a single conical shell projection. The patterns were measured in the dark area encompassed by the beam via a centrally positioned aperture optically coupled to a pixelated energy-resolving detector. We show that a single exposure measurement of 0.3 mAs enables d-spacing values to be calculated. The axial positions of the samples were not required and the resultant measurements were robust in the presence of crystallographic textures. Our results demonstrate rapid volumetric materials characterization and the potential for a direct imaging method, which is of great relevance to applications in medicine, non-destructive testing and security screening. 457-460 (1987). 30. C. V. Pabón, P. Frutos, J. L. Lastres, and G. Frutos, "Application of differential scanning calorimetry and X-ray powder diffraction to the solid-state study of metoclopramide," J. Pharm. Biomed. Anal. 15(1), 131-138 (1996).

There is a compelling need for accurate, low cost diagnostics to identify osteo-tissues that are associated with a high risk of fracture within an individual. To satisfy this requirement the quantification of bone characteristics such as 'bone quality' need to exceed that provided currently by densitometry. Bone mineral chemistry and microstructure can be determined from coherent x-ray scatter signatures of bone specimens. Therefore, if these signatures can be measured, in vivo, to an appropriate accuracy it should be possible by extending terms within a fracture risk model to improve fracture risk prediction.In this preliminary study we present an examination of a new x-ray diffraction technique that employs hollow annular and semi-annular beams to measure aspects of 'bone quality'. We present diffractograms obtained with our approach from ex vivo bone specimens at Mo Kα and W Kα energies. Primary data is parameterized to provide estimates of bone characteristics and to indicate the precision with which these can be determined.