Principles and applicatons of Weak Beam Image (WBI) by Cockayne et al. (Phil. Mag. 20 1256 (1969) ) and Multi Beam Image (MBI) by Hashimoto (Jernkont Ann 155 480 (1971) ) have been introduced.
Contrast mechanism of the images taken by WBI method is illustrated by a simple model and the application to the accurate determination of dislocation position and shape of G. P. zone is discussed. Contrast of high voltage (-1 Mev) electron microscopic images by WBI method and its applicability are discussed. Contrast mechanism of dislocation images in higher order Bragg reflections by Osiecki et al. (Proc EMSA Conference 178 (1971) Boston) is also discussed in terms of the extinction distance at high voltages.
Image contrast at high voltage by MBI method is discussed and the applications of this method to the determination of the nature of imperfection such as stacking faults and dislocations are discussed.
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