ABSTRACT
The scanning electron microscope (SEM) is similar to the transmission electron microscope (TEM) in that they both employ a beam of electrons directed at the specimen. This means that certain features, such as the electron gun, condenser lenses and vacuum system, are similar in both instruments. However, the ways in which the images are produced and magnified are entirely different, and whereas the TEM provides information about the internal structure of thin specimens, the SEM is primarily used to study the surface, or near surface, structure of bulk specimens. Figure 5.1 is a scanning micrograph showing the surface of a metal alloy. It is much easier for the eye to interpret this type of image than a transmission electron image.
