ELECTRON MICROSCOPE

摘要

Disclosed is an electron microscope, wherein a magnetic field immersion-type cold-FE electron gun (1) comprises: a cold cathode field emission electron source (101); a magnetic lens (120) positioned at the circumference of the electron source; and getter pumps (16a, 16b) for improving the degree of vacuum inside the electron gun. When the electron source is cleaned (409), the parameters of the electron optical system after cleaning are returned to the same values as the parameters before cleaning (410, 404). As a result, the electron gun and electron microscope can be provided with high observation efficiency and the focal distance of the electron gun does not change during use.