Defocus and twofold astigmatism correction in HAADF-STEM
| Autor: | R.M.P. Doornbos, W. Van den Broek, R.M.M. Mattheij, ME Maria Rudnaya, Joseph M. Maubach |
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| Přispěvatelé: | Scientific Computing, Mathematics and Computer Science |
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Autofocus
business.industry Image quality Astigmatism medicine.disease Dark field microscopy Measure (mathematics) Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials law.invention Chemistry Optics law Microscopy Derivative-free optimization medicine business Focus (optics) Instrumentation Mathematics |
| Zdroj: | Ultramicroscopy, 111(8), 1043-1054. Elsevier Ultramicroscopy |
| ISSN: | 0304-3991 |
| DOI: | 10.1016/j.ultramic.2011.01.034 |
| Popis: | A new simultaneous autofocus and twofold astigmatism correction method is proposed for High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). The method makes use of a modification of image variance, which has already been used before as an image quality measure for different types of microscopy, but its use is often justified on heuristic grounds. In this paper we show numerically that the variance reaches its maximum at Scherzer defocus and zero astigmatism. In order to find this maximum a simultaneous optimization of three parameters (focus, x- and y-stigmators) is necessary. This is implemented and tested on a FEI Tecnai F20. It successfully finds the optimal defocus and astigmatism with time and accuracy, compared to a human operator. (C) 2011 Elsevier B.V. All rights reserved. |
| Databáze: | OpenAIRE |
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