US4123162A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multioscillator ring laser gyro output information processing system
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1977-02-09
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Granted: 1978-10-31
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Expires: 1997-02-09
Abstract
Abstract A four mode ring laser gyro has its four modes at different frequencies combined and applied to a single photo diode. The output from the photo diode is applied to a non-linear device, and the resultant sum and difference frequencies are applied to (1) a laser cavity length control circuit, (2) a rotation rate detection circuit, and (3) a rotation direction determination circuit. The cavity length control circuit operates by the determination of 100% modulation of one of the beat frequencies by a second one. The direction determination circuit utilizes the phase of an AC dithering power supply which varies the anode to cathode plasma current of the laser gyro.
Inventors
- 👤 Virgil E. Sanders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:44
CPC Classifications
G; G01; G01C; G01C19/00; G01C19/58; G01C19/64; G01C19/66; G01C19/667
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
100 words
A ring laser gyro comprising: a multi-oscillator ring laser including means for generating four modes of laser oscillation at four respectively different frequencies, and with two of the modes propagating in each direction; an optical detector for receiving all of said four modes; means coupled to said detector for determining the rate of rotation of said ring laser; means coupled to said detector for determining the direction of rotation of said ring laser; and servo means coupled to said detector for adjusting the length of the cavity of said ring laser to substantially equalize the intensity of said four modes.
Claim 2
Dependent Claim
100 words
A ring laser gyro comprising: a multi-oscillator ring laser including means for generating four modes of laser oscillation at four respectively different frequencies, and with two of the modes propagating in each direction; an optical detector for receiving all of said four modes; means coupled to said detector for determining the rate of rotation of said ring laser; means coupled to said detector for determining the direction of rotation of said ring laser; and servo means coupled to said detector for adjusting the length of the cavity of said ring laser to substantially equalize the intensity of said four modes.
Claim 3
Dependent Claim
17 words
A ring laser gyro as defined in claim 1 wherein said detector is a single photo diode.
Claim 4
Dependent Claim
25 words
A ring laser gyro as defined in claim 1 wherein said direction determining means includes means for varying the plasma current of said ring laser.
Claim 5
Dependent Claim
43 words
A ring laser gyro as defined in claim 3, further comprising means for comparing the phase of a beat signal derived from said four modes with the phase of said plasma varying means to determine the direction of rotation of said laser gyro.
Claim 6
Dependent Claim
42 words
A ring laser gyro as defined in claim 1 further comprising means for fixing said cavity length to a length corresponding to 100% modulation of one beat signal of said four oscillation modes, by another beat signal of said four oscillation modes.
Claim 7
Dependent Claim
143 words
A ring laser gyro comprising: a multi-oscillator ring laser including means for generating four modes of laser oscillation at four respectively different frequencies, and with two of the modes propagating in each direction; means including an optical detector for receiving all of said four modes and mixing them to produce sum and difference frequencies; means including a low pass filter for providing first and second gyro signals which have substantially linear frequency versus rate of rotation characteristics, but which are of opposite slope; means coupled to receive said two gyro signals for determining the rate of rotation of said ring laser; means coupled to said detector for determining the direction of rotation of said ring laser; and servo means coupled to said detector for adjusting the length of the cavity of said ring laser to substantially equalize the intensity of said four modes.
Claim 8
Dependent Claim
143 words
A ring laser gyro comprising: a multi-oscillator ring laser including means for generating four modes of laser oscillation at four respectively different frequencies, and with two of the modes propagating in each direction; means including an optical detector for receiving all of said four modes and mixing them to produce sum and difference frequencies; means including a low pass filter for providing first and second gyro signals which have substantially linear frequency versus rate of rotation characteristics, but which are of opposite slope; means coupled to receive said two gyro signals for determining the rate of rotation of said ring laser; means coupled to said detector for determining the direction of rotation of said ring laser; and servo means coupled to said detector for adjusting the length of the cavity of said ring laser to substantially equalize the intensity of said four modes.
Claim 9
Dependent Claim
17 words
A ring laser gyro as defined in claim 6 wherein said detector is a single photo diode.
Claim 10
Dependent Claim
25 words
A ring laser gyro as defined in claim 6 wherein said direction determining means includes means for varying the plasma current of said ring laser.
Claim 11
Dependent Claim
44 words
A ring laser gyro as defined in claim 8, further comprising means for comparing the phase of a beat signal derived from said two gyro signals with the phase of said plasma varying means to determine the direction of rotation of said laser gyro.
Claim 12
Dependent Claim
37 words
A ring laser gyro as defined in claim 6 further comprising means for fixing said cavity length to a length corresponding to 100% modulation of one of said gyro signals by the other of said gyro signals.
References Cited (Backward Citations)
US3937578A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-30 | 1982-05-01 | 1982-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-30 | 1986-05-01 | 1986-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-30 | 1990-05-01 | 1990-10-31 | $7700.00 | Window Closed / Lapsed |