It was recalled that dislocations with a large edge component did not exhibit a full loss of diffraction contrast in the transmission electron microscope unless the conditions, g•b = 0 and g•b x u = 0 were satisfied simultaneously. Because of a similarity between transmission electron microscopy diffraction contrast and electron channelling contrast in the scanning electron microscope, the same contrast rules were expected to apply to electron channelling contrast imaging. By studying the characteristic edge dislocations which formed in annealed FeAl samples, it was demonstrated that the same extinction conditions indeed applied to transmission electron microscopic diffraction contrast and to electron channelling contrast imaging.

Demonstration of the g•b x u = 0 Edge Dislocation Invisibility Criterion for Electron Channelling Contrast Imaging. M.A.Crimp, B.A.Simkin, B.C.Ng: Philosophical Magazine Letters, 2001, 81[12], 833-7