| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of a sensor using an optical interference signal output as a sensor signal wherein a homodyne interference system is used as an optical interference signal system and has a simple constitution, the distortion of the interference output becomes large when the phase relation between a reference light to be input to the sensor and a measured light is the same phase or substantially reverse phase, a component related to the optical path length of an interferometer requires high machining accuracy and thermal expansion measures for avoiding the increase in distortion and keeping good phase relation between the reference light and measuring light. SOLUTION: In this optical fiber sensor, the phase of the reference light used as the input of the interferometer is changed by 90°and is used as a reference light of two phases. Thus, when the phase relation between the reference light of one phase and the measured light is the same phase or substantially reverse phase, the phase relation between the other reference light and the measured light is different by about 90°, and one of them always becomes an interference output of a small distortion. Therefore, by performing discrimination processing based on the front and back interference outputs to provide a sensor output, the phase variation by the machining accuracy and thermal expansion of the optical component is allowed. COPYRIGHT: (C)2011,JPO&INPIT
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