20 research outputs found
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High-resolution CT system for elemental mapping
The performance of a low-temperature CCD camera for application in computed tomography (CT) was tested on beamline II-3 at the Stanford Synchrotron Radiation Laboratory (SSRL). In the present system, transmitted x-rays are converted to visible light on a phosphor-coated optical face plate. This light illuminates a thermoelectrically cooled CCD, which is operated as a charge counting device. By modulating the energy of the x-ray beam, we can obtain elemental and chemical-state information about the reconstructed voxels. Presently, the resolution is about 50 microns, and is to a large extent controlled by the quality of the phosphor. The spatial resolution and chemical sensitivity of the system are reported. Applications to materials and biological sciences are discussed
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Micro-tomography using synchrotron radiation
This paper discusses the results of recent experiments at Stanford Synchrotron Radiation Laboratory (SSRL) and Hamburger Synchrotronstrahlungslabor (HASYLAB) which were designed to explore the feasibility of using synchrotron radiation in high-resolution, computerized, critical-absorption tomography. The results demonstrate that it is possible, using absorption-edge differencing, to identify adjacent elements in the periodic table with high sensitivity. Furthermore, by using the fine structure in the absorption spectra, it is possible to distinguish between regions of different chemical states. Methods of using synchrotron radiation for high-resolution, three-dimensional chemical-state mapping in small samples are discussed