bend contour (equal inclination fringe)

When a crystalline specimen is bent, the dark-field image of the specimen shows strong intensities at positions where a Bragg condition is satisfied, thus the positions being seen to be bright. The bright-field image of the positions is complementarily dark. Since the crystallographic orientation of the positions is equal with respect to the incident beam, they give an equal intensity. The intensity contours are termed equal inclination fringes or bend contours. The bend contours reveal the bend feature of a crystalline specimen. It should be noted that if only one reflection is strongly excited, not only the principal maximum line but also subsidiary maxima lines appear due to a strong dynamical effect.

TEM images of bend contours in a mica taken at an accelerating voltage of 200 kV.
(a)Bright-field image.
(b), (c), (d), (e) and (f) Dark-field images formed by reflections indicated in diffraction pattern (g).
(g)Diffraction pattern acquired from the same field.

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