| 摘要 |
PURPOSE:To improve the detecting sensitivity by constituting an optical fiber sensor, of a core part of a helical shape and a clad part for surrounding said part, and providing a sensor part extending over the overall length, which has formed the shortest distance of the outside peripheral surface of both of them to a specified thickness of below. CONSTITUTION:The periphery of a core part 12 which has been formed to a helical shape is surrounded by a clad part 11, and the shortest distance between a part of the outside peripheral surface of the core part 12 and the clad part 11 is formed to an evanescent wavelength thickness (t), and a sensor part 13 extending over the overall length of an optical fiber is constituted. When a leak oil adheres to a part of the clad part 11, light of a propagation mode is converted to a leakage mode and leaks to the outside, therefore, when its backscattering light is measured by using an optical pulse tester, a generation time and a generated position of the leakage can be detected. Also, in case the leak oil has adhered to two parts or more, the light of the propagation mode of a different angle becomes a leakage mode in the rear, and the leak oil can be detected without deteriorating the detecting sensitivity of the leak oil of the rear. |
