The Advanced Photon Source Upgrade (APS-U) project is set to revolutionize hard x-ray research. The upgraded machine will provide increase coherent flux and brightness in x-ray beams by a factor of 500. Many x-ray techniques will significantly benefit from this enhancement, particularly in terms of speed and achievable resolution. The Imaging Group at APS operates three specialized beamlines—2-BM, 7-BM, and 32-ID—focused on full-field imaging and ultra-high-speed applications. These beamlines cover up to three orders of magnitude in both spatial and temporal resolution. As part of the APS-U, the Imaging Group will further improve its capabilities, especially in terms of speed and image quality. These advancements will enable new possibilities for researchers conducting multi-scale, multi-modal, and time-resolved experiments. A significant addition to the group will be the future installation of a Projection Microscope at 32-ID, which will bridge the resolution gap between nano-tomography, currently achieved with the Transmission X-ray Microscope at 32-ID, and micro-tomography at 2-BM and 7-BM.
Purpose: Tomography using diffracted x-rays produces reconstructions mapping quantities such as crystal lattice parameter(s), crystallite size, and crystallographic texture, information quite different from that obtained with absorption or phase contrast. Diffraction tomography is used to map an entire blue shark centrum with its double cone structure (corpora calcerea) and intermedialia (four wedges).
Approach: Energy dispersive diffraction (EDD) and polychromatic synchrotron x-radiation at 6-BM-B, the Advanced Photon Source, were used. Different, properly oriented Bragg planes diffract different x-ray energies; these intensities are measured by one of ten energy-sensitive detectors. A pencil beam defines the irradiated volume, and a collimator before each energy-sensitive detector selects which portion of the irradiated column is sampled at any one time. Translating the specimen along X , Y, and Z axes produces a 3D map.
Results: We report 3D maps of the integrated intensity of several bioapatite reflections from the mineralized cartilage centrum of a blue shark. The c axis reflection’s integrated intensities and those of a reflection with no c axis component reveal that the cone wall’s bioapatite is oriented with its c axes lateral, i.e., perpendicular to the backbone’s axis, and that the wedges’ bioapatite is oriented with its c axes axial. Absorption microcomputed tomography (laboratory and synchrotron) and x-ray excited x-ray fluorescence maps provide higher resolution views.
Conclusion: The bioapatite in the cone walls and wedges is oriented to resist lateral and axial deflections, respectively. Mineralized tissue samples can be mapped in 3D with EDD tomography and subsequently studied by destructive methods.
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