Method and apparatus for measurements dependent on the faraday effect using polarized counter-propagating light
US5475298A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 29, 1993 |
| Grant date | Dec 12, 1995 |
| Priority date | — |
| Expiry date | Oct 29, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R15/246
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Measurements, particularly of current, using the Faraday magneto-optic effect in an optical fibre, have suffered from inaccuracy due to vibration causing linear birefringence in the fibre. Current measurement according to the method and apparatus employs an optical fibre (3) coiled round a conductor (6) carrying the current to be measured. A laser (1) launches two counter propagating light beams into the fibre by way of a beam splitter (2) and directional couplers (4,5). Polarization beam splitters (7,8) derive two pairs of orthogonally linearly polarized light beams, one from each direction of propagation. These beams are passed to detectors (10,11,12,13) having outputs coupled to a processor (14). An output signal is derived by the processor which is representative of the non-reciprocal Faraday rotation but independent of reciprocal birefringent effects, including linear birefringence due to vibration. Thus the output signal is representative of current in the conductor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.