Browsing by Author "Elarnaut, F."
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Item Open Access Confocal energy-dispersive X-ray diffraction tomography employing a conical shell beam(Optical Society of America, 2019-07-01) Dicken, Anthony; Evans, J. Paul O.; Rogers, Keith; Prokopiou, Danae; Godber, Simon; Elarnaut, F.; Shevchuk, Alex; Downes, D.; Wilson, M.We introduce a new high-energy X-ray diffraction tomography technique for volumetric materials characterization. In this method, a conical shell beam is raster scanned through the samples. A central aperture optically couples the diffracted flux from the samples onto a pixelated energy-resolving detector. Snapshot measurements taken during the scan enable the construction of depth-resolved dark-field section images. The calculation of dspacing values enables the mapping of material phase in a volumetric image. We demonstrate our technique using five ~15 mm thick, axially separated samples placed within a polymer tray of the type used routinely in airport security stations. Our method has broad analytical utility due to scalability in both scan size and X-ray energy. Additional application areas include medical diagnostics, materials science, and process controlItem Open Access Sparse interleaved sampling for high resolution focal construct geometry X-ray tomography(Optical Society of America, 2023-04-24) Evans, J. Paul O.; Elarnaut, F.; Downes, D.; Lee, W. K.; Arnold, Emily; Rogers, KeithWe demonstrate interleaved sampling by multiplexing conical subshells within the tomosynthesis and raster scanning a phantom through a 150 kV shell X-ray beam. Each view comprises pixels sampled on a regular 1 mm grid, which is then upscaled by padding with null pixels before tomosynthesis. We show that upscaled views comprising 1% sample pixels and 99% null pixels increase the contrast transfer function (CTF) computed from constructed optical sections from approximately 0.6 line pairs/mm to 3 line pairs/mm. The driver of our method is to complement work concerning the application of conical shell beams to the measurement of diffracted photons for materials identification. Our approach is relevant to time-critical, and dose-sensitive analytical scanning applications in security screening, process control and medical imaging.