A light source at the top of the microscope emits a beam of electrons that travel through a vacuum in the column of the microscope. Instead of glass lenses focusing the light source in the light microscope, the TEM uses electromagnetic lenses to focus the electrons into a very thin beam. The electron beam then travels through the specimen you want to study. Depending on the density of the material present, some of the electrons are scattered and disappear from the beam. At the bottom of the microscope the rest of the electrons hit a fluorescent screen. The screen shows a shadow-like image of the specimen that can be studied directly by the operator or photographed with a camera.
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