Scanning electron microscopy at low vacuum in specimen chamber

Observation of specimens at a low vacuum in the specimen chamber brings some advantages in comparison with observation in a high vacuum. Water-containing and electrically non-conductive specimens are of special significance. The principle of low vacuum microscopes and problems with the interaction of electrons with the gaseous medium are described. Detection of signals in the so-called environmental (low vacuum) microscope is realised with the help of a single crystal YAG scintillation detector of backscattered electrons on which an electrode system for ionisation detection of secondary electrons is deposited. Some examples of insulation specimens, wet specimens and biological specimens of soft tissues are presented