| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a sensor with an optical interference signal output as a sensor signal, using a homodyne interference system with a simple structure having no power source for a sensor part, which achieves reliable operation without need for strict working accuracy of components for use and countermeasures against thermal expansion, allowing a variable phase range for the sensor signal not to be limited within ±90 degrees. <P>SOLUTION: A periodic optical pulse is used as an input from an interferometer. A reference optical pulse has phases in a first half and in a second half differing by 90 degrees (quadrature phase), interfering with a measuring optical pulse so as to produce two interference outputs i1 and i2 differing by 90 degrees. Designating the phase difference between the reference light and the measuring light as θ, two cosine values cos θ1 and cos θ2 are calculated from the values r and s of the interference outputs of the reference light and the measuring light, so as to determine the position on a cosine curve. The angles θ1 and θ2 are thus obtained, eliminating the influence of the variation in intensity of the reference light and the variation in phase operating point. The difference in angle between the present period and the immediately preceding period are added to produce a sensor output. An optical fiber sensor allowing for a variable phase range of the sensor signal exceeding ±90 degrees (half wavelength) is thus provided. <P>COPYRIGHT: (C)2013,JPO&INPIT |
