Microsc. Microanal. Microstruct. 3, 187-199 (1992)
DOI: 10.1051/mmm:0199200302-3018700

Design and first applications of a post-column imaging filter

Ondrej L. Krivanek, Alexander J. Gubbens, Niklas Dellby et Christopher E. Meyer

Gatan Research and Development, 6678 Owens Drive, Pleasanton, CA 94588, U.S.A.

Abstract
We have designed and built an imaging filter which can be attached to most standard TEMs, and is capable of operating at primary energies of up to 400 keV. The filter uses a 90° magnetic sector prism, a piezoelectrically controlled energy-selecting slit, and 6 quadrupole and 5 sextupole lenses. It fully corrects second-order aberrations and distortions in images formed with electrons of selected energies, and it also produces second-order aberration-corrected spectra of variable dispersion. We show the first applications of the filter at 200 keV primary energy, which indicate that the filter will excel in chemical mapping and spectroscopy, in improving contrast of electron images and diffraction patterns, and in making high resolution electron microscopy and diffraction more quantitative. We conclude the paper with a discussion about atomic resolution image formation using inelastically scattered electrons, and the relationship between energy-filtered diffraction patterns and images formed with electrons of the same energy.

PACS
0778 - Electron, positron, and ion microscopes; electron diffractometers.
8280 - Chemical analysis and related physical methods of analysis.

Key words
TEM -- Energy filtering -- Image resolution -- Electron optics -- Chemical composition -- Atomic structure -- Thorium oxides


© EDP Sciences 1992