Imaging of hard X -rays with a multilayer Kirkpatrick -Baez CCD microscope in the laboratory and at the synchrotron
Abstract
An improved Kirkpatrick-Baez hard x-ray microscope with spherical multilayer mirrors and a fully electronic CCD camera detector has been designed, built, tested and successfully used in the laboratory and at the synchrotron. This microscope is an improved tool for submicron imaging of materials structure, composition and dynamics, which will allow higher resolution and faster investigations of semiconductor microstructures, magnetic domains and other advanced materials problems. We have demonstrated x-ray image acquisition at the video rate of 60 frames per second using a synchrotron source, a large advance over previous capabilities. The microscope field of view can be 140 μm by 140 μm, with a measured resolution less than 1 μm, a limit imposed to date by the detector pixel size. Computer simulations predict an intrinsic resolution down to 0.2 μm, making this device equivalent in resolution to slower x-ray microprobes, with significantly faster imaging speed. The improved microscope performance is a result of extensive computational and laboratory studies of the effects of x-ray mirror slope error, roughness, and other ray fluorescence emitted by an object illuminated by a synchrotron x-ray beam. Such applications will likely require the higher intensities predicted for the next generation imperfections on image quality. The microscope has been used for hard x-ray imaging in both absorption and diffraction modes. The former is useful for imaging of buried x-ray absorbing structures in matrices partially transparent to x-rays. The latter is suited for imaging of opaque, but reflective structures such as microelectronic devices of silicon and gallium arsenide crystalline wafers. The microscope resolution is four times higher at the synchrotron than in the laboratory, when imaging absorption. The resolution of diffraction imaging in the laboratory is equivalent to the resolution of absorption imaging at the synchrotron, however the synchrotron imaging is always vastly faster. We have also investigated the possibility of using this microscope design for x-ray fluorescence microscopy, where the image is formed from the characteristic x-ray fluorescence emitted by an object illuminated by a synchrotron x-ray beam. Such applications will likely require the higher intensities predicted for the next generation synchrotron sources.
Degree
Ph.D.
Advisors
Durbin, Purdue University.
Subject Area
Chemistry
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