| 摘要 |
PURPOSE:To prevent a gas laser device from making an excessive discharge current flow due to misalignment by a method wherein a signal is outputted to generate an alarm according to a difference between an output peak held by a peak holding circuit and the detection output detected by a photodetective element within a certain time. CONSTITUTION:When a gas laser tube 11 is made to start operating, a switch 15 is connected to a contact point A, and a gas laser device is controlled so as to keep its output constant. To check if the laser device is most adequate in alignment or not, the switch 15 is switched to a contact point C. The feedback signal of a photodetective element 13 is sent to a peak holding circuit 16, and the output peak of the feedback signal is held in a capacitor 17 for a long time. When the switch 15 is switched to a contact point B, the feedback signal is amplified and inputted into a comparison amplifier 19. When the gas laser tube 11 is out of alignment, the output peak becomes larger than the feedback signal, in result a signal is outputted from the comparison amplifier 19 to actuate an alarm generating circuit 21, and an alarm is generated. |
