Integrated optics rotation sensor

• US 6,259,089 B1
• Filed: 05/15/1998
• Issued: 07/10/2001
• Est. Priority Date: 05/15/1998
• Status: Expired due to Fees

• Current Assignee: Rice Systems Incorporated
• Original Assignee: Rice Systems Incorporated
• Inventors: Fitzpatrick, Colleen, Vali, Victor, Youmans, Bruce
• Primary Examiner(s): Lee, John R.
• Application Number:
  US09/079,581
• Time in Patent Office: 1,152 Days
• Field of Search: 250/227.11, 250/227.12, 250/227.14, 250/227.19, 250/231.1, 250/231.12, 356/350, 356/349, 356/345, 356/459, 356/460, 356/461, 356/465, 356/466
• US Class Current: 250/231.12
• CPC Class Codes: G01C 19/722 of the mechanical construction

Abstract

A gyroscope which utilizes light waves to sense motion in the plane of the substrate. The gyroscope has a primary optical waveguide which is adapted to pass light from a single light source through the primary optical waveguide in both directions. The light exiting from each end of the primary optical waveguide is withdrawn and passed through two dedicated waveguides (one dedicated waveguide for each end of the primary optical waveguide). Preferably, these two dedicated waveguides have differing times for light travel such that one of the dedicated waveguides emits its light one-quarter wavelength behind the other dedicated waveguide. The light being emitted from each dedicated waveguide is then combined permitting a sensor to monitor any shifts between the two light signals as a monitor to motion of the primary optical waveguide.

Claims

1. A gyroscope comprising:

a) an optical source;

b) a primary optical waveguide having,

1) an extended optical waveguide having a first end and a second end, and,

2) a primary beamsplitter adapted to communicate light from said optical source to the first end and the second end of said extended optical waveguide; and

,

c) a sensing system having,

1) a first beamsplitter interposed between said primary beamsplitter and the first end of said extended waveguide, said first beamsplitter adapted to withdraw light emitting from the first end of said extended optical waveguide,

2) a first optical waveguide having a first end receiving light from said first beamsplitter,

3) a second beamsplitter interposed between said primary beamsplitter and the second end of said extended waveguide, said second beamsplitter adapted to withdraw light emitting from the second end of said extended optical waveguide,

4) a second optical waveguide having a first end receiving light from said second beamsplitter, and,

5) a beam combiner adapted to receive light from a second end of said first optical waveguide and a second end of said second optical waveguide and generating a combined optical signal therefrom; and

,

d) a detector being responsive to said combined optical signal.

2. The gyroscope according to claim 1, further including:

a) a first light intensity monitor;

b) a third beamsplitter positioned at a first end of said extended optical waveguide and communicating light thereto and to the first intensity monitor;

c) a second light intensity monitor; and

,

b) a fourth beamsplitter positioned at a second end of said extended optical waveguide and communicating light thereto and to the second intensity monitor.

3. The gyroscope according to claim 1, wherein said first optical waveguide of said sensing system has a light transmittal time greater than a light transmittal time of said second optical waveguide of said sensing system.

4. The gyroscope according to claim 3, wherein said first optical waveguide of said sensing system is longer than said second optical waveguide of said sensing system.

5. The gyroscope according to claim 4,

a) where said optical source produces light at a perdefined wavelength;

and,

b) wherein said first optical waveguide of said sensing system is approximately one quarter wavelength longer than said second optical waveguide of said sensing system.

6. The gyroscope according to claim 3, wherein a portion of said first optical waveguide of said sensing system is treated to increase light transmittal time therein.

7. The gyroscope according to claim 3,

a) further including a substantially rigid substrate;

and,

b) wherein said primary optical waveguide and said sensing system are mounted on said substantially rigid substrate.

8. The gyroscope according to claim 7, wherein said substrate includes silicon.

9. The gyroscope according to claim 7, wherein said substrate includes silica glass and sapphire.

10. The gyroscope according to claim 7, wherein said substrate includes lithium niobium and lithium tantalite.

11. The gyroscope according to claim 7, wherein said optical source and said detector are mounted on said substrate.

12. The gyroscope according to claim 11, wherein said optical source includes a broadband low coherence length light source.

13. The gyroscope according to claim 12, wherein said broadband low coherence length light source includes an edge light emitting diode.

14. The gyroscope according to claim 12, wherein said broadband low coherence length light source is a superluminescent diode.

15. The gyroscope according to claim 1, wherein said primary optical waveguide is substantially a spiral.

16. The gyroscope according to claim 1, wherein said primary optical waveguide, said first optical waveguide, and said second optical waveguide are doped with phosphorus and germanium.

17. The gyroscope according to claim 1, wherein said primary optical waveguide, said first optical waveguide, and said second optical waveguide are doped with silicon nitride.

18. An optically actuated gyroscope comprising:

a) a closed optical path adapted to communicate a first and a second light wave through a single path in opposing directions; and

,

b) a sensing system having,

1) a first waveguide and a second waveguide, said first waveguide having a light transmittal period differing from said second waveguide, said first waveguide adapted to receive light emitting from a first end of said closed optical path, said second waveguide adapted to receive light emitting from a second end of said closed optical path, and,

2) a beam combiner adapted to combine light emitting from a second end of said first waveguide and said second waveguide.

19. The optically actuated gyroscope according to claim 18, wherein said first waveguide of said sensing system is longer than said second waveguide of said sensing system.

20. The optically actuated gyroscope according to claim 19,

a) further including an optical source producing light at a predefined wavelength, said light being communicated to the first end and the second end of said closed optical path; and,

b) wherein said first waveguide of said sensing system is one quarter wavelength longer than said second waveguide of said sensing system.

21. The optically actuated gyroscope according to claim 18, wherein a portion of said first waveguide of said sensing system is treated to increase light transmittal time therein.

22. The optically actuated gyroscope according to claim 20, wherein said optical source includes a broadband low coherence length light source.

23. The optically actuated gyroscope according to claim 18, wherein said closed optical path is substantially a spiral.