High intensity fabry-perot sensor

• US 7,782,465 B2
• Filed: 02/04/2009
• Issued: 08/24/2010
• Est. Priority Date: 03/16/2005
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Lopushansky, Richard L., Gillham, Frederick J., Jeffers, Larry A., Gibler, William N.
• Primary Examiner(s): Lyons; Michael A
• Application Number:
  US12/365,700
• Publication Number:
  US 20090207417A1
• Time in Patent Office: 566 Days
• Field of Search: 356/35.5, 356/454, 356/480, 356/519, 250/227.19, 250/227.27, 359/578
• US Class Current: 356/480
• CPC Class Codes: G01B 2290/25 Fabry-Perot in interferometer, e.g. etalon, cavity
• CPC Class Codes: G01B 9/02068 Auto-alignment of optical elements
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01D 5/35312 using a Fabry Perot
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: G02B 6/322 and having centering means being part of the lens for the self-positioning of the lightguide at the focal point, e.g. holes, wells, indents, nibs
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence

Abstract

A method and apparatus for detecting seismic vibrations using a series of MEMS units, with each MEMS unit including an interferometer is described. The interferometers on the MEMS units receive and modulate light from two differing wavelengths by way of a multiplexing scheme involving the use of Bragg gratings and light circulators, and an optoelectronic processor receives and processes the modulated light to discern vibrational movement of the system, which in turn allows for monitoring and calculation of a specified environmental parameter, such as seismic activity, temperature or pressure.

Claims

1. A sensor assembly comprising:

an optical fiber having an optical axis;

a lens in optical communication with said optical fiber, said lens having an optical axis and said lens capable of transmitting a beam of light;

a reflective surface, said reflective surface spaced from said lens such that said beam of light transmitted from said lens is capable of reflecting from said reflective surface back to said lens; and

an alignment device capable of aligning said beam of light transmitted from said lens substantially perpendicular with said reflective surface.

2. The sensor assembly of claim 1, further comprising a transparent window with a partially reflective surface, wherein said partially reflective surface of said window is substantially parallel with and is separated by a gap from said reflective surface, said optically transparent window and said reflective surface forming a Fabry-Perot sensor.

3. The sensor assembly of claim 2, wherein said lens comprises at least one of:

a ball lens;

a graded index lens;

a lens that focuses light; and

a lens that collimates lights.

4. The sensor assembly of claim 3, further comprising a ferrule encasing said optical fiber, said ferrule aligning said optical axis of said optical fiber with said optical axis of said lens.

5. The sensor assembly of claim 3, wherein said ball lens is attached to said optical fiber to align said optical axis of said optical fiber with said optical axis of said lens.

6. The sensor assembly of claim 5, wherein said ball lens is attached to said optical fiber by melting or bonding said ball lens to said optical fiber.

7. The sensor assembly of claim 4, wherein said ball lens is not attached to said optical fiber.

8. The sensor assembly of claim 1, wherein said alignment device comprises:

a body having a socket aperture;

a ball rotatably positioned in said socket aperture;

wherein at least a portion of said optical fiber is positioned within said ball.

9. The sensor assembly of claim 8, wherein said ball is rotatable to align said beam of light transmitted from said lens substantially perpendicular with said reflective surface.

10. The sensor assembly of claim 1, wherein said alignment device comprises a wedge shaped window located between said lens and said reflective surface.

11. The sensor assembly of claim 1, wherein said alignment device comprises a wedge shaped spacer located between said lens and said reflective surface.

12. The sensor assembly of claim 1, wherein said alignment device comprises a transducer body having an axis and an end surface, said end surface machined at an angle relative to said transducer body axis to align said beam of light transmitted from said lens substantially perpendicular with said reflective surface.

13. The sensor assembly of claim 1, wherein said reflective surface is a diaphragm.

14. The sensor assembly of claim 13, wherein said diaphragm comprises at least one of:

a flat diaphragm;

a mesa diaphragm;

a plug diaphragm; and

a bellows diaphragm.

15. The sensor assembly of claim 13, wherein said diaphragm has a dielectric reflective surface.

16. The sensor assembly of claim 15, wherein said diaphragm comprises a mesa diaphragm, said mesa diaphragm comprising a circular groove substantially surrounding said dielectric reflective surface.

17. The sensor assembly of claim 13, wherein said diaphragm has a flat or a concave reflective surface.

18. The sensor assembly of claim 1, further comprising a flexible tube encasing at least a portion of said optical fiber to form a flexible transducer.

19. A Fabry-Perot sensor assembly comprising:

an optical fiber;

a ball lens in optical communication with said optical fiber said ball lens capable of transmitting a beam of light;

a window having a first surface and a second surface;

a diaphragm spaced from and parallel to said second surface of said window, said diaphragm having a partially reflective surface; and

an alignment device capable of aligning said beam of light transmitted from said ball lens substantially perpendicular with said partially reflective dielectric coating of said diaphragm.

20. The Fabry-Perot sensor assembly of claim 19, wherein said ball lens is attached to said optical fiber.