| 摘要 |
PURPOSE:To prevent the overheat, etc. of a laser tube due to large current arc discharge, and to avoid the damage, etc. of a laser device by instantaneously turning a laser power supply OFF when the flow of a refrigerant is stopped or reduced and normal cooling is not conducted. CONSTITUTION:An output from a revolution indicator 7 outputting an electric signal proportional to the number of revolution of a prime mover for a pressure pump 6 is compared with a reference signal by a comparison circuit 8, and a reaching to some number of revolution or less of the number of revolution of the prime mover is detected. When there is a substance preventing the flow of a refrigerant between a tank 5 and a pressure gage 9 even when the pressure pump 6 is stopped or the pressure pump 6 is operated normally, an output signal from the pressure gage 9 is magnified, and the output signal is detected by a comparison circuit 10. When there is a substance disturbing a flow between the tank 5 and the pressure gage 9, the output signal from the pressure gage 9 is made small, and the output signal is detected by a comparison circuit 11. A power supply 3 is turned OFF respectively. Accordingly, the overheat of an oscillator 1, particularly, a laser tube 2, and the power supply 3 can be prevented. |
