| 摘要 |
PROBLEM TO BE SOLVED: To provide an interference type optical fiber sensor which can elimi nate polarization rotation noises due to the difference of birefringence of optical fibers, and which has a high signal-noise ratio. SOLUTION: A pulse light E<SB>0</SB>emitted from a pulse light source 1a is divided into two pulse lights EA and EB at a reference part 3. The pulse light EA is delayed by a reference fiber 32, multiplied with the pulse light EB propagated in a direct fiber 33, and then sent to a sensing part 5. The sensing part 5 sends a coherent light EAB+EBA which detects loads and pulse lights EAA and EBB which have the same polarization condition as the coherent light EAB+EBA to a processing part 6. In the processing part 6, a demodulator 64a demodules a phase of the coherent light EAB+EBA, a polarization condition calculator 65 of the processing part 6 calculates the polarization condition using the pulse lights EAA and EBB having the same polarization condition as the coherent light EAB+EBA, and a polarization rotation noise eliminator 66 divides polarization rotation noises calculated by the polarization condition calculator 65 using the output from the demodulator 64a and then outputs the result. COPYRIGHT: (C)2004,JPO
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