| 摘要 |
PURPOSE: To prevent the emitting end face of optical fiber from damage by detecting energy of laser beam reflected with part to be machined and returned to emitting optical system and comparing it with set value. CONSTITUTION: Part of the laser beam emitted from optical fiber reaches to an energy monitor 32 through a mirror 33. The detected value of an energy monitor 32 is monitored by a comparator 35, in the case the detected value exceeds the set upper limit value and set lower limit value, an alarm signal is released so as to display in a display 36. Further, part of the laser beam reflected from machining point reaches an energy monitor 31. In case the detected value of energy monitor 31 exceeds the upper limit of comparator 33, a first abnormality detected signal is outputted and then a shutter control circuit 34 is actuated, the laser beam radiation to outside is stopped. In the case the ratio of detected values of energy monitor 31 and 32 exceeds the upper limit value, a third abnormality detected signal is outputted and then the shutter control circuit 34 is actuated. |
