US 12,217,928 B2
Electron gun and electron microscope
Hideo Morishita, Tokyo (JP); Takashi Ohshima, Tokyo (JP); Tatsuro Ide, Tokyo (JP); Naohiro Kohmu, Tokyo (JP); Toshihide Agemura, Tokyo (JP); Yoichi Ose, Tokyo (JP); and Junichi Katane, Tokyo (JP)
Assigned to HITACHI HIGH-TECH CORPORATION, Tokyo (JP)
Appl. No. 17/798,092
Filed by Hitachi High-Tech Corporation, Tokyo (JP)
PCT Filed Mar. 25, 2020, PCT No. PCT/JP2020/013195
§ 371(c)(1), (2) Date Aug. 8, 2022,
PCT Pub. No. WO2021/192070, PCT Pub. Date Sep. 30, 2021.
Prior Publication US 2022/0406558 A1, Dec. 22, 2022
Int. Cl. H01J 37/073 (2006.01); H01J 1/34 (2006.01)
CPC H01J 37/073 (2013.01) [H01J 1/34 (2013.01); H01J 2237/053 (2013.01); H01J 2237/055 (2013.01); H01J 2237/06333 (2013.01); H01J 2237/188 (2013.01); H01J 2237/24557 (2013.01)] 14 Claims
OG exemplary drawing
 
1. An electron gun comprising:
a photocathode that has a substrate and a photoelectric film formed on the substrate;
a condenser lens configured to condense, onto the photoelectric film, excitation light emitted to the photoelectric film of the photocathode;
a first anode electrode and a second anode electrode that are arranged in an order away from the photoelectric film of the photocathode in a direction opposite to the substrate, wherein a first voltage that is positive relative to the photoelectric film of the photocathode is applied to the first anode electrode, and a second voltage that is negative relative to the first anode electrode is applied to the second anode electrode; and
an excitation optical system that includes the condenser lens and is configured to condense the excitation light on the photoelectric film, wherein:
the photocathode, the condenser lens, and the first and the second anode electrodes are disposed in a vacuum chamber in which a differential exhaust diaphragm is provided, and
the first voltage and the second voltage are controlled such that an electron beam emitted from a position of the photoelectric film on which the excitation light is condensed by the excitation optical system passes through the differential exhaust diaphragm.