Ultraviolet laser device

An ultraviolet laser device, comprising:

• a laser beam output unit that includes a first fiber amplifier, a second fiber amplifier, and a third fiber amplifier that respectively output a first infrared laser beam, a second infrared laser beam, and a third infrared laser beam at infrared wavelengths;
• and
• a wavelength conversion unit that includes a first optical system into which the first infrared laser beam is incident and through which the first infrared laser beam is propagated and outputted as a first laser beam, a second optical system into which the second infrared laser beam is incident and through which it is propagated and outputted as a second laser beam, a third optical system into which the third infrared laser beam is incident and through which it is propagated and outputted as a third laser beam, and a fourth optical system into which the first laser beam, the second laser beam, and the third laser beam that have respectively been outputted from the first optical system, the second optical system, and the third optical system are incident after having been combined, and through which they are propagated, wherein:
• the first fiber amplifier is an ytterbium doped fiber amplifier;
• the second fiber amplifier is a thulium doped fiber amplifier;
• the third fiber amplifier is an ytterbium doped fiber amplifier or an erbium doped fiber amplifier;
• the first optical system wavelength converts the first infrared laser beam to a predetermined harmonic wave, and generates the predetermined harmonic wave as the first laser beam;
• the fourth optical system includes a first wavelength conversion element and a second wavelength conversion element;
• the first wavelength conversion element generates an earlier stage ultraviolet laser beam in the ultraviolet region by sum frequency generation between the predetermined harmonic wave and the second laser beam;
• and
• the second wavelength conversion element generates an ultraviolet laser beam by sum frequency generation between the earlier stage ultraviolet laser beam and the third laser beam.