... Microscopes In 1924 the French physicist Louis de Broglie suggested that electron beams might be regarded as a form of wave motion, similar to light. Furthermore, he reasoned that the actual wavelength of such a beam would be much shorter than that of a beam of light. The first commercial electron microscopes were built in the 1930s. The electron microscope is so named because it directs a beam of electrons rather than light through a specimen. The beam of electrons is created in a hot tungsten filament in an electron gun. This beam then travels through the length of the microscope cylinder, which houses the lenses, the specimen chamber, and the image-recording system. Two types of electron lenses are used, electrostatic and electromagnetic. They create electric and electromagnetic fields to both concentrate and move the beam. The electron microscope requires that the electron beam be in a vacuum, ...

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