Practical experience with computer-controlled high-resolution electron microscopy

The recent proliferation of the so-called intermediate-voltage HREMs has led to a vast expansion in the ranges of materials which are nowadays being examined on the atomic scale. Impressive-looking micrographs containing detail as fine as 1A are comparatively easy to obtain. However, relating this image information in a quantitative manner to particular features of the object can be tedious and time-consuming even when the imaging conditions (eg. objective lens focus, illumination angle, focal spread) and the specimen parameters (eg. thickness, orientation, composition) are well-known. The presence of residual astigmatism and/or incident beam misalignment leads to spurious image features which can seriously compromise this process of interpretation, but it is difficult, even for skilled operators, to adjust these variables with sufficient precision that their effects are negligible.