Abstract
The various electron microscopical methods for measuring small rigid-body displacements at edge-on boundaries are examined. In particular, the ways in which local lattice-fringe shifts and Fresnel-like fringe intensities depend on the displacement are considered in detail. It is concluded that the most accurate method currently available for the measurement of such displacements involves the direct measurement of lattice-fringe displacements. Analysis of an experimental image, of a Σ = 3(111) twin boundary in copper, showed that this measurement can be carried out to an accuracy of about 2% of the lattice-fringe spacing, provided adequate precautions are taken.