Scanning Electron Microscopy

The Parts of an EM
• Electron Microscopes (EMs) are similar in operation to optical microscopes except
that they use a focused beam of electrons instead of light to "image" the specimen and
gain information about its structure and composition.
• There are four major regions in an Electron Microscope:-
Analytical
Workshop 2012
(1) A stream of electrons is formed (by the electron source/gun) and
accelerated toward the specimen using a positive electrical potential
(2) This stream is confined and focused using metal apertures and magnetic
lenses into a thin, focused, monochromatic beam.
(3) This beam is focused onto the sample using a magnetic lens. In an SEM
the beam is then also scanned across the surface of the sample.
(4) Interactions occur inside the irradiated sample, affecting the electron
beam which are detected and transformed into an image or signal.
• The above happens in all EMs regardless of type.