DISTRIBUTED DEVICE FOR THE DETECTION OF A SUBSTANCE

• US 20190033202A1
• Filed: 01/24/2017
• Published: 01/31/2019
• Est. Priority Date: 01/26/2016
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: CINA, Salvatore, MOUREY, Bruno
• Granted Patent: US 10,641,701 B2
• Time in Patent Office: Days
• CPC Class Codes: E21B 47/113 using electrical indications; using light radiations
• CPC Class Codes: G01N 2021/1704 in gases
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/9009 Non-optical constructional details affecting optical inspection, e.g. cleaning mechanisms for optical parts, vibration reduction
• CPC Class Codes: G01N 2201/0846 Fibre interface with sample, e.g. for spatial resolution
• CPC Class Codes: G02B 6/0208 characterised by their structure, wavelength response G02B6/02114, G02B6/02171, G02B6/02195 take precedence; multiple layer cores or claddings G02B6/036, protective coverings G02B6/4429

Abstract

A distributed device for the detection of a substance is disclosed, comprising: a distributed optical excitation source (21) including a first optical fiber (22) having a plurality of extraction regions (24), each extraction region (24) being adapted to extract part of the light carried by the first optical fiber (22) from said fiber; and a distributed acoustic sensor (25) including a second optical fiber (26).

Claims

1. A distributed substance detection device, comprising:

a distributed optical excitation source comprising;

a first optical fiber provided with a plurality of extraction regions, each extraction region being capable of extracting from the first optical fiber part of the light conveyed by the fiber;

a first light source capable of injecting into the first optical fiber a first light signal at an absorption wavelength of the substance to be detected; and

a control circuit capable of modulating the first light signal in intensity at an acoustic frequency; and

a distributed acoustic detector comprising;

a second optical fiber;

a second light source capable of injecting a second light signal into the second optical fiber; and

an optical detector capable of measuring a third backscattered light signal in the second optical fiber to detect and locate an acoustic vibration at the modulation frequency of the first light signal.

2. The device of claim 1, wherein the first and second optical fibers are intended to be placed in an area where the presence of said substance is desired to be detected.

3. The device of claim 1, wherein the first light source has an adjustable wavelength.

4. The device of claim 1, wherein the second optical fiber comprises a plurality of measurement regions each comprising a Bragg mirror placed on the path of the light conveyed by the second optical fiber.

5. The device of claim 1, wherein the first and second optical fibers are confounded.

6. The device of claim 1, further comprising a support having the first and second optical fibers arranged therein, the support defining a tubular cavity extending along substantially the entire length of the first and second optical fibers, said cavity being capable of confining a sample of a fluid where the possible presence of said substance is desired to be detected.

7. The device of claim 6, wherein said cavity coupled to an outer environment by a plurality of openings formed in the support.

8. The device of claim 6, wherein the first optical fiber is located in said cavity.

9. The device of claim 6, wherein said cavity comprises a plurality of nip or throat areas distributed all along its length.

10. The device of claim 1, wherein said substance to be detected is carbon dioxide or hydrogen sulfide.

11. The device of any of claim 1, wherein the first optical fiber comprises a core made of a transparent material having a first refraction index and a sheath made of a transparent material having a second refraction index, each extraction region corresponding to a portion of the first fiber comprising microstructures formed on the sheath of the fiber, capable of causing the extraction, to the outside of the first fiber, of part of the light conveyed by the fiber.

12. The device of claim 11, wherein the microstructures are disordered microstructures capable of diffusing in all directions part of the light conveyed by the first fiber.

13. The device of claim 11, wherein the microstructures are ordered microstructures defining a diffraction grating capable of deviating according to a determined angle part of the light conveyed by the first fiber.

14. The device of claim 1, wherein the extraction regions are sized so that, for a given emission power of the first light source, the light flow emitted outside of the first fiber at the level of each of the extraction regions has substantially the same intensity.