Fiber optic interferometric strain gauge assembly using an intensity ratio
US5909273A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 5, 1997 |
| Grant date | Jun 1, 1999 |
| Priority date | — |
| Expiry date | Sep 5, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L1/246
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A fiber optic interferometric strain gauge assembly includes a sensor element (1) in the form of a length of single mode optical fiber whose ends (1a) and (1b) have a peak reflectivity not exceeding 10%. This reflectivity is provided either by semi-transparent coating on the fiber ends or by the establishment of Bragg gratings within the fiber length. A laser source (2) provides a beam which is coupled into the element (1) as one arm of an interferometer. The light reflected in the interferometer whose intensity varies depending upon the degree of strain applied to the element (1) is detected and separated out into samples corresponding to the frequency of the laser source and to twice the frequency of the laser source with the two values being processed to provide both the magnitude of strain and the direction of strain in the element (1).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.