Signal processing for a Sagnac interferometer
US7505139B2 · kind B2 · utility
Inventor
Key dates
| Filing date | Mar 6, 2007 |
| Grant date | Mar 17, 2009 |
| Priority date | — |
| Expiry date | Jun 14, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01C19/726
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Disclosed is a method and apparatus for modulating the phase difference between a pair of optical waves that exit a Sagnac interferometer, and, more particularly, one that is commonly employed as a fiber gyro, and includes a detector responsive to phase difference between the pair of waves that exit the interferometer, and a phase modulator that forms part of two control loops that are instrumental in deriving an accurate measurement of rotation rate. As disclosed herein, phase modulation applied equally to the pair of waves as they counter-propagate through the phase modulator induces modulation of the phase-difference between the two waves as they exit the interferometer. This phase difference modulation includes (i) a bias phase-difference modulation component having a selected frequency, amplitude, and waveform, (ii) a rotation-rate feedback phase-difference component that is equal in magnitude to, and opposite in sign of, the Sagnac phase difference, so that the sum thereof is controlled to be substantially zero, and (iii) a calibration feedback phase-difference modulation component that is characterized by a predetermined phase difference magnitude having substantially altern…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.