 This can be done many different ways including, phosphorescent screens, imaging plates, CCDs, among others.After a parallel beam of low-energy electrons interacts with a specimen, the electrons form a diffraction or LEED pattern which depends on periodicity present at the surface and is a direct result of the wave nature of an electron.It is important to point out that in regular LEED the entire sample surface is being illuminated by a parallel beam of electrons, and thus the diffraction pattern will contain information about the entire surface.