US4408882A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical gyroscope with time dependent wavelength
Assignee: United States Department of the Navy
•
Filing: 1981-07-02
•
Granted: 1983-10-11
•
Expires: 2001-07-02
Abstract
Abstract A Sagnac rotation sensing interferometer disposed on a rotating platform use as a gyroscope comprising a wound optical fiber light path, a beam splitter for splitting a light beam into two beams directed to traverse the optical path in opposite directions, a light source circuit for generating a light beam which is switched between two wavelengths at a switching or modulation frequency substantially higher than the speed of change of the phase due to rotation, and a detector for extracting a signal from the recombined beam interference pattern at the wavelength modulation frequency, this signal being proportional to the phase shift caused by rotation.
Inventors
- 👤 Sang K. Sheem
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:31
CPC Classifications
G; G01; G01C; G01C19/00; G01C19/58; G01C19/64; G01C19/72
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
184 words
A Sagnac rotation measurement device comprising: means for generating a plurality of different beams of electromagnetic energy with each beam having a different wavelength; a light path circuit including a plurality of turns of optical path in or parallel to a given plane; means for splitting a beam into two beams and for directing one of said two beams to travel in a clockwise direction around said light path circuit and directing the other of said two beams to travel in a counter-clockwise direction around said light path circuit, and for recombining said two beams after having traversed through their respective directions in said light path circuit to produce electromagnetic wave interference; means for alternately gating each of said plurality of different wavelength beams from said generating means to said splitting means at a frequency substantially higher than the rates of change of phase due to rotation in the plane of said light path circuit and due to system noises; and means for extracting a signal at said wavelength gating frequency from said interference pattern in order to detect a rotation-caused phase change therefrom.
Claim 2
Dependent Claim
184 words
A Sagnac rotation measurement device comprising: means for generating a plurality of different beams of electromagnetic energy with each beam having a different wavelength; a light path circuit including a plurality of turns of optical path in or parallel to a given plane; means for splitting a beam into two beams and for directing one of said two beams to travel in a clockwise direction around said light path circuit and directing the other of said two beams to travel in a counter-clockwise direction around said light path circuit, and for recombining said two beams after having traversed through their respective directions in said light path circuit to produce electromagnetic wave interference; means for alternately gating each of said plurality of different wavelength beams from said generating means to said splitting means at a frequency substantially higher than the rates of change of phase due to rotation in the plane of said light path circuit and due to system noises; and means for extracting a signal at said wavelength gating frequency from said interference pattern in order to detect a rotation-caused phase change therefrom.
Claim 3
Dependent Claim
22 words
A rotation measurement device as defined in claim 1, wherein said beam generating means includes means for generating two separate wavelength beams.
Claim 4
Dependent Claim
37 words
A rotation measurement device as defined in claim 2, wherein said beam generating means comprises means for generating light at a given frequency and its second harmonic to yield two of beams each having a different wavelength.
Claim 5
Dependent Claim
29 words
A rotation measurement device as defined in claim 2, wherein said light path circuit comprises a wound length of optical fiber with each end terminating at said splitting means.
Claim 6
Dependent Claim
22 words
A rotation measurement device as defined in claim 4, wherein said optical fiber is wound in the shape of a cylindrical helix.
Claim 7
Dependent Claim
44 words
A rotation measurement device as defined in claim 5, wherein said extracting means comprises: a spectrum analyzer; and sensing means for sensing the light from the wave interference at said splitting means and generating a signal proportional thereto for application to said spectrum analyzer.
Claim 8
Dependent Claim
44 words
A rotation measurement device as defined in claim 5, wherein said extracting means comprises: a locking amplifier; and sensing means for sensing the light from the wave interference at said splitting means and generating a signal proportional thereto for application to said locking amplifier.
Claim 9
Dependent Claim
27 words
A rotation measurement device as defined in claim 1, wherein said generating means comprises a plurality of laser light sources for generating light beams with different wavelengths.
Claim 10
Dependent Claim
66 words
A rotation rate measurement device comprising: a conventional Sagnac interferometer disposed on a platform for generating Sagnac optical interference; means for generating and applying an optical beam having a time modulated wavelength to said Sagnac interferometer; and means for extracting a signal from said interferometer interference pattern at the time modulation rate of said optical beam wavelength in order to detect a rotation-caused phase change therefrom.
Claim 11
Dependent Claim
66 words
A rotation rate measurement device comprising: a conventional Sagnac interferometer disposed on a platform for generating Sagnac optical interference; means for generating and applying an optical beam having a time modulated wavelength to said Sagnac interferometer; and means for extracting a signal from said interferometer interference pattern at the time modulation rate of said optical beam wavelength in order to detect a rotation-caused phase change therefrom.
Claim 12
Dependent Claim
52 words
A rotation rate measurement device as defined in claim 9, wherein said beam generating means comprises: means for generating two separate wavelength beams; and gating means for alternately gating each of said beams to said Sagnac interferometer at a frequency substantially higher than the rate of change of phase due to rotation.
Claim 13
Dependent Claim
63 words
A rotation measurement device as defined in claim 9, wherein said beam generating means comprises: means for generating light at a given frequency and one harmonic thereof to yield two beams having different wavelengths; and gating means for alternately gating each of said beams to said Sagnac interferometer at a frequency substantially higher than the rate of change of phase due to rotation.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-10 | 1987-04-11 | 1987-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-10 | 1991-04-11 | 1991-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-10 | 1995-04-11 | 1995-10-11 | $7700.00 | Window Closed / Lapsed |