Operator using a transmission electron microscope (TEM). The operating console is seen with a TV monitor and magnified image. A beam of electrons from an electron gun is projected down the microscope column (white), passing through the sample of material to be observed, and hitting a screen which fluoresces to give the image. The electron beam is focused by electron magnets. The sample needs to be cut very thin to allow the electrons to pass through it. TEMs may demonstrate resolutions of 0.2-0.5 nanometres under perfect conditions, about 400 times better than the resolution of a scanning electron microscope.