Henri A Brink

US Patent:

61845248, Feb 6, 2001

Filed:

Aug 24, 1998

Appl. No.:

9/138416

Inventors:

Henri Adriaan Brink - Berkeley CA
John Andrew Hunt - Freemont CA
Michael Karl Kundmann - Downers Grove IL

Assignee:

Gatan, Inc. - Pleasanton CA

International Classification:

H01J 4700

US Classification:

250305

Abstract:

Electron optical aberrations of an energy filtering system of an energy filtering transmission electron microscope (EFTEM) are automatically corrected under computer control to set up the EFTEM for use. Optics of the electron microscope preceding an energy filter are used to scan the beam at the entrance to the filter in a pattern corresponding to a defined geometry. The beam can either be finely focused to yield a spot at each position visited during the pattern scan, or the beam can be spread out and imprinted with a well-defined intensity distribution, such as normally occurs due to passage of the beam through a specimen, so that its relative scanned displacements can be assessed using cross-correlation techniques. In the case of the finely focused beam, electron images of the scanned pattern directly yield a spot pattern image. Deviations of the recorded spot pattern image from the defined scan geometry reflect the imaging aberrations introduced by the energy filter.