Embedded optical sensor capable of strain and temperature measurement using a single diffraction grating
US5399854A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1994 |
| Grant date | Mar 21, 1995 |
| Priority date | — |
| Expiry date | Mar 8, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K11/3206
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An embedded optical sensor has a plurality of layers 10-20 and an optical fiber 21 with a fiber grating 28, disposed between the layers 14,16. The layers 10-20 comprise filaments 22 and resin 24 which have different thermal expansion coefficients and the filaments 22 are oriented so as to create unequal transverse residual stresses that act through the geometry of a resin-rich region that surrounds on the grating 28 in the fiber 21. The unequal transverse residual stresses cause birefringence in the grating 28, thereby causing the grating 28 to reflect light 32 having two wavelengths with a predetermined separation, each along a different polarization axis. The wavelength separation and average wavelength between such separation have different sensitivities to temperature and strain, thereby allowing independent temperature and strain measurements using only a single grating. The birefringence is maximized when the filaments 22 of the adjacent layers 10,12 are oriented at 90 degrees with respect to the longitudinal (Z-axis) of the fiber 21.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.