An electron beam emitted from a photoexcited electron gun is increased in luminance. An electron gun 15 includes: a photocathode 1 including a substrate 11 and a photoelectric film 10; a light source 7 that emits pulsed excitation light; a condenser lens 2 that focuses the pulsed excitation light toward the photocathode; and an extractor electrode 3 that faces the photocathode and that accelerates an electron beam generated from the photoelectric film by focusing the pulsed excitation light by the condenser lens, transmitting the pulsed excitation light through the substrate of the photocathode, and causing the pulsed excitation light to be incident on the photocathode. The pulsed excitation light is condensed at different timings at different positions on the photoelectric film of the photocathode.

An electron beam apparatus includes: a cathode configured to emit electrons; an anode that is an electrode which forms an electric field such that an electron beam is formed by the electrons emitted from the cathode, and that is formed with a first hole through which the electron beam passes; an aperture member formed with an opening that shades a part of the electron beam which passes through the anode; and a convergence electrode that is an electrode which forms an electric field such that the electron beam which passes through the opening converges, and that is configured to include one single-hole electrode formed with a second hole through which the electron beam passes.

An electron beam apparatus includes: a cathode configured to emit electrons; an anode that is an electrode which forms an electric field such that an electron beam is formed by the electrons emitted from the cathode, and that is formed with a first hole through which the electron beam passes; an aperture member formed with an opening that shades a part of the electron beam which passes through the anode; and a convergence electrode that is an electrode which forms an electric field such that the electron beam which passes through the opening converges, and that is configured to include one single-hole electrode formed with a second hole through which the electron beam passes.

An electron beam emitted from a photoexcited electron gun is increased in luminance. An electron gun 15 includes: a photocathode 1 including a substrate 11 and a photoelectric film 10; a light source 7 that emits pulsed excitation light; a condenser lens 2 that focuses the pulsed excitation light toward the photocathode; and an extractor electrode 3 that faces the photocathode and that accelerates an electron beam generated from the photoelectric film by focusing the pulsed excitation light by the condenser lens, transmitting the pulsed excitation light through the substrate of the photocathode, and causing the pulsed excitation light to be incident on the photocathode. The pulsed excitation light is condensed at different timings at different positions on the photoelectric film of the photocathode.