| 摘要 |
PURPOSE:To enhance response and to facilitate the setting of a threshold value, by setting state change quantity measured by an abnormality detection means to the strain quantity of a fiber. CONSTITUTION:The power laser beam from a laser oscillator 1 is condensed by a condensing lens 2 to be transmitted through a power laser transmitting fiber 3 from one end thereof and allowed to irradiate from the other end thereof. At this time, the strains of the respective parts of the fiber 3 detected by a plurality of the strain detection elements 4a-4e provided to the respective parts such as the laser input end part, intermediate parts and laser output end part of the fiber 3 are measured by a strain measuring device 5 and the signal of said device 5 is operated in its magnitude by a signal processor 6 to be transmitted to a laser output controller 7. The laser output controller 7 controls the output of the laser oscillator 1 so as to stop the oscillation of power laser beam when the transmitted operation output of said processor 6 exceeds a preset threshold value.
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