Method and apparatus for optical sensing
US10883861B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 2016 |
| Grant date | Jan 5, 2021 |
| Priority date | — |
| Expiry date | Dec 22, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V8/16
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical fiber distributed acoustic sensor system includes weak broadband reflectors inserted periodically along the fiber. The reflectors reflect only a small proportion of the light from the DAS incident thereon back along the fiber, typically in the region of 0.001% to 0.1%, but preferably around 0.01% reflectivity per reflector. In addition, to allow for temperate compensation to ensure that the same reflectivity is obtained if the temperature changes, the reflection bandwidth is relatively broadband. In some embodiments the reflectors are formed from a series of fiber Bragg gratings, each with a different center reflecting frequency, the reflecting frequencies and bandwidths of the gratings being selected to provide the broadband reflection. A chirped grating may also be used to provide the same effect. In preferred embodiments, the reflectors are spaced at half the gauge length i.e. the desired spatial resolution of the optical fiber DAS.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.