Composite integrity monitoring
US4983034A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 13, 1989 |
| Grant date | Jan 8, 1991 |
| Priority date | — |
| Expiry date | Feb 13, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L1/242
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical frequency domain distributed strain sensor for determining the strain distribution along an optical fiber includes an optical source that provides a polarization controlled optical interrogation signal having a frequency that varies in a recurring linear manner. The interrogation signal is injected into a sensor fiber embedded within a composite structure that places the fiber under strain. A portion of the interrogation signal is backscattered from the sensing fiber as a consequence of the strain experienced by the fiber and is mixed with a reference signal to produce beat frequency signals. The frequency of the beat signals is directly related the to position of backscatter in the sensing fiber while the amplitude of each beat frequency signal is directly related to the integrated strain-induced birefringence up to the backscatter point. An in-line fiber polarizer and an associated controllable polarizer control the polarization state of the interrogation signal in the sensor fiber to provide zero point sensitivity compensation and controllable testing for ambiguous strain points.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.