Scanning Electron Microscopy

Abstract

The scanning electron microscope (sem) is an instrument designed primarily for studying the surfaces of solids at high magnification. In this respect it may be compared with the optical microscope, and a set of micrographs taken on each instrument is shown in figure 2.1. The specimen is an aluminium alloy broken by ductile fracture, and it is obvious that the images are qualitatively similar but that the sem possesses much greater resolution and depth of field. If this were all, then the sem would still be a most useful microscope and indeed a very large number of its applicatioi s utilise only these advantages. But there are additional benefits which arise from using electron beams rather than light beams in image formation since the interaction of electrons with solids is more diverse than that of photons, and correct use of the sem can yield much more information—for example, on crystal orientation, chemical composition, magnetic structure or electric potential in the specimen.