In the electron microscope, the light source is replaced by an electron source (a tungsten filament heated in vacuum), the glass lenses are replaced by magnetic lenses and the projection screen is replaced by a fluorescent screen which emits light when struck by electrons.
There are two main types of electron microscopes (EM), the scanning EM (SEM), and the transmission EM (TEM). The main parts to an SEM are: source of electrons, a column for them to travel with electromagnetic lenses, an electron detector, sample chamber, and a computer and display to view the images.