| 摘要 |
PURPOSE:To reduce an interruption time of a line by restoring the operation quickly and automatically when a fault is recovered. CONSTITUTION:A light reflected and returned in an optical fiber 4 is branched by a photocoupler 5 and detected by a photodetector 6. A control circuit 10 stops the operation of a stimulation laser oscillator 1 in response to the detection of a light by the photo detector 6 when the stimulation laser oscillator 1 is in the normal operating state. Furthermore, the control circuit 10 operates the stimulation laser oscillator 1 over a predetermined period T2 in a predetermined period T1 when the operation of the stimulation laser oscillator 1 is stopped based on an output of a timer 12. Moreover, the control circuit 10 restarts the usual operation of the stimulation laser oscillator 1 when & reflected light stimulated by the operation of the stimulation laser oscillator 1 over the predetermined period T2 in the predetermined period T1 is not detected by the photo detector 6. |
