Remote Sensing

• US 20120017687A1
• Filed: 03/30/2010
• Published: 01/26/2012
• Est. Priority Date: 04/07/2009
• Status: Active Grant

• Current Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Hill, David John, Davis, Richard John
• Granted Patent: US 8,661,907 B2
• Time in Patent Office: Days
• US Class Current: 73/655
• CPC Class Codes: G01D 5/35358 using backscattering to detect the measured quantity
• CPC Class Codes: G01D 5/35383 using multiple sensor devices using multiplexing techniques

Abstract

A plurality of sensors output information into a distributed acoustic sensing (DAS) system via acousto-mechanical signals. The sensors are coupled to the optic fibre at the centre of the DAS system indirectly, the acousto-mechanical signal being transmitted via an intermediary body, such as the ground or a conduit.

Claims

1. A sensor system comprising:

an elongate optic fibre;

an interrogation unit adapted to provide distributed acoustic sensing along a length of said optic fibre; and

one or more sensor devices coupled to said optic fibre, each said device including a sensor element adapted to sense an external stimulus and an actuator adapted to produce an acousto-mechanical output signal representative of said sensed data, said acousto-mechanical output being capable of detection by said interrogation unit;

wherein said acoustic coupling is by indirect coupling of the sensor element to the optic fibre.

2. A sensor system according to claim 1, wherein said one or more sensor devices and said optic fibre are acoustically coupled via an intermediate body.

3. A sensor system according to claim 1, wherein said optic fibre is located underground in use, and wherein said one or more sensor devices is acoustically coupled to said optic fibre through the ground.

4. A sensor system according to claim 1, wherein said optic fibre is mounted to a conduit in use, and wherein said one or more sensor devices is acoustically coupled to said optic fibre through said conduit.

5. A sensor system according to claim 1, wherein said one or more sensor devices and said optic fibre are physically separated by greater than or equal to 200 mm.

6. A sensor system according to claim 1, wherein said interrogation unit detects radiation backscattered from one or more input pulses.

7. A sensor system according to claim 1 wherein said one or more sensor devices includes a dedicated power source.

8. A sensor system according to claim 1 wherein said one or more sensor devices includes a power converter for harvesting environmental energy.

9. A sensor system according to claim 1 wherein said one or more sensor devices is adapted to sense at least one of ambient light, temperature, air speed and/or direction, or moisture.

10. A sensor system according to claim 1 wherein said one or more sensor devices is adapted to measure an operating parameter of an external apparatus.

11. A sensor system according to claim 1, wherein said system includes more than one sensor device, and said devices are adapted to sense different external stimuli.

13. A sensor system according to claim 1 wherein said optic fibre is located underground in use, and wherein said one or more sensor devices is acoustically coupled to said optic fibre through the ground;

wherein said one or more sensor devices and said optic fibre are physically separated by greater than or equal to 200 mm; and

wherein said interrogation unit detects radiation backscattered from one or more input pulses.

14. A sensor system according to claim 1 wherein said optic fibre is mounted to a conduit in use, and wherein said one or more sensor devices is acoustically coupled to said optic fibre through said conduit;

wherein said one or more sensor devices and said optic fibre are physically separated by greater than or equal to 200 mm; and

wherein said interrogation unit detects radiation backscattered from one or more input pulses.

12. A method of sensing comprising:

operating an interrogation unit to provide distributed acoustic sensing along an elongate optic fibre;

coupling at least one sensor device to said optic fibre at a desired location along the length of the fibre;

measuring an external parameter at said desired location with said sensor device;

coding said measurement value into an acousto-mechanical signal;

transmitting said signal acoustically through an intermediary body to said optic fibre, and detecting said acousto-mechanical signal at said interrogation unit, and decoding to derive said measurement value.