Electron beam application device

An electron beam application device comprising:

• an electron gun that includes a photocathode including a substrate and a photo electric film, a light source configured to emit pulse excitation light, and a focusing lens configured to focus the pulse excitation light toward the photocathode and that is configured to emit pulse electron beams from a position of the photo electric film where the pulse excitation light is focused;
• and
• an electron optics configured to irradiate a sample with the pulse electron beams,
• wherein the light source includes;
• a laser light source,
• a power supply configured to supply power to the laser light source to emit a pulse laser beam,
• an optical splitter configured to split a pulse laser beam emitted by the laser light source into a plurality of pulse laser beams,
• a plurality of phase adjusters each provided for a respective one of the plurality of pulse laser beams and configured to adjust phases of the pulse laser beams split by the optical splitter,
• a plurality of optical amplifiers each provided for a respective one of the plurality of pulse laser beams and configured to amplify the pulse laser beams split by the optical splitter,
• an optical combiner configured to combine the plurality of pulse laser beams whose phases are adjusted by the phase adjusters and that are amplified by the optical amplifier, and output the light from the pulse laser beams, and
• an optical phase controller configured to control phase delay amounts of the plurality of phase adjusters,
• wherein the optical phase controller stores phase delay amount data indicating the phase delay amounts of the plurality of phase adjusters in which an inclination of the pulse excitation light relative to an optical axis of the focusing lens is a predetermined value, and sets the phase delay amounts of the plurality of phase adjusters based on the phase delay amount data,
• wherein the phase delay amount data indicates phase delay amounts of the plurality of phase adjusters when the pulse excitation light is parallel to the optical axis of the focusing lens,
• wherein the light source further includes a controller configured to control the power supply and the optical phase controller,
• wherein the controller outputs a light emission control signal for controlling light emission of the laser light source to the power supply,
• wherein when the laser light source is caused to emit light having a first pulse width, the optical phase controller sets phase delay amounts of the plurality of phase adjusters based on the phase delay amount data, and
• wherein when the laser light source is caused to emit light having a second pulse width longer than the first pulse width, the optical phase controller changes a phase delay amount of at least one of the plurality of phase adjusters in a manner of increasing a focusing diameter of the pulse excitation light on the photo electric film.