A stream of high voltage electrons (usually 5-100 KeV) is formed by the Electron Source (usually a heated tungsten filament) and accelerated in a vacuum toward the specimen using a positive electrical potential.
This stream is confined and focused using metal apertures and magnetic lenses into a thin, focused, monochromatic beam.
This beam is focused onto the sample using a magnetic lens
Interactions occur inside the irradiated sample, affecting the electron beam.
These interactions and effects are detected and transformed into an image.