Hitachi TM1000 with Oxford EDS SEM unit
In a scanning electron microscope (SEM) electrons are used for imaging in a similar way that light microscopes use visible light. The optimal resolution of an imaging instrument depends mainly on the wavelength of the medium. Since the wavelength of electrons is much smaller than the wavelength of light, the resolution of an electron microscope is superior to that of a light microscope. In fact, it is usually more than 1,000 times better.