ABSTRACT
All the diffraction phenomena that we have looked at so far have been the result of elastically scattered electrons, i.e. those that have not lost energy. However, as the thickness of the specimen increases, some of the electrons will lose a small amount of energy. Orienting the crystal so that the beam is along a particular zone axis has become easier now that software is available that will index diffraction patterns on-line and tilt the specimen automatically to the required axis once two other zones have been identified. Kikuchi lines will be best seen in diffraction patterns from areas of the specimen that have a low density of defects and are about half the thickness that the beam can penetrate or thicker.
