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Electron microscope

Transmitting electron microscope Optical microscopes can only magnify objects up to 2000 times—greater magnifications do not reveal any more detail. Electron microscopes can magnify objects millions of times. The first electron microscope, which could magnify objects up to 400 times, was built in 1932 by German engineers Ernst Ruska and Max Knoll. In their instrument, the image was made not by light but by a beam of tiny subatomic particles called electrons. The images created by electron microscopes are called electron micrographs. They may be viewed on television screens using video cameras, or digitized and viewed on computer screens.


How it works

A diagram of a scanning electron microscopeIn an electron microscope, a beam of tiny particles called electrons does the same job as light in an optical microscope. It is fired at the object and then focused by electromagnetic “lenses” on to a screen that emits light where the electrons hit it.
A coloured scanning electron micrograph of a snowflake

Types of electron microscope

There are more than 40 different types of microscope, apart from optical microscopes, in use today.

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