US3807866A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ring laser gyroscope having a constant output beat-frequency
Assignee: Boeing North American Inc
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Filing: 1972-04-21
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Granted: 1974-04-30
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Expires: 1992-04-21
Abstract
Abstract A ring laser gyroscope having counter-rotating beams rotating around a closed path. A laser gain section is provided for generating the counter-rotating beams. A means for generating and applying a magnetic field to a Faraday substance which substance is located within the optical path of the counter-rotating beams provides a selected bias to the optical beams. Means for combining and detecting a portion of the counter-rotating beams outside of the closed path yields a first signal which contains inertial rotation rate and Faraday bias information. Means for detecting selected components of the laser beams outside of the closed path yields a second signal that contains Faraday bias information but does not contain rotation rate information. A servo means responsive to the first electrical signal generates a control signal which signal is applied to the means for generating a magnetic field to create an operating condition that is held constant to thereby eliminate scale factor nonlinearities and stray field errors in the detected gyroscope rates. A means for correcting the frequency of the first signal by an amount determined by the frequency of the second signal is provided to yield a rotation rate devoid of Faraday bias or scale factor nonlinearity errors.
Inventors
- 👤 W Zingery
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:23
CPC Classifications
G; G01; G01C; G01C19/00; G01C19/58; G01C19/64; G01C19/66; G01C19/667; G02; G02F; G02F2/00; G02F2/002; H; H01; H01S; H01S3/00; H01S3/05; H01S3/08; H01S3/081; H01S3/083
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
212 words
A ring laser gyroscope comprising in combination: means for generating two counter-rotating beams of circularly polarized light about a closed optical path each of said beams having a first component polarized in a first sense and a second component polarized in a second sense different from said first sense; a Faraday substance positioned in said closed optical path; means for generating a magnetic field in said Faraday substance; first means for sampling said counter-rotating beams and selecting a like polarized component from each of said beams; means for heterodyning the selected components of said counterrotating beams together; means for transforming the heterodyned beams into a first proportional electrical signal; servo means for receiving said first proportional electrical signal and providing a control signal to said means for generating a magnetic field so as to control the strength of said magnetic field to maintain said proportional electrical signal at a constant value; second means for sampling one of said counter-rotating beams; means for transforming the first and second components of the sampled beam from said second means into a second proportional electrical signal; and means for obtaining a difference signal between said first and said second proportional electrical signals which difference signal is proportional to the rate of rotation of said laser gyroscope.
Claim 2
Dependent Claim
212 words
A ring laser gyroscope comprising in combination: means for generating two counter-rotating beams of circularly polarized light about a closed optical path each of said beams having a first component polarized in a first sense and a second component polarized in a second sense different from said first sense; a Faraday substance positioned in said closed optical path; means for generating a magnetic field in said Faraday substance; first means for sampling said counter-rotating beams and selecting a like polarized component from each of said beams; means for heterodyning the selected components of said counterrotating beams together; means for transforming the heterodyned beams into a first proportional electrical signal; servo means for receiving said first proportional electrical signal and providing a control signal to said means for generating a magnetic field so as to control the strength of said magnetic field to maintain said proportional electrical signal at a constant value; second means for sampling one of said counter-rotating beams; means for transforming the first and second components of the sampled beam from said second means into a second proportional electrical signal; and means for obtaining a difference signal between said first and said second proportional electrical signals which difference signal is proportional to the rate of rotation of said laser gyroscope.
Claim 3
Dependent Claim
68 words
The ring laser gyroscope according to claim 1 wherein said means for transforming the sampled beam from said second means is comprised of: a polarizer positioned in the path of said sampled beam so as to transform said circularly polarized beam into a linear polarized beam; and a photodetector positioned to receive the linear polarized beam and to connect the linear polarized beam into a proportional electrical signal.
Claim 4
Dependent Claim
121 words
A ring laser gyroscope comprising: means for generating two circularly polarized counter-rotating beams of light about a closed loop optical path each of said beams having a first component polarized in a first sense and a second component polarized in a second sense different from said first sense; means positioned in said optical path for applying a bias to said counter-rotating beams; means for sampling said two counter-rotating beams and selecting a like polarized components from each of said beams and combining the selected components into a heterodyned beam having a beat frequency; and servo means responsive to said heterodyned beam for controlling the applied bias so as to maintain the beat frequency of said heterodyned beam at a constant value.
Claim 5
Dependent Claim
121 words
A ring laser gyroscope comprising: means for generating two circularly polarized counter-rotating beams of light about a closed loop optical path each of said beams having a first component polarized in a first sense and a second component polarized in a second sense different from said first sense; means positioned in said optical path for applying a bias to said counter-rotating beams; means for sampling said two counter-rotating beams and selecting a like polarized components from each of said beams and combining the selected components into a heterodyned beam having a beat frequency; and servo means responsive to said heterodyned beam for controlling the applied bias so as to maintain the beat frequency of said heterodyned beam at a constant value.
Claim 6
Dependent Claim
125 words
The ring laser gyroscope according to claim 3 wherein said means for sampling said two counter-rotating beams is comprised of: a partially transparent reflector positioned in said closed loop optical path to allow the clockwise beam and the counterclockwise beam to transverse different paths external to the closed loop optical path; means for optically combining the two counter-rotating beams external of said closed loop optical path; a half-wave plate interposed in the path of one of the beams passed by said partially transparent reflector; a quarter-wave plate positioned in the path of said optically combined beams; a polarizer positioned in the path of the beam from said quarter wave plate; and photodetector means for transferring the beam passed by said polarizer into an electrical signal.
Claim 7
Dependent Claim
73 words
The ring laser gyroscope according to claim 3 wherein said means positioned in said optical path for applying a bias is comprised of: a Faraday rotational element; magnetic means for creating a magnetic field in said Faraday element which magnetic field is parallel to the axis of the counter-rotating optical beams passing thru the Faraday element; and wherein said servo means controls the magnitude of the magnetic field generated by said magnetic means.
Claim 8
Dependent Claim
156 words
A ring laser gyroscope comprising: means for generating two circularly polarized counter-rotating beams of light about a closed loop optical path each of said beams having a first component polarized in a first sense and a second component polarized in a second sense different from said first sense; means positioned in said optical path for applying a bias to said counter-rotating beams; means for sampling said two counter-rotating beams and selecting a like polarized component from each of said beams and combining the selected components into a heterodyned beam having a beat frequency; means for sampling one of said two counter-rotating beams; servo means responsive to said one sampled beam for controlling the applied bias so as to maintain said one sampled beam at a constant value; and means responsive to said beam having a beat-frequency and said one sampled beam to provide a signal proportional to the rate of rotation of said ring laser gyroscope.
Claim 9
Dependent Claim
156 words
A ring laser gyroscope comprising: means for generating two circularly polarized counter-rotating beams of light about a closed loop optical path each of said beams having a first component polarized in a first sense and a second component polarized in a second sense different from said first sense; means positioned in said optical path for applying a bias to said counter-rotating beams; means for sampling said two counter-rotating beams and selecting a like polarized component from each of said beams and combining the selected components into a heterodyned beam having a beat frequency; means for sampling one of said two counter-rotating beams; servo means responsive to said one sampled beam for controlling the applied bias so as to maintain said one sampled beam at a constant value; and means responsive to said beam having a beat-frequency and said one sampled beam to provide a signal proportional to the rate of rotation of said ring laser gyroscope.
Claim 10
Dependent Claim
123 words
The ring laser gyroscope according to claim 6 wherein said means for sampling said two counter-rotating is comprised of: a partially transparent reflector positioned in said closed loop optical path to allow the clockwise beam and The counterclockwise beam to transverse different paths external to the closed loop optical path; means for optically combining the two counter-rotating beams external of said closed loop optical path; a half-wave plate interposed in the path of one of the beams passed by said partially transparent reflector; a quarter-wave plate positioned in the path of said optically combined beams; a polarizer positioned in the path of the beam from said quarter-wave plate; and photodetector means for transferring the beam passed by said polarizer into an electrical signal.
Claim 11
Dependent Claim
73 words
The ring laser gyroscope according to claim 6 wherein said means positioned in said optical path for applying a bias is comprised of: a Faraday rotational element; magnetic means for creating a magnetic field in said Faraday element which magnetic field is parallel to the axis of the counter-rotating optical beams passing thru the Faraday element; and wherein said servo means controls the magnitude of the magnetic field generated by said magnetic means.
References Cited (Backward Citations)
US3642375A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-29 | 1977-10-29 | 1978-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-29 | 1981-10-29 | 1982-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-29 | 1985-10-29 | 1986-04-30 | $7700.00 | Window Closed / Lapsed |