Harmonic phase modulation error reducer
US5457532A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 1994 |
| Grant date | Oct 10, 1995 |
| Priority date | — |
| Expiry date | May 31, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/4457
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A rotation sensor for sensing rotation, particularly about an axis of a coiled optical fiber, wherein the coiled optical fiber has with light waves propagating in opposite directions in the coiled optical fiber, the phase relationship of the counter-propagating light waves providing a basis for indicating rotation of the sensor. A portion of the coiled optical fiber is a part of and affected by a bias optical phase modulator which causes a varying phase relationship between the light waves at a fundamental frequency. However, the varying phase relation ship has at least one harmonic which is due to mechanical vibration of the optical fiber that is a part of the modulator. This harmonic contributes to an erroneous indication of rotation. The amplitude of such harmonic is reduced by lowering the Q of the resonating fiber. This is effected by applying a damping material to the optical fiber and a portion of the modulator. A photodetector detects the counter-propagating waves and sends a corresponding electrical signal on to a signal component selection device that provides an indication of sensed rotation, including error due to the mechanically resonating optical fiber of the modulat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.