Patent ID: 7720118

Claim:
A laser unit comprising: a laser oscillator; a laser power supply for supplying power to the laser oscillator; a laser output detector for measuring a laser output of the laser oscillator; a laser beam absorber for absorbing laser beam; and a controller for controlling the laser oscillator, the laser power supply, the laser output detector and the laser beam absorber upon receiving a laser output command, wherein the controller includes: a trial conducting part for conducting, in a preparation process of the laser oscillator after the laser oscillator is activated and before the laser oscillator is ready to be stably used, a trial of laser oscillation in which the laser output detector measures the laser output after the laser oscillator oscillates a laser beam for a predetermined time, while the laser beam absorber absorbs at least a part of the oscillated laser beam; a judging part for judging, in the trial of laser oscillation by the trial conducting part, whether the laser output measured by the laser output detector satisfies a criterion predetermined based on a stable output condition of the laser unit; and an iteratively activating part for automatically alternating two states in which the trial conducting part conducts the trial of laser oscillation and the laser oscillator is suspended, until the judging part judges that the predetermined criterion is satisfied, wherein the predetermined criterion is that the difference, between two laser outputs measured in continuous two trials of laser oscillation, is equal to or smaller than a predetermined value.