6. Conclusions

Scanning electron microscopy is a powerful tool for observing surfaces. It now makes it possible to image the surface simultaneously from secondary electrons with great depth of field and excellent separating power at magnifications of 10 to 40,000.

SEM images can be easily combined with microanalysis and elemental mapping obtained by X-ray spectrometry. They also lend themselves easily to digitization and image processing.

A wide range of equipment is available, broadly classified into four families:

• conventional scanning electron microscopes, where the entire column is placed in a high vacuum, and maximum performance depends mainly on the type of electron source used;

• high-resolution microscopes, equipped with field emission guns and specific in-lens detectors;...