A very widely used technique to study surface topography. A high energy (typically 10keV) electron beam is scanned across the surface. The incident electrons cause low energy secondary electrons to be generated, and some escape from the surface. The secondary electrons emitted from the sample are detected by attracting them onto a phosphor screen. This screen will glow and the intensity of the light is measured with a photomultiplier.

The incident electrons will also cause X-rays to be generated which is the basis of the EDX technique. Some of the incident electrons may strike an atomic nucleus and bounce back into the vacuum. These electrons are known as backscattered primaries and can be detected with a backscattered electron detector. Backscattered electrons can also give information on the surface topography and on the average atomic number of the area under the electron beam.