| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber sensor capable of measuring quasi-static physical quantitys such as temperature and depth. SOLUTION: This optical fiber sensor has a light source part 2 for sending out a frequency-modulated laser beam and a sensing optical fiber 32 for changing the length being an optical path according to a physical quantity of a measuring object, and has a sensor part 3 for making the reflected laser beam interfere with a reference laser beam by passing the laser beam sent out of the light source part 2 through the sensing optical fiber, an O/E converting part 4 for converting the interfered laser beam into an electric signal, a higher harmonic wave component extracting part 6 for extracting a higher harmonic wave component included in the interfered laser beam on the basis of the electric signal, and a demodulating part 7 for calculating an optical path differenceΔL and static pressure P on the basis of a modulation index C when judged as being in an allowable error range on the basis of a phase differenceϕof the interfered light by calculating the phase difference and the modulation index C of the interfered light on the basis of the amplitude ratio of the extracted higher harmonic wave component.
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