The most commonly used type of electron microscope in biology is called the transmission electron microscope because electrons are transmitted through the specimen to the observer. The transmission electron microscope has essentially the same design as a light microscope, but the lenses, rather than being glass, are electromagnets that bend beams of electrons. An electron gun generates a beam of electrons by healing a thin.
V-shaped piece of tungsten wire to 3000ºC. A large voltage accelerates the beam down the microscope column, which is under vacuum because the electrons would be slowed and scattered if they collided with air molecules. The magnified image can be viewed on a fluorescent screen that emits light when struck by electrons. While the electron microscope offers great improvements in resolution, electron beams are potentially highly destructive, and biological material must be subjected to a complex processing schedule before it can he examined.