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Comparison of hollow cone and axial bright field electron microscope imaging techniques
Author(s) -
Freeman L. A.,
Howi A.,
Mistry A. B.
Publication year - 1980
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1980.tb04071.x
Subject(s) - optics , contrast (vision) , contrast transfer function , cone (formal languages) , resolution (logic) , electron microscope , sign (mathematics) , materials science , physics , spherical aberration , mathematics , computer science , mathematical analysis , algorithm , artificial intelligence , lens (geology)
SUMMARY The use of hollow cone illumination in improving the contrast transfer in bright field high resolution electron micrographs is investigated experimentally. Analysis of the results on an optical bench indicates that, although the contrast transfer is free of sign reversals, the contrast is reduced by a factor of up to 3ṁ3 in relation to axial bright field imaging. This constitutes a severe limitation to the usefulness of the hollow cone bright field technique, particularly in situations where the signal to noise level is already poor, as in high resolution imaging of non‐crystalline specimens. Factors governing the contrast in hollow cone illumination are discussed.