This is necessary since the energy distribution of secondary electrons peaks well below 10 eV.

In this case the localized image rapidly fades as energy is removed by the secondary electrons.

The range of secondary electrons depends on the energy.

One type had a funnel of sorts to capture the secondary electrons.

This affects the number of secondary electrons that escape the device surface and reach the detector.

This can for example be a light source creating secondary electrons via the photoelectric effect.

The impact of an electron to a surface can, depending on its energy and angle, release one or more secondary electrons into the vacuum.

These secondary electrons are detected by a sensor, and the image of the specimen is generated over a certain time period.

The secondary electrons will ionize far more atoms than the primary photon.

In both techniques, it is not the primary beam, but secondary electrons which cause the deposition.