Development of an ellipse fitting method with which to analyse selected area electron diffraction patterns.
A software method has been developed which uses ellipse fitting to analyse electron diffraction patterns from polycrystalline materials. The method, which requires minimal user input, can determine the pattern centre and the diameter of diffraction rings with sub-pixel precision. This enables accurate crystallographic information to be obtained in a rapid and consistent manner. Since the method fits ellipses, it can detect, quantify and correct any elliptical distortion introduced by the imaging system. Distortion information derived from polycrystalline patterns as a function of camera length can be subsequently recalled and applied to single crystal patterns, resulting in improved precision and accuracy. The method has been implemented as a plugin for the DigitalMicrograph software by Gatan, and is a freely available via the internet.
Electron Microscopy Centre, Australian Institute for Innovative Materials, Innovation Campus, University of Wollongong, North Wollongong, NSW 2500, Australia. Electronic address: dmitchel@uow.edu.au.
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Mitchell
Electron Microscopy Centre, Australian Institute for Innovative Materials, Innovation Campus, University of Wollongong, North Wollongong, NSW 2500, Australia; Catalyst Fundamentals, Fischer-Tropsch and Syngas Conversion Research, Sasol Technology R & D, Sasolburg 1947, South Africa.
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Van den Berg
Distortion; Electron diffraction; Ellipse fitting; software analysis