Patent ID: 8817839

Claim:
A two-stage laser system comprising: an oscillation stage for producing laser light; and an amplification stage for amplifying the laser light from the oscillation stage, the amplification stage comprising: a laser chamber including a pair of electrodes for discharging electric energy to excite a laser gas in the laser chamber; and a ring resonator comprising a first optical system and a second optical system between which the laser chamber is placed, the first and second optical systems configured to create first and second optical paths running, and crossing each other, between the pair of electrodes to allow the laser light to travel in the laser chamber from the first optical system to the second optical system along the first optical path and from the second optical system to the first optical system along the second optical path, the first optical system configured to introduce the laser light from the oscillation stage to the laser chamber along the first path, partially return the laser light traveling along the second path to the laser chamber along the first path, and partially output from the two-stage laser system the laser light traveling along the second path from the second optical system, the first and second optical paths being on the same plane between the pair of electrodes, the plane being substantially orthogonal to a discharge direction of the pair of electrodes.