| 摘要 |
A phase difference calculation method, a device (34), and a system (38) are disclosed. In an optical fiber ring interference sensor (37) using a 3x3 optical splitting coupler (30) and an optical splitting coupler (12), linear sections are determined in advance, where a relationship between a phase difference theta of propagation lights and an intensity Ppdn (n=1, 2, 3) outputted from each photo detector (15-1, 15-2, 15-3) becomes approximately linear. The intensity Ppdn of an interference light, between propagation lights in CW and CCW directions in an optical fiber loop (13), having a difference non-reciprocal phase bias is measured not less than two times. A phase difference theta is then calculated based on the intensity Ppdn in the linear sections.
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