| 摘要 |
PURPOSE:To securely protect a human body from laser light even when an optical fiber is not connected and disconnected by guiding reflected light obtained from one output of an optical directional coupler from the other output point to a photoelectric converting circuit and turning off the light emission of an optical signal. CONSTITUTION:The output terminal of an optical signal output circuit 1 which uses a laser diode as a light emitting element is connected to the optical directional coupler 2 and the optical signal from the optical signal output circuit 1 is propagated from a 1st output point 3 of the optical directional coupler 2 to an optical connector 4. If the optical signal is reflected in the optical connector 4 owing to a nonconnection point or disconnection point, the reflected light is inputted from the 1st output point 3 to the optical directional coupler 2 again and inputted from a 2nd output point 7 to the photoelectric converting circuit 6 to become an electric signal. This electric signal is inputted to the control terminal 5 of the optical signal output circuit 1 to turn off the output of the optical signal output circuit 1. Thus, when the optical connector 4 is not connected or when the optical path is disconnected, the laser light turns off instantaneously to securely protect the human body. |
