ATOMIC-NUMBER AND CRYSTALLOGRAPHIC CONTRAST IMAGES WITH THE SEM - A REVIEW OF BACKSCATTERED ELECTRON TECHNIQUES

Using SEM backscattered electron techniques, three types of image can be obtained: atomic number contrast (Z-contrast), images based on changes in crystal structure, and electron channelling patterns, distinct configurations of lines and bands of different contrasts which are unique for a particular crystal structure (orientation). Electron channelling patterns (ECP) need subsequent interpretation, which depends on the crystal structure and the relationship between crystal and specimen coordinate systems. A general solution is presented, involving the construction of reference ECP maps over the surface of a sphere.-R.A.H.