An electron microscope is a scientific instrument which uses a beam of electrons to examine objects on a very fine scale. In an optical microscope, the wavelength of light limits the maximum magnification that is possible. As electrons have a smaller wavelength, they can achieve a higher magnification, and can see very small objects - typically around 1,000 times smaller than those seen in an optical microscope. The outline of objects, as revealed by the flow of electrons, is changed into a picture using visible light for people to see. Electron microscopes were invented in Germany in the 1930s.