Apparatus and method for fiber optic intrusion sensing
US5194847A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 29, 1991 |
| Grant date | Mar 16, 1993 |
| Priority date | — |
| Expiry date | Jul 29, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/186
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for sensing intrusion into a predefined perimeter comprises means for producing a coherent pulsed light, which is injected into an optical sensing fiber having a first predetermined length and positioned along the predefined perimeter. A backscattered light in response to receiving the coherent light pulses is produced and coupled into an optical receiving fiber. The backscattered light is detected by a photodetector and a signal indicative of the backscattered light is produced. An intrusion is detectable from the produced signal as indicated by a change in the backscattered light. To increase the sensitivity of the apparatus, a reference fiber and an interferometer may also be employed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.