PURPOSE: To eliminate errors due to the fluctuation in amount of light of a light source and the fluctuation in a polarization plane in an optical fiber, by detecting Sagnac phase difference not by the intensity of interference light but by direct phase comparison.
CONSTITUTION: The first light beam from a light emitting device 1 is inputted to a polarization beam splitter through a collimate lens. The P polarized component is inputted to an optical fiber loop 6 through a polarizer 4b and a coupling lens 5b. The S polarization component is inputted to the optical fiber loop 6 through a polarizer 4a and a coupling lens 5a. The light beams outputted from the optical fiber loop 6 are guided to a frequency hift element 8 through a cross- polarization separating optical element 7a and undergo Bragg diffraction by the element 8. The beam are guided to a detector 11 through the cross-polarization coupling lement 7b, a polarizer 9, and an analyzer 10. A driving signal 13 for the frequency shift element 8 is controlled so that the phase difference between the signal and a detected signal 19 from an ultasonic wave detector 8b becomes constant.
HIRANO TAKASHI
YASUI SATOSHI
TAKAGUCHI TAKASHI
ISHIBASHI AKIHIRO
BOEICHO GIJUTSU KENKYU HONBUCH
| JPS5918416A | 1984-01-30 |
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