Overzicht van elektronenmicroscopie

Light microscopes use visible light to illuminate an object, and their lenses can magnify an image up to 2000 times.  Instead of light, electron microscopes use an electron beam with a very short wavelength which allows the magnification of objects 2 to 50 million times.

An electron-emitting filament generates the electron beam, and electrostatic and electromagnetic lenses focus the beam onto a sample. The internal environment of an electron microscope is maintained under a vacuum as air molecules can deflect the electron beam.

Depending on how the electron beam interacts with the sample, electron microscopes can be divided into two types — the transmission electron microscope, or TEM, and the scanning electron microscope, or SEM .

In TEM, the electrons are transmitted through a thin sample and then used to generate a 2D image. As the electron beam passes through the sample, information about its internal composition and structure can be obtained using TEM.

In SEM, the electron beam scans a sample's surface, and then the reflected electrons are used to generate information about the 3D topography and composition of the surface.