Patent ID: 6933500

Claim:
An electron microscope comprising: an electron beam source for emitting an electron beam; an energy filter having an energy dispersion section for dispersing the electron beam according to electron energies, and a slit for selecting the electron beam dispersed by the energy dispersion section; an energy filter control unit; an objective lens; and an energy filter electron beam detector for detecting an amount of the electron beam selected by the energy filter, wherein the energy dispersion section is adapted selectively to turn on and off, the slit is disposed in a trajectory of the electron beam dispersed by the energy dispersion section and the electron beam bypasses the slit when the energy dispersion section is turned off, and wherein the energy filter control unit is able to adjust one of the trajectory of electron beam and a position of the slit according to a signal, which is generated as a result of cyclically shifting an area on the slit illuminated by the electron beam and detected by the energy filter electron beam detector, while the energy dispersion section is turned on.