Environmental Scanning Electron Microscope

The environmental scanning electron microscope or ESEM is a scanning electron microscope (SEM) that allows for the option of collecting electron micrographs of specimens that are "wet," uncoated, or both by allowing for a gaseous environment in the specimen chamber.

Although there were earlier successes at viewing wet specimens in internal chambers in modified SEMs, the ESEM with its specialized electron detectors (rather than the standard Everhart-Thornley detector) and its differential pumping systems to allow for the transfer of the electron beam from the high vacuums in the gun area to the high pressures attainable in its specimen chamber make it a complete and unique instrument designed for the purpose of imaging specimens in their natural state. The instrument was designed originally by Gerasimos Danilatos while working at the University of New South Wales.