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On-Line Aberration Measurement and Correction in STEM

Published online by Cambridge University Press:  02 July 2020

Ondrej L. Krivanek
Affiliation:
MP group,Cavendish Laboratory, University of Cambridge, CambridgeCB3 OHE, UK
Niklas Dellby
Affiliation:
MP group,Cavendish Laboratory, University of Cambridge, CambridgeCB3 OHE, UK
Andrew J. Spence
Affiliation:
MP group,Cavendish Laboratory, University of Cambridge, CambridgeCB3 OHE, UK
Roger A. Camps
Affiliation:
MP group,Cavendish Laboratory, University of Cambridge, CambridgeCB3 OHE, UK
L. Michael Brown
Affiliation:
MP group,Cavendish Laboratory, University of Cambridge, CambridgeCB3 OHE, UK
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Extract

Aberration correction in electron microscopy is a subject with a 60 year history dating back to the fundamental work of Scherzer. There have been several partial successes, such as Deltrap's spherical aberration (Cs) corrector which nulled Cs over 30 years ago. However, the practical goal of attaining better resolution than the best uncorrected microscope operating at the same voltage remains to be fulfilled. Combining well-known electron-optical principles with stable electronics, versatile computer control, and software able to diagnose and correct aberrations on-line is at last bringing this goal within reach.

We are building a quadrupole-octupole Cs corrector with automated aberration diagnosis for a VG HB5 dedicated scanning transmission electron microscope (STEM). A STEM with no spherical aberration will produce a smaller probe size with a given beam current than an uncorrected STEM, and a larger beam current in a given size probe.

Type
The Limits of Image Resolution: Seeing is Believing
Copyright
Copyright © Microscopy Society of America 1997

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References

1.Scherzer, O., Zeitchrift Physik 101 (1936) 593 and Optik 2, (1947) 114.10.1007/BF01349606CrossRefGoogle Scholar
2.Deltrap, J.H.M., Ph.D. thesis, U. of Cambridge (1964).Google Scholar
3.Krivanek, O.L., Spence, A.J. and Dellby, N., to be published.Google Scholar
4.Krivanek, O.L. and Stadelmann, P.A., Ultramicroscopy 60 (1995) 103.10.1016/0304-3991(95)00050-BCrossRefGoogle Scholar