| 摘要 |
PROBLEM TO BE SOLVED: To measure even a long-sized fiber having a branching loss, at high distance resolution and high sensitivity with a simple constitution. SOLUTION: Frequency sweep light Pb which is coherent light and whose optical frequency varies with time is branched into probe light Pc and reference light Pd, and probe light Pc is made to come into an optical fiber 1 to be measured, and its return light Pe is received. The reference light Pd is pulsated by a pulse modulator 31, and its reference light pulse Pf goes around inside a loop-like optical path of an optical loop delay apparatus 33. The reference light pulse Pf(j) delaying by desired circumferences passes through an optical gate 36 and is multiplexed with the return light Pe. The multiplexed light Pg is made to come into a receiver 41, and beat components E of both lights are obtained. The number of circumferences of the reference light pulse Pf(j) is set by a control section 50, and the reflective position of the optical fiber 1 to be measured can be specified based on the frequencies of the beat components E and the number of circumferences of reference light pulses Pf(j) thereof. COPYRIGHT: (C)2010,JPO&INPIT
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