Electron optics is a mathematical framework for the calculation of electron trajectories in the presence of electromagnetic fields. The term optics is used because magnetic and electrostatic lenses act upon a charged particle beam similarly to optical lenses upon a light beam.

An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing them to produce magnified images or electron diffraction patterns. As the wavelength of an electron can be up to 100,000 times smaller than that of visible light, electron microscopes have a much higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes. Electron microscope may refer to:Transmission electron microscopy (TEM) where swift electrons go through a thin sample Scanning transmission electron microscopy (STEM) which is similar to TEM with a scanned electron probe Scanning electron microscope (SEM) which is similar to STEM, but with thick samples Electron microprobe similar to a SEM, but more for chemical analysis Ultrafast scanning electron microscopy, version of a SEM that can operate very fast Low-energy electron microscopy (LEEM), used to image surfaces Photoemission electron microscopy (PEEM) which is similar to LEEM using electrons emitted from surfaces by photons