 LEED performed in a LEEM instrument (sometimes referred to as Very Low-Energy Electron Diffraction (VLEED), due to the even lower electron energies), limits the area illuminated to the beam spot, typically in the order of square micrometers.The diffraction pattern is formed in the back focal plane of the objective lens, imaged into the object plane of the projective lens (using an intermediate lens), and the final pattern appears on the phosphorescent screen, photographic plate or CCD.As the reflected electrons are bent away from the electron source by the prism, the specular reflected electrons can be measured, even starting from zero landing energy, as no shadow of the source is visible on the screen (which prevents this in regular LEED instruments).