Patent ID: 7382816

Claim:
A two-stage laser pulse energy control device, comprising: a two-stage laser which is comprised of an optical oscillation stage in which energy charged in an oscillating capacitor is subjected to pulse compression and applied to a pair of mutually opposed electrodes disposed in an oscillating chamber to excite laser gas in the oscillating chamber so as to output seed light, and an optical amplification stage in which energy charged in an amplifying capacitor is subjected to pulse compression and applied to a pair of mutually opposed electrodes disposed in an amplifying chamber to excite laser gas in the amplifying chamber so as to amplify the seed light injected into the amplifying chamber to output a laser beam; a first monitor module which measures a pulse energy Posc of the seed light; and a second monitor module which measures a pulse energy Pamp of the laser beam, and controlling the pulse energy Pamp of the laser beam, wherein: the optical oscillation stage is controlled according to a measured result of the first monitor module so that the pulse energy Posc of the seed light becomes a prescribed energy Es 0 or more, the optical amplification stage is controlled according to a measured result of the second monitor module so that the pulse energy Pamp of the laser beam becomes a target energy Patgt of the optical amplification stage, and the prescribed energy Es 0 is set to a lower limit energy value of amplification saturation region which is a threshold value between an amplification saturation region in which the pulse energy Pamp of the laser beam saturates without increasing substantially even if the pulse energy Posc of the seed light increases, and a region other than the amplification saturation region in which the pulse energy Pamp of the laser beam increases as the pulse energy Posc of the seed light increases.