| 摘要 |
PURPOSE:To enable the searching of a discontinuity points such as fracture point and fault point with a high resolutions, by introducing moving ultrasonic pulses along the length of an optical fiber with the time from one end of the optical fiber. CONSTITUTION:Receiving a timing signal from a timing circuit 1, a high frequency signal drive circuit 2 outputs a high frequency signal and to be transmitted along the length of an optical fiber cable 6 to be measured through a connector 5. When there is a discontinuity point such as a fault point existing in the cable 6, an ultrasonic pulse arrives at the fault point position after the propagation state thereof is changed, the backward scattered light of an optical pulse made incident turns to a return light signal to go back to the cable 6. Then, it is inputted into an avalanche photodiode 10 and converted into an electrical signal to be outputted into an amplifier 11 which sends a signal following amplification to an arithmetic circuit 12. With a high frequency signal is inputted into the circuit 12 from the circuit 2, the circuit 12 calculates the distance to the discontinuity point such as fracture point or fault point from the time difference between the high frequency signal and return light and high speed value of the ultrasonic wave propagating through the cable 6.
|
