The problem of characterizing twin boundaries in crystals which had an element of pseudo-symmetry was examined by using diffraction contrast techniques. It was pointed out that the situation was quite different to that in conventional diffraction contrast techniques because a number of closely spaced nearly-common reflections passed through the objective aperture. It was also different to conventional phase-contrast imaging because these reflections were not dynamically coupled. The results which were obtained showed that high precision could be achieved in measurements of the rigid body translation vector.

D.J.Seale, S.S.Sheinin: Materials Science Forum, 1996, 207-209, 341-4