Abstract: There is disclosed a low-vacuum scanning electron microscope wherein a bias voltage is applied to a specimen. A primary electron beam is made to strike the specimen, producing secondary electrons which are accelerated by an electric field producing an electron avalanche effect. Positive ions traveling toward the specimen reach the specimen or specimen holder. Then, the electrons lose their electric charge and return to molecules. In this way, a scanned image corresponding to a secondary electron image can be obtained based on the specimen current.

Abstract: A scanning electron microscope permitting observation of raw biological specimens containing moisture. A vessel accommodating water supplied to the specimen is formed. A passage is formed in the specimen chamber of the microscope to convey the liquid from the vessel to the specimen. A pipe for introducing a gas such as air is connected with the passage. The introduced gas leaks around the specimen after flowing through the passage to prevent the liquid from freezing in the vessel and in the passage when the specimen chamber is evacuated to a vacuum.