Animation of the inside of a transmission electron microscope (TEM), showing how it produces an image. An electron gun at the top of the column produces a beam of fast-moving electrons. These are focused by magnetic lenses , which deflect the negatively-charged electrons. A sample is introduced into the beam, absorbing and interacting with some electrons, and the remainder are focused onto a screen at the bottom. The image from this screen can be displayed on a computer. Electrons are able to image far smaller structures than visible light, as the wavelength of an electron, as described by wave-particle duality, is far smaller than that of visible light.