EP0144509A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Fiber optic interferometer transducer
Assignee: Polaroid Corp
•
Filing: 1984-07-13
•
Granted: —
•
Expires: 2004-07-13
Abstract
Abstract A sensor or transducer having a dual path optical fiber, such as a single mode, two polarization state, waveguide fiber, utilizes the relative change in propagation constant of the paths to sense and transduce an applied force to an interference variation and ultimately an electrical signal. In this arrangement, in-phase light is introduced to both polarized states or paths in the fiber and transmitted therealong past a stress area of birefringement inducing force and ultimately combined, thereby producing in the combined beam a variation in interference which is related to the applied force. Specific structures are provided for converting isotropic forces such as pressure and temperature to anisotropic forces on the fiber to thereby produce birefringement and to also magnify the latter effect.
Inventors
- 👤 John Wilbur Hicks, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 17:03
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/344; G01L; G01L1/00; G01L1/24; G01L1/242; G01L1/243
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
74 words
A sensor comprising: an optical fiber having at least two different optical paths, the propagation constant of at least one of the paths being variable in response to an environmental factor applied to the fiber; means for introducing light energy of fixed phase relationship into both paths; means for combining the light energy transmitted along each path to provide interference therebetween; and means for evaluating the interference and for providing an output related thereto.
Claim 2
Dependent Claim
74 words
A sensor comprising: an optical fiber having at least two different optical paths, the propagation constant of at least one of the paths being variable in response to an environmental factor applied to the fiber; means for introducing light energy of fixed phase relationship into both paths; means for combining the light energy transmitted along each path to provide interference therebetween; and means for evaluating the interference and for providing an output related thereto.
Claim 3
Dependent Claim
21 words
The sensor of claim 1 wherein the light energy is introduced to both paths at one end of the optical fiber.
Claim 4
Dependent Claim
23 words
The sensor of claim 2 wherein the means for combining the light energy is located at the other end of the optical fiber.
Claim 5
Dependent Claim
42 words
The sensor of claim 2 including means adjoining the other end of the fiber for reflecting the light energy back toward the one end, the light introducing means being located at the one end, and including means for combining the reflected energy.
Claim 6
Dependent Claim
38 words
The sensor of claim 4 wherein the introducing means includes a polarizer for introducing light to the paths, the polarizer operating as an analyzer for light reflected back from the other end to combine the light for interference.
Claim 7
Dependent Claim
36 words
The sensor of claim 1 wherein the means for introducing the light energy includes a source of light energy and a plane polarizer oriented with respect to the paths to introduce light energy into each path.
Claim 8
Dependent Claim
25 words
The sensor of claim 1 wherein the optical fiber is a single mode optical waveguide fiber with two polarization states which define the different paths.
Claim 9
Dependent Claim
31 words
The sensor of claim 7 wherein the combining means comprises means for polarizing the light energy transmitted along both paths to a plane polarized state at an angle to both paths.
Claim 10
Dependent Claim
38 words
The sensor of claim 7 wherein the introducing means includes a plane polarizer illuminated with coherent radiation, the polarization plane of the polarizer being oriented at an angle to both paths to introduce light energy into each path.
Claim 11
Dependent Claim
21 words
The sensor of claim 9 wherein the polarizer is oriented to introduce approximately equal amounts of light energy into each paths.
Claim 12
Dependent Claim
41 words
The sensor of claim 1 wherein the optical fiber comprises a tubing member having an optical fiber arrangement extending longitudinally along the tubing in a wall section thereof to amplify the birefringant effect of the environmental factor on the fiber arrangement.
Claim 13
Dependent Claim
28 words
The sensor of claim 11 wherein the tubing is elongated in one of its cross-sectional dimensions, and the fiber is carried within one of the laterally elongated walls.
Claim 14
Dependent Claim
33 words
The sensor of claim 1, wherein the optical fiber is embedded in a structural member adapted for amplifying the effect on the propagation constant of the environmental factor applied to the structural member.
Claim 15
Dependent Claim
26 words
The sensor of claim 13 wherein the structural member is adapted to convert an isotropic stress on the member to an anisotropic stress on the fiber.
Claim 16
Dependent Claim
50 words
The sensor of claim 14 wherein the fiber is embedded within a portion of the structural member having a thermal coefficient of expansion different from other portions so that the structural member produces birefringing stress on the fiber under thermal variations applied to the member thereby providing a temperature transducer.
Claim 17
Dependent Claim
28 words
The sensor of claim 15 wherein the member is an elongated rod having an outer sleeve forming the one portion and an inner cylinder forming the other portion.
Claim 18
Dependent Claim
35 words
The sensor of claim 15 wherein the member comprises an elongated hollow tube member having a plate portion extending across its interior, the plate forming the one member and the tube forming the other member.
Claim 19
Dependent Claim
23 words
The sensor of claim 12 wherein the tubing is elliptical in cross-section and the one wall extends along one axis of the ellipse.
Claim 20
Dependent Claim
32 words
The sensor of claim 12 wherein the fiber is carried within the opening of and extended longitudinally along the tubing in contact with opposing walls of the narrow dimension of the cross-section.
Claim 21
Dependent Claim
53 words
The sensor of claim 13 wherein the fiber and the structural member include an elongated glass cylinder having a glass fiber optics core extending longitudinally therein at the surface thereof, with an overlying layer of birefringent sensitive material, the cylinder and the layer having indices of refraction lower than that of the core.
Claim 22
Dependent Claim
21 words
The sensor of claim 20 wherein the thickness of the layer is two to three times the diameter of the core.
Claim 23
Dependent Claim
17 words
The sensor of claim 20 wherein the layer has an index of refraction lower than the cylinder.
Claim 24
Dependent Claim
11 words
The sensor of claim 20 wherein the layer is plastic material.
Claim 25
Dependent Claim
36 words
The sensor of claim 20 wherein the structural member is coiled about a solid mandrel with the fiber bearing portion adjoining the mandrel, and a flexible casing surrounds the coiled member for transmitting external pressure thereto.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.