| 摘要 |
PURPOSE:To detect surely abnormality occurring in an optical fiber and to handle it accurately by arranging a photodetecting element where it photodetects reflected light from the optical fiber through the 1st condenser lens and a dichroic mirror. CONSTITUTION:The 1st condenser lens 16 is provided on an optical path 13 extending to the side of the optical fiber 12. Further, the photodetecting element 17 which photodetects reflected light from the optical fiber 12 is provided at the prolongation side of the optical fiber 13 at the back surface side of the dichroic mirror 11. If there is a flaw in the incidence end surface 21 of the optical fiber 12, the photodetecting element 17 decreases in the quantity of photodetection greatly as to the reflected light from the optical fiber 12. If there is a flaw at a halfway part of the optical fiber 12, reflected light from the projection side end surface is cut off, so the quantity of reflected light decreases. Consequently, a controller 17 detects abnormality of the optical fiber 12 surely and sends a control signal to a laser oscillator. |
