Interferometric method and apparatus for measuring physical parameters
US7548319B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 20, 2004 |
| Grant date | Jun 16, 2009 |
| Priority date | — |
| Expiry date | May 7, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L1/246
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of measuring a selected physical parameter at a location within a region of interest comprises the steps of: launching optical pulses at a plurality of preselected interrogation wavelengths into an optical fiber (1) deployed along the region of interest, reflectors (20, 21, 2n) being arrayed along the optical fiber (1) to form an array (9) of sensor elements, the optical path length between the said reflectors (2) being dependent upon the selected parameter; detecting the returned optical interference signal for each of the preselected wavelengths; determining from the optical interference signal the absolute optical path length (L) between two reflectors (2) at the said location; and determining from the absolute optical path length (L) the value of the selected parameter at the said location; wherein the step of determining the absolute optical path length (L) comprises carrying out a process in which the phase difference between the interference signals for a pair of the preselected wavelengths is estimated using an estimated value for the optical path length (L), the estimated phase difference is used to estimate the phase at each of those wavelengths, and the phase th…
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