| 摘要 |
<p>PURPOSE:To accomplish measurement in a long distance by dividing the temperature measuring distance range of an optical fiber for a sensor into plural sections, dividedly controlling so that only reflected light corresponding to each measuring section may be made incident on a photodetector and adjusting the sensitivity of the photodetector corresponding to the intensity of the reflected light in each measuring section. CONSTITUTION:Light emitted from a pulse light source 2 in a measuring device 10 is conducted to the optical fiber 20 for the sensor through an optical fiber 21 and excites backscattered light, and a part of the light is conducted as the reflected light to a light branching device 32 through the optical switch 8 of the device 10 to be divided into two light beams. One of the light beams enters an OTDR measurement circuit 30a for antistokes light through an optical fiber 23a and the other light beam enters an OTDR measurement circuit 30s for stokes light through an optical fiber 23s. A switch 8 is turned on every specified time after pulse light is emitted with an opening and closing control signal from a control unit 11. Since the temperature measuring distance range of the sensor is divided into the plural sections, only reflected light corresponding to the respective sections is inputted in photodetectors 5a and 5s. By adjusting the sensitivity of the photodetector corresponding to the intensity of the reflected light of each section, the measurement in the long distance is accomplished.</p> |
