The study of the use of electron lenses in the electron microscope, cathode-ray tubes, and other similar devices. The focusing of beams of positive or negative ions also relies on these methods.
Electronics and Electrical Engineering
The study of the behaviour of electron beams under the influence of magnetic and electrostatic fields in a vacuum or very low pressure gas: the analogue of light beams passing through refractive media. The applied fields form electron lenses that are used for focusing or defocusing the electron beam.