DIRECT MEASUREMENT OF BRILLOUIN FREQUENCY IN DISTRIBUTED OPTICAL SENSING SYSTEMS

Title:

DIRECT MEASUREMENT OF BRILLOUIN FREQUENCY IN DISTRIBUTED OPTICAL SENSING SYSTEMS

Document Type and Number:

WIPO Patent Application WO2005106396

Kind Code:

A3

Abstract:

An optical sensing system uses light scattered from a sensing fibre to sense conditions along the fibre, and has a receiver with a frequency to amplitude converter to obtain a frequency of a Brillouin component of the received scattered light, to deduce the conditions. This converter can avoid time consuming scanning of frequencies to obtain the Brillouin frequency spectrum, and avoids the heavy processing load of deducing a peak or average frequency from the spectrum. The converter can be implemented in the optical domain using a grating or interferometer, or in the electrical domain using a diplexer or electrical interferometer. It can generate complementary signals, having opposite signs, a ratio of these signals representing the frequency. This can avoid sensitivity to amplitude changes in the received scattered signals and provide common mode rejection of noise.

Inventors:

WATLEY DANIEL ANDREW (GB)
FARHADIROUSHAN MAHMOUD (GB)
SHAW BARRY JOHN (GB)

Application Number:

PCT/GB2005/050040

Publication Date:

January 19, 2006

Filing Date:

March 22, 2005

Export Citation:

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Assignee:

SENSORNET LTD (GB)
WATLEY DANIEL ANDREW (GB)
FARHADIROUSHAN MAHMOUD (GB)
SHAW BARRY JOHN (GB)

International Classes:

E21B47/10; G01D5/353; G01K11/32; G01M5/00; G01M11/08; (IPC1-7): G01D5/353

Foreign References:

US20020040963A1	2002-04-11
US20010050768A1	2001-12-13
US6380534B1	2002-04-30
US20020041722A1	2002-04-11

Other References: