The scanning electron microscope (SEM) uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. It is widely used to identify phases based on qualitative chemical analysis and/or crystalline structure. Precise measurement of very small features and objects down to nm in size is also accomplished using the SEM. Specimens can be scanned in high or low vacuum, in dry or wet conditions, and at a wide range of cryogenic or elevated temperatures. SEM is often coupled with Energy Dispersive X-Ray Spectroscopy (EDS) to further evaluate the elemental characteristic of any given specimen.