Fiber optic bending and positioning sensor including a light emission surface formed on a portion of a light guide

• US 5,321,257 A
• Filed: 07/20/1992
• Issued: 06/14/1994
• Est. Priority Date: 07/31/1991
• Status: Expired due to Fees

• Current Assignee: 059312 N.B. Inc.
• Original Assignee: Lee A. Danisch
• Inventors: Danisch, Lee A.
• Primary Examiner(s): Berman, Jack I.
• Assistant Examiner(s): Beyer, James
• Application Number:
  US07/915,283
• Time in Patent Office: 694 Days
• Field of Search: 250/227.16, 250/227.14, 385/12, 385/13
• US Class Current: 250/227.16
• CPC Class Codes: A61B 1/009 with bending or curvature detection of the insertion part
• CPC Class Codes: G01D 5/35345 using Amplitude variations to detect the measured quantity
• CPC Class Codes: G01D 5/35377 Means for amplifying or modifying the measured quantity
• CPC Class Codes: G02B 6/02066 Gratings having a surface relief structure, e.g. repetitive variation in diameter of core or cladding
• CPC Class Codes: G02B 6/2852 using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)

Abstract

A bending, and position, sensor is composed of a fiber optic or light wave guide, for attachment to the member which is to be bent, or displaced. Light is injected at one end and detected at the other end. Bending of the fiber results in light loss through a surface strip or band, along one side of the fiber, this loss being detected. The loss of light detection is used to produce indication of bending or displacement. Two or more light guides can be oriented to give indication of direction of bending, or displacement.

Claims

1. A fiber optic bending, and positioning, sensor comprising a fiber optic guide having a light emission surface extending in a thin band on a side of the fiber for at least part of its length, said light emission surface covered by a coating of light absorbent material.

2. A sensor as claimed in claim 1, said light emission surface comprising a textured surface.

3. A sensor as claimed in claim 2, said textured surface comprising a serrated surface, the serrations extending transversely of the axis of the light guide.

4. A sensor as claimed in claim 1, including means for injecting a light beam into one end of said light guide and means for detecting said light beam at the other end of said light guide.

5. A sensor as claimed in claim 4, including means for measuring the difference in intensity of said light beam between said one end and said other end of said light guide.

6. A sensor as claimed in claim 5, including display means for indicating any said difference in intensity of said light beam as a bending or displacement of said light guide.

7. A sensor a claimed in claim 1, including a further fiber optic light guide positioned alongside said fiber optic light guide, said further light guide having an unbroken cladding layer and forming a reference light guide.

8. A sensor as claimed in claim 1, comprising a plurality of said fiber optic light guides, each having a light emission surface extending in a thin band on a side of the fiber, said thin bands oriented in different directions, at predetermined angles relative to each other.

9. A sensor as claimed in claim 1, comprising three fiber optic guides, extending alongside each other in a parallel array, each light guide having a light emission surface extending in a thin band on a side of the fiber for at least part of its length, said thin bands oriented at approximately 120°

to each other.

10. A sensor as claimed in claim 5, said measuring means adapted to indicate bending of a member to which the sensor is attached.

11. A sensor as claimed in claim 5, said measuring means adapted to indicate displacement of one end of a member, to which the sensor is attached, relative to its other end.

12. A method of sensing bending, and displacement, of an elongate member, comprising attaching a fiber optic light guide to said member, said light guide having a light emission surface extending in a thin band on a side of the fiber at least part of its length, said light guide extending along said member;

injecting a light beam into one end of said light guide, detecting said light beam at the other end of said light guides, and measuring the difference in intensity of said light beam between said one end and said other end, indicating bending, or displacement, of said member.

13. The method of claim 12, including attaching a plurality of fiber optic light guides to said elongate member, each having a light emission surface extending in a thin band, said bands oriented at predetermined angles to each other.

14. The method as claimed in claim 13, including three fiber optic light guides, said bands oriented at about 120°

to each other.

15. The method as claimed in claim 12, including attaching a further fiber optic light guide alongside said fiber optic light guide, said further fiber optic light guide acting as a reference light guide.

16. Apparatus for sensing, and indicating, bending or displacement of a member, comprising:

a fiber optic wave guide having a light emission surface extending in a thin band on a side of the fiber, means for mounting said wave guide on said member, means for injecting a light beam into one end of said wave guide;

means for detecting transmitted light at the other end of said wave guide; and

means for measuring the difference in intensity of said light beam between said one end and said other end of said wave guide.

17. A sensor as claimed in claim 16, said light emission surface comprising a textured surface.

18. A sensor as claimed in claim 17, said textured surface comprising a serrated surface, the serrations extending transversely of the axis of the light guide.

19. A sensor as claimed in claim 16, including display means for indicating any said difference in intensity of said light beam as a bending or displacement of said light guide.

20. A sensor as claimed in claim 16, including a further fiber optic guide positioned alongside said fiber light guide, said further light guide having an unbroken cladding layer and forming a reference light guide.

21. A sensor as claimed in claim 16, comprising a plurality of said fiber optic light guides, each having a light emission surface extending in a thin band on a side of the fiber, said thin bands oriented in different directions, at predetermined angles relative to each other, means for injecting a light beam into one end of each light guide, means for detecting transmitted light at the other end of each light guide, and means for measuring the difference in intensity of said light beams between said one end and said other end of each light guide.

22. A sensor as claimed in claim 21, comprising three fiber optic light guides, extending alongside each other in a parallel array, each wave light having a light emission surface extending in a thin band on a side of the fiber for at least part of its length, said thin bands oriented at approximately 120°

to each other.

23. A sensor as claimed in claim 16, said measuring means adapted to indicate bending of a member to which the sensor is attached.

24. A sensor as claimed in claim 16, said measuring means adapted to indicate displacement of one end of a member, to which the sensor is attached, relative to its other end.

25. A sensor as claimed in claim 16, including a layer of light absorbent material on said light emission surface.