Method and apparatus for interrogation of birefringent FBG sensors
US6788418B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 23, 2002 |
| Grant date | Sep 7, 2004 |
| Priority date | — |
| Expiry date | Aug 4, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/35387
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for measurements of the orthogonally polarized minimum and maximum Bragg wavelengths of one of several birefringent fiber Bragg grate FBG sensors, and alternatively a method for eliminating errors in FBG sensor measurements caused by undesired grating birefringence, using an FBG wavelength interrogation apparatus, where the light from a polarized wavelength swept narrowband source (1) is passed through an electrically controllable polarization controller (2), operated in either a scanning mode or a tracking mode to find the two orthogonally polarized reflection spectra of the birefringent FBGs (6) with corresponding minimum and maximum Bragg wavelength &ggr;nx and &ggr;nx, where a low-birefringent reference FBG with known wavelength (5) and a low-birefringent fixed Fabry-Perod interferometer (8), generating frequency equidistant peaks are used in combination to provide accurate and readable wavelength measurements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.