Detecting a disturbance in the propagation of light in an optical waveguide
US7872736B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 3, 2005 |
| Grant date | Jan 18, 2011 |
| Priority date | — |
| Expiry date | Jul 30, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01M11/3127
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical time domain reflectometry apparatus has a laser and light modulator for producing coherent light pulses, each having two sections of higher intensity separated by a gap of lower or substantially zero intensity. As the light pulses propagate along the optical fibre, light is continuously Rayleigh backscattered by inhomogeneities of the optical fibre. A photodetector generates backscatter signals representing the intensity of light Rayleigh backscattered in the optical fibre as each light pulse travels along the optical fibre. The PC uses these backscatter signals to derive a difference signal representing a change dI in intensity between signals generated from two successive pulses. The PC then calculates the Root Mean Square (RMS) of the difference signal averaged over the interval between the two sections of the light pulses. Next, the PC averages the backscatter signal generated from the first of the pulses over the same interval and normalises the RMS difference signal using the averaged signal to obtain a compensated difference signal that depends only on differences in the rate of change of phase of light of the light pulses as they travelled along the waveguide. Th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.