hollow-cone beam illumination

A beam illumination method by which a cone-shaped electron beam is produced. In the method, the beam is tilted to a certain angle against the optical axis by the first-stage deflection coils and is tilted back by the second-stage deflection coils to illuminate the same position on the specimen, and then the beam is rotated with respect to the optical axis kept the same illumination position. The method is used to wipe out diffraction contrast in the bright- and dark-field images and to observe the symmetries produced only by HOLZ lines without strong intensity due to ZOLZ interaction in the CBED pattern.

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