Figure 19.6.2.1

Baker, T. S.; Henderson, R.

doi:10.1107/97809553602060000703

International
Tables for
Crystallography
Volume F
Crystallography of biological macromolecules
Edited by M. G. Rossmann and E. Arnold

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International Tables for Crystallography (2006). Vol. F. ch. 19.6, p. 451 | 1 | 2 |

Figure 19.6.2.1

T. S. Baker^a ^* and R. Henderson^b

^a Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA, and ^bMedical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, England
Correspondence e-mail: tsb@bragg.bio.purdue.edu

Figure 19.6.2.1

Schematic diagram showing the principle of image formation and diffraction in the transmission electron microscope. The incident beam, $[I_{0}]$ , illuminates the specimen. Scattered and unscattered electrons are collected by the objective lens and focused back to form first an electron-diffraction pattern and then an image. For a 2D or 3D crystal, the electron-diffraction pattern would show a lattice of spots, each of whose intensity is a small fraction of that of the incident beam. In practice, an in-focus image has virtually no contrast, so images are recorded with the objective lens slightly defocused to take advantage of the out-of-focus phase-contrast mechanism.