Packaged optical sensors on the side of optical fibres

• US 20030231818A1
• Filed: 02/19/2003
• Published: 12/18/2003
• Est. Priority Date: 02/20/2002
• Status: Active Grant

• Current Assignee: Institut national d'optique
• Original Assignee: Institut national d'optique
• Inventors: Frechette, Julie, Cantin, Daniel, Levesque, Marc, Cournoyer, Alain, Plante, Sylvain
• Granted Patent: US 7,209,605 B2
• Time in Patent Office: Days
• US Class Current: 385/12
• CPC Class Codes: G01D 5/35383 using multiple sensor devices using multiplexing techniques
• CPC Class Codes: G01K 11/3206 at discrete locations in the fibre, e.g. using Bragg scattering
• CPC Class Codes: G01N 2021/6484 Optical fibres
• CPC Class Codes: G01N 21/648 using evanescent coupling or surface plasmon coupling for the excitation of fluorescence
• CPC Class Codes: G01N 21/7703 using reagent-clad optical fibres or optical waveguides using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B

Abstract

The present invention concerns an optical sensor located on the side of an optical fibre. An optical fibre having two opposite ends, a core and a cladding and at least one sensing area is disclosed. Each of the sensing areas is located between the two opposite ends and each has a longitudinal and radial portion of the fibre that has been removed and replaced by a sensing material. The luminescent light is thus representative of a parameter to be measured, such as temperature. Placing the sensing material in a side portion of the fibre increases the sensitivity of the sensor, particularly when it comes to temperature measurement in vivo.

Claims

1. An optical sensor comprising an optical fibre for conveying a light beam, said optical fibre being provided with a first end for receiving said light beam and a second end opposed thereto, a core and a cladding surrounding said core, and at least one claddingless portion having a longitudinal and a radial extent, each of said at least one claddingless portion defining a shaped cavity extending in said optical fibre between said two opposite ends, said optical sensor further comprising a sensing material extending in each of said cavities for forming a sensing area therein in contact relationship with said core.

2. The optical sensor according to claim 1, wherein at least one of said cavities extends radially inside said core.

3. The optical sensor according to claim 1, wherein said optical fibre has a predetermined permanent shape for projecting at least one of said at least one sensing area outwardly.

4. The optical sensor according to claim 1, wherein each of said at least one sensing area extends in a longitudinal alignment relationship with each others, each of said at least one sensing area being separated to each others by a predetermined distance.

5. The optical sensor according to claim 1, wherein each of said at least one sensing area extends in a radial alignment relationship with each others around said optical fibre, each of said at least one sensing area being separated to each others by a predetermined distance.

6. The optical sensor according to claim 1, wherein said core having a refractive index, said sensing material has a refractive index greater than or equal to the refractive index of the core.

7. The optical sensor according to claim 1, wherein the sensing material is a luminescent material.

8. The optical sensor according to claim 1, wherein the sensing material has spectral optical properties sensitive to a concentration of a chemical or a biochemical compound.

9. The optical sensor according to claim 1, wherein the sensing material has spectral optical properties sensitive to a presence of a chemical or a biochemical compound.

10. The optical sensor according to claim 1, wherein the sensing material is a transparent material.

11. The optical sensor according to claim 1, further comprising a thermally conductive coating surrounding said sensing material.

12. The optical sensor according to claim 1, further comprising a reflecting film extending on said sensing material.

13. The optical sensor according to claim 1, wherein said cavity is formed by a chemical etching process.

14. The optical sensor according to claim 1, wherein said cavity is formed by laser processing.

15. The optical sensor according to claim 1, wherein said optical fibre is a multimode optical fibre.

16. The optical sensor according to claim 1, wherein the second end of the optical fibre is provided with an index matching material.

17. The optical sensor according to claim 1, further comprising a reflector extending radially inside said optical fibre between the sensing area and the second end of the optical fibre, said reflector extending closed to the sensing area.

18. The optical sensor according to claim 17, wherein said reflector extends angularly inside said fibre.

19. The optical sensor according to claim 17, wherein said reflector is a fibre Bragg grating.

20. An optical sensing system comprising:

at least one optical sensor, each comprising an optical fibre for conveying a light beam, said optical fibre being provided with a first end for receiving said light beam and a second end opposed thereto, a core and a cladding surrounding said core, and at least one claddingless portion having a longitudinal and a radial extent, each of said at least one claddingless portion defining a shaped cavity extending in said optical fibre between said two opposite ends, said optical sensor further comprising a sensing material extending in each of said cavities for forming a sensing area therein in contact relationship with said core;

a light source for injecting light into the first end of the optical fibre of each of said at least one optical sensor;

a detector operatively connected to one of said ends of said optical fibre of each of said at least one optical sensor for detecting light coming from each of said sensing areas; and

an analyser operatively connected to said detector for analysing light coming from each of said sensing areas.

21. An optical sensing system according to claim 20, wherein said system is a temperature sensing system.

22. An optical sensing system according to claim 20, wherein said system is a pH concentration measuring system.

23. An optical sensing system according to claim 20, wherein said system is a O₂ concentration measuring system.

24. An optical sensing system according to claim 20, wherein said system is a CO₂ concentration measuring system.

25. An optical sensing system according to claim 20, wherein said system is a glucose concentration measuring system.

26. An optical sensing system according to claim 20, wherein said system is a biological tissue identifying system.