Patent ID: 7683355

Claim:
An extreme ultra violet light source apparatus which generates extreme ultra violet light by irradiating a target material with a laser beam and thereby turning said target material into plasma, said apparatus comprising: an extreme ultra violet light generation chamber in which extreme ultra violet light is generated; a target material supply unit which supplies a target material into said extreme ultra violet light generation chamber; a driver laser which generates a laser beam; a window which is provided in said extreme ultra violet light generation chamber and allows the laser beam to be transmitted into said extreme ultra violet light generation chamber, a surface of said window being disposed at an inner side of said extreme ultra violet light generation chamber; a laser beam collecting optical device which collects the laser beam generated by said driver laser to a target material supplied into said extreme ultra violet light generation chamber so as to generate plasma, said laser beam collecting optical device including an optical surface arranged in said extreme ultra violet light generation chamber; an extreme ultra violet light collecting optical device which collects the extreme ultra violet light generated from said plasma to output the extreme ultra violet light; a purge gas supply unit which supplies a purge gas for protecting at least one of (i) said surface of said window and (ii) said optical surface of said laser beam collecting optical device; a laser beam detector protection unit through which the laser beam passes after being collected by said laser beam collecting optical device; a laser beam image forming optics which forms an image of the laser beam collected by said laser beam collecting optical device; a laser beam detector which obtains information about a position at which the image of the laser beam is formed by said laser beam image forming optics; and an adjusting mechanism which carries out alignment of said laser beam collecting optical device based on the information obtained by said laser beam detector.