| 摘要 |
PROBLEM TO BE SOLVED: To provide a freezing sensor optical fiber for accurately determining existence of a freezing without requiring a complicated algorithm. SOLUTION: The freezing sensor for optical fiber has a container 12 for containing water 11, an optical fiber 13 fixed to the container, a light source 14 for transmitting light to the optical fiber and a distortion measuring instrument 15. Expansion stress is transmitted to the optical fiber through the container, when the water attains the phase transition point from liquid to solid (the freezing point) due to temperature decrease. The distortion measuring instrument senses distortion generated in the optical fiber, based on the distortion dependence of Brillouin scattering light frequency and determines the presence of freezing, based on the presence of the distortion. When a pulse light source is used for the light source and the container is continuously disposed along the optical fiber, distribution of frozen state can be obtained continuously along the optical fiber. COPYRIGHT: (C)2004,JPO
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