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

The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast.