US Patent No. 10,194,515

BEAM DELIVERY SYSTEM AND CONTROL METHOD THEREFOR


Patent No. 10,194,515
Issue Date January 29, 2019
Title Beam Delivery System And Control Method Therefor
Inventorship Yoshifumi Ueno, Oyama (JP)
Takashi Suganuma, Oyama (JP)
Yoshiaki Kurosawa, Oyama (JP)
Assignee Gigaphoton Inc., Tochigi (JP)

Claim of US Patent No. 10,194,515

1. A beam delivery system configured to deliver a pulse laser beam outputted from a laser apparatus to a target in an extreme ultraviolet light generation apparatus configured to generate extreme ultraviolet light by irradiating the target with the pulse laser beam, the beam delivery system comprising:a plurality of beam adjusters configured to adjust a divergence angle of a pulse laser beam outputted from the laser apparatus;
a beam sampler configured to separate a part of the pulse laser beam outputted from a first beam adjuster provided at the most downstream among the plurality of beam adjusters to acquire a sample beam;
a beam monitor configured to receive the sample beam and output a monitored diameter; and
a beam delivery controller configured to control the plurality of beam adjusters based on the monitored diameter,
wherein the beam delivery controller is configured to:
adjust each of beam adjusters other than the first beam adjuster selected one after another from the most upstream so that the monitored diameter at the beam monitor becomes a predetermined value specific to the beam adjuster; and
adjust the first beam adjuster so that the pulse laser beam becomes focused at a position downstream of a target position, and
wherein the first beam adjuster is a final-stage beam adjuster in the beam delivery system.