Patent ID: 8811436

Claim:
A laser apparatus, comprising: a master oscillator configured to output a laser beam; at least one amplifier disposed in a beam path of the laser beam from the master oscillator; at least one power source for applying a high-frequency voltage to the at least one amplifier; and a controller for varying the high-frequency voltage to be applied to the at least one amplifier from the at least one power source, wherein the controller is configured to: control the high-frequency voltage applied to the at least one amplifier from the at least one power source so that the at least one amplifier is retained at a first excitation intensity during a first period, and control the high-frequency voltage applied to the at least one amplifier from the at least one power source so that the at least one amplifier is retained at a second excitation intensity during a second period, and the first excitation intensity is above the second excitation intensity.