| 摘要 |
PURPOSE:To make it possible to exercise a supervision over an optical fiber path all the time, by detecting reflected light from a reflector unit by inputting it to a light branch unit and by sending it to a photo detecting element. CONSTITUTION:Light branch units 4 and 6 are provided to both ends of optical fiber 5, and transmistted light is inputted from LED2 to light branch unit 4 to receive a photo signal, opposite in direction to the transmitted light branched by light branch unit 4, by photo detecting element 14. On the other hand, photo detecting element 8 receives the transmitted light from light btanch unit 6 and transmitted light outputted from light branch unit 6 is selectively reflected and inputted to light branch unit 6 through reflector unit 15 before being sent to photo detecting element 14. Consequently, reflected light returning by reflecting is detected to superivise an optical fiber path all the time. |
