Resonant Loop Patents (Class 356/461)
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Publication number: 20150098088Abstract: A resonator fiber optic gyroscope is provided. The resonator fiber optic gyroscope includes a gyroscope resonator, a laser; a clockwise modulator; a clockwise circulator; a clockwise reflection detector; a first-lock-in-amplifier, a clockwise-resonance-tracking servo to receive output from the first-lock-in-amplifier and to provide feedback to the laser to lock the laser to the gyroscope resonator; a clockwise transmission detector to detect an optical beam output from the counter-clockwise input port; a second servo; a second-lock-in-amplifier; and a third-lock-in-amplifier. The first and second lock-in-amplifiers demodulate at the first harmonic of the modulation frequency. The second-lock-in-amplifier demodulates at the second harmonic of the modulation frequency. Either the modulation frequency of the clockwise optical beam is locked to (n+0.5) times the FSR through the second servo, where n is zero or a positive integer, or the FSR is locked to 1/(n+0.Type: ApplicationFiled: October 7, 2013Publication date: April 9, 2015Applicant: Honeywell International Inc.Inventors: Tiequn Qiu, Jianfeng Wu, Lee K. Strandjord, Glen A. Sanders
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Patent number: 9001336Abstract: A resonator fiber optic gyroscope is provided. The resonator fiber optic gyroscope includes a gyroscope resonator, a laser; a clockwise modulator; a clockwise circulator; a clockwise reflection detector; a first-lock-in-amplifier, a clockwise-resonance-tracking servo to receive output from the first-lock-in-amplifier and to provide feedback to the laser to lock the laser to the gyroscope resonator; a clockwise transmission detector to detect an optical beam output from the counter-clockwise input port; a second servo; a second-lock-in-amplifier; and a third-lock-in-amplifier. The first and second lock-in-amplifiers demodulate at the first harmonic of the modulation frequency. The second-lock-in-amplifier demodulates at the second harmonic of the modulation frequency. Either the modulation frequency of the clockwise optical beam is locked to (n+0.5) times the FSR through the second servo, where n is zero or a positive integer, or the FSR is locked to 1/(n+0.Type: GrantFiled: October 7, 2013Date of Patent: April 7, 2015Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Jianfeng Wu, Lee K. Strandjord, Glen A. Sanders
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Publication number: 20150070707Abstract: One embodiment is directed towards a stabilized laser including a laser to produce light at a frequency and a resonator coupled to the laser such that the light from the laser circulates therethrough. The laser also includes Pound-Drever-Hall (PDH) feedback electronics configured to adjust the frequency of the light from the laser to reduce phase noise in response to light sensed at the reflection port of the resonator and transmission port feedback electronics configured to adjust the frequency of the light from the laser toward resonance of the resonator at the transmission port in response to the light sensed at the transmission port of the resonator, wherein the transmission port feedback electronics adjust the frequency at a rate at least ten times slower than the PDH feedback electronics.Type: ApplicationFiled: November 18, 2014Publication date: March 12, 2015Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
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Patent number: 8976364Abstract: A microfabricated optical gyroscope that utilizes a linear array of micron scale optical ring resonators closely spaced to allow evanescent coupling of electromagnetic fields in adjacent resonators. Within each resonator, the optical Sagnac effect produces a phase difference between clockwise and counterclockwise propagating light that is proportional to the inertial rotation rate perpendicular to the plane of the resonator. The disclosure enhances the overall sensitivity to rotations by varying the strengths of the evanescent coupling between resonators and/or the circumferences of the resonators. The size and coupling strengths control the optical interference between resonators.Type: GrantFiled: October 4, 2012Date of Patent: March 10, 2015Assignee: The Trustees of The Stevens Institute of TechnologyInventors: Christopher Sorrentino, John Robert Emmet Toland, Christopher Search, Rainer Martini
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Patent number: 8947671Abstract: A resonator fiber optic gyroscope (RFOG) is provided.Type: GrantFiled: February 22, 2013Date of Patent: February 3, 2015Assignee: Honeywell International Inc.Inventors: Lee K. Strandjord, Mary K. Salit, Tiequn Qiu, Glen A. Sanders
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Publication number: 20150015892Abstract: One embodiment is directed towards a resonator fiber optic gyroscope (RFOG) including a resonator, one or more light sources coupled to the resonator, and resonance tracking electronics coupled to the resonator. The one or more light sources are configured to produce at least two light beams for input into the fiber coil, the at least two light beams including a first light beam at a first frequency and a second light beam at a second frequency, the first and second frequencies locked to nearby resonance modes of the resonator. The resonance tracking electronics are configured to process output light from the resonator and generate a signal therefrom, the signal indicative of a rotation rate of the resonator. The fiber coil has approximately zero total accumulated chromatic dispersion at the first frequency and the second frequency of the first light beam and the second light beam.Type: ApplicationFiled: July 9, 2013Publication date: January 15, 2015Inventors: Tiequn Qiu, Glen A. Sanders, Lee K. Strandjord
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Patent number: 8913246Abstract: An all-fiber interferometric fiber optic gyroscope having a minimum reciprocal configuration is described. The gyroscope comprises a polarized light source, a light detector, a light source coupler, a fiber optic loop coupler, and a polarization maintaining fiber optic loop. A first port of the light source coupler is counter-axially coupled to an output end of the polarized light source, and a second port of the light source coupler on the same side as the first port is coupled to the light detector. A third port on the other side of the light source coupler is counter-axially coupled to the fiber optic loop coupler, and the fiber optic loop coupler is counter-axially coupled to the polarization maintaining fiber optic loop. The light source splits the input polarized light and polarizes the optical signal propagated along a transmission arm alone, where the first and third ports are on the same transmission arm.Type: GrantFiled: August 9, 2013Date of Patent: December 16, 2014Assignee: Peking UniversityInventors: Xinyue Wang, Ziyu Wang
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Patent number: 8908187Abstract: An exemplary resonator fiber optic gyroscope comprises a resonator having an optical fiber loop; a light source configured to generate a light beam; and an intensity modulation circuit coupled between the light source and the resonator. The intensity modulation circuit is configured to modulate the intensity of the light beam from the light source to output an intensity modulated signal to the resonator. The intensity modulation circuit is configured to produce the intensity modulated signal such that harmonics of the intensity modulated signal which overlap a primary wave of a counter-propagating light beam in the resonator have an amplitude below a predetermined threshold. Amplitudes below the predetermined threshold are negligible.Type: GrantFiled: November 2, 2011Date of Patent: December 9, 2014Assignee: Honeywell International Inc.Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
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Patent number: 8873063Abstract: A low-noise resonator fiber-optic gyroscope is provided. The low-noise resonator fiber-optic gyroscope includes at least one laser to output a reference optical beam, a first-optical-beam frequency controller to modulate the first optical beam at a first-modulation frequency, a second-optical-beam frequency controller to modulate the second optical beam at a second-modulation frequency to form a second-frequency-modulated optical beam, a fiber resonator having a counter-clockwise-input end configured to input the first-frequency-modulated optical beam and the clockwise-input end configured to input the second-frequency-modulated optical beam; a first-frequency demodulator to demodulate an optical beam output from the clockwise-input end of the fiber resonator; and a second-frequency demodulator to demodulate an optical beam output from the counter-clockwise-input end of the fiber resonator.Type: GrantFiled: August 14, 2012Date of Patent: October 28, 2014Assignee: Honeywell International Inc.Inventors: Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu, Tiequn Qiu
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Patent number: 8830479Abstract: In one embodiment a system including a resonator fiber-optic gyroscope configured to measure rotation rate is provided. The resonator fiber-optic gyroscope includes a sensing resonator have a first resonance frequency for a first laser beam propagation direction and a second resonance frequency for a second laser beam propagation direction, an optical mixer coupled to an output of the sensing resonator and configured to mix an output of the sensing resonator with a reference laser, wherein the optical mixer outputs a beat signal, and a resonance tracking electronics coupled to the optical mixer. The resonance tracking electronics are configured to demodulate the beat signal at a frequency offset to produce first in-phase and quadrature demodulated information, generate R-squared information from a sum of squares of the first in-phase and quadrature demodulated information, and demodulate the R-squared information at a resonance tracking modulation frequency.Type: GrantFiled: January 28, 2013Date of Patent: September 9, 2014Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Lee K. Strandjord, Glen A. Sanders, Mary K. Salit
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Patent number: 8830478Abstract: Systems and methods for measuring rotation using an optical frequency comb stimulated Brillouin scattering gyroscope are provided. In certain embodiments, a system comprises a light source that produces a multiple-frequency light beam based on an optical frequency comb; and an optical fiber resonator coupled to the light source, the multiple-frequency light beam propagating in a first direction within the optical fiber resonator, wherein the multiple -frequency light beam generates stimulated Brillouin scattering (SBS) for a frequency, wherein the Brillouin scattering generates an SBS light beam to propagate in a second direction, the first direction being opposite in direction to the second direction. The system also comprises a servo to control the frequencies of the optical frequency comb to lock a plurality of component frequencies on resonance peaks of the optical fiber resonator; and a mixer that determines a frequency difference between the SBS light beam and the multiple-frequency light beam.Type: GrantFiled: December 4, 2012Date of Patent: September 9, 2014Assignee: Honeywell International Inc.Inventors: Jianfeng Wu, Tiequn Qiu, Glen A. Sanders, Lee K. Strandjord
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Publication number: 20140240712Abstract: A resonator fiber optic gyroscope (RFOG) is provided.Type: ApplicationFiled: February 22, 2013Publication date: August 28, 2014Applicant: HONEYWELL INTERNATIONAL INC.Inventor: HONEYWELL INTERNATIONAL INC.
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Publication number: 20140211211Abstract: In one embodiment a system including a resonator fiber-optic gyroscope configured to measure rotation rate is provided. The resonator fiber-optic gyroscope includes a sensing resonator have a first resonance frequency for a first laser beam propagation direction and a second resonance frequency for a second laser beam propagation direction, an optical mixer coupled to an output of the sensing resonator and configured to mix an output of the sensing resonator with a reference laser, wherein the optical mixer outputs a beat signal, and a resonance tracking electronics coupled to the optical mixer. The resonance tracking electronics are configured to demodulate the beat signal at a frequency offset to produce first in-phase and quadrature demodulated information, generate R-squared information from a sum of squares of the first in-phase and quadrature demodulated information, and demodulate the R-squared information at a resonance tracking modulation frequency.Type: ApplicationFiled: January 28, 2013Publication date: July 31, 2014Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Tiequn Qiu, Lee K. Strandjord, Glen A. Sanders, Mary K. Salit
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Publication number: 20140204387Abstract: An optical-fiber filter system to narrow a linewidth and to reduce noise fluctuations of an optical beam is provided. The optical-fiber filter system includes an optical fiber having a first end-face and an opposing second end-face, the first end-face and the second end-face setting a fiber length; a fiber Bragg grating having a first reflectivity positioned at the first end-face; and a reflector having a second reflectivity positioned at the second end-face. When the optical beam at a first frequency is coupled from a laser into one of the first end-face or the second end-face, a resonant cavity is established at the first frequency between the fiber Bragg grating and the reflector while Brillouin scattered light shifted from the first frequency within the optical fiber is transmitted through the fiber Bragg grating.Type: ApplicationFiled: July 10, 2012Publication date: July 24, 2014Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Chellappan Narayanan, Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu
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Publication number: 20140152994Abstract: Systems and methods for measuring rotation using an optical frequency comb stimulated Brillouin scattering gyroscope are provided. In certain embodiments, a system comprises a light source that produces a multiple-frequency light beam based on an optical frequency comb; and an optical fiber resonator coupled to the light source, the multiple-frequency light beam propagating in a first direction within the optical fiber resonator, wherein the multiple-frequency light beam generates stimulated Brillouin scattering (SBS) for a frequency, wherein the Brillouin scattering generates an SBS light beam to propagate in a second direction, the first direction being opposite in direction to the second direction. The system also comprises a servo to control the frequencies of the optical frequency comb to lock a plurality of component frequencies on resonance peaks of the optical fiber resonator; and a mixer that determines a frequency difference between the SBS light beam and the multiple-frequency light beam.Type: ApplicationFiled: December 4, 2012Publication date: June 5, 2014Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Jianfeng Wu, Tiequn Qiu, Glen A. Sanders, Lee K. Strandjord
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Patent number: 8736845Abstract: A laser stabilization system includes laser source having first and second ends; first waveguide portion having first and second ends, first end of first waveguide portion coupled to first end of laser source; second waveguide portion having first and second ends, first end of second waveguide portion coupled to second end of laser source; micro-cavity coupled between second end of first waveguide portion and second end of second waveguide portion, micro-cavity having resonant frequency; and electronic locking loop coupled between micro-cavity and laser source, wherein electronic locking loop electronically locks laser source to resonant frequency of micro-cavity; wherein first waveguide portion is optical locking loop coupled between micro-cavity and laser source, wherein optical locking loop optically locks laser source to resonant frequency of micro-cavity; micro-cavity stabilization loop coupled with micro-cavity, wherein micro-cavity stabilization loop stabilizes resonant frequency of micro-cavity to refType: GrantFiled: April 27, 2012Date of Patent: May 27, 2014Assignee: Honeywell International Inc.Inventors: Jianfeng Wu, Jennifer S. Strabley, Tiequn Qiu, Glen A. Sanders
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Patent number: 8705044Abstract: A method for detecting rotation includes providing a plurality of resonant waveguides generally adjacent to one another and optically coupled to one another. Each resonant waveguide of the plurality of resonant waveguides is configured to allow light to propagate along the resonant waveguide in a planar path. The method further includes propagating light along each path in a clockwise direction or along each path in a counterclockwise direction.Type: GrantFiled: September 20, 2011Date of Patent: April 22, 2014Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Matthew A. Terrel, Michel J. F. Digonnet, Shanhui Fan
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Patent number: 8659760Abstract: A resonator fiber optic gyroscope comprises a first light source having a first frequency comb spectrum, and a second light source having a second frequency comb spectrum. A first filter is in optical communication with the first light source and configured to pass a first frequency comb portion. A second filter is in optical communication with the second light source and configured to pass a second frequency comb portion. A resonator is in optical communication with the first and second filters. The free spectral range values of the first and second frequency comb portions are adjusted to be an odd integer multiple of the free spectral range value of the resonances of the resonator. The second frequency comb portion is spectrally separated apart from the first frequency comb portion by a multiple of the free spectral range value of the resonances plus a frequency value proportional to rotation rate.Type: GrantFiled: April 12, 2012Date of Patent: February 25, 2014Assignee: Honeywell International Inc.Inventors: Glen A. Sanders, Lee K. Strandjord, Tiequn Qiu
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Publication number: 20140049780Abstract: A low-noise resonator fiber-optic gyroscope is provided. The low-noise resonator fiber-optic gyroscope includes at least one laser to output a reference optical beam, a first-optical-beam frequency controller to modulate the first optical beam at a first-modulation frequency, a second-optical-beam frequency controller to modulate the second optical beam at a second-modulation frequency to form a second-frequency-modulated optical beam, a fiber resonator having a counter-clockwise-input end configured to input the first-frequency-modulated optical beam and the clockwise-input end configured to input the second-frequency-modulated optical beam; a first-frequency demodulator to demodulate an optical beam output from the clockwise-input end of the fiber resonator; and a second-frequency demodulator to demodulate an optical beam output from the counter-clockwise-input end of the fiber resonator.Type: ApplicationFiled: August 14, 2012Publication date: February 20, 2014Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu, Tiequn Qiu
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Patent number: 8619262Abstract: A laser gyro includes an amplifying solid element and a device for vibrating said amplifying solid element at a predetermined frequency, along an axis of revolution of said amplifying solid element. The geometry of said amplifying solid element is such that a natural mode of mechanical vibration of said amplifying solid element corresponds to said predetermined frequency.Type: GrantFiled: October 26, 2009Date of Patent: December 31, 2013Assignee: ThalesInventors: Andre Boura, François Gutty, Francois Perez
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Publication number: 20130271770Abstract: A resonator fiber optic gyroscope comprises a first light source having a first frequency comb spectrum, and a second light source having a second frequency comb spectrum. A first filter is in optical communication with the first light source and configured to pass a first frequency comb portion. A second filter is in optical communication with the second light source and configured to pass a second frequency comb portion. A resonator is in optical communication with the first and second filters. The free spectral range values of the first and second frequency comb portions are adjusted to be an odd integer multiple of the free spectral range value of the resonances of the resonator. The second frequency comb portion is spectrally separated apart from the first frequency comb portion by a multiple of the free spectral range value of the resonances plus a frequency value proportional to rotation rate.Type: ApplicationFiled: April 12, 2012Publication date: October 17, 2013Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Glen A. Sanders, Lee K. Strandjord, Tiequn Qiu
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Patent number: 8514401Abstract: An all-fiber interferometric fiber optic gyroscope having a minimum reciprocal configuration is described. The gyroscope comprises a light source, a light detector, a light source coupler, a fiber optic loop coupler, and a polarization maintaining fiber optic loop. A first port of the light source coupler is coupled, with polarization axis alignment, to an output end of the light source, and a second port of the light source coupler on the same side as the first port is coupled to the light detector. A third port on the other side of the light source coupler is coupled, with polarization axis alignment, to the fiber optic loop coupler, and the fiber optic loop coupler is coupled, with polarization axis alignment, to the polarization maintaining fiber optic loop. The light source splits the input light and polarizes the optical signal propagated along a transmission arm alone, where the first and third ports are on the same transmission arm.Type: GrantFiled: March 7, 2011Date of Patent: August 20, 2013Assignee: Peking UniversityInventors: Xinyue Wang, Ziyu Wang
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Patent number: 8446589Abstract: Systems and methods for reducing intensity modulation-induced rotation rate measurement error in a resonator optical gyroscope. The method includes tapping an intensity modulated light beam, directing a portion of the tapped light beam toward a photo detector, outputting from the photo detector a signal proportional to the amplitude variation of the light beam, amplifying the signal, and then providing the signal to the intensity modulator as a control input. Intensity modulation-induced error is reduced by an amount proportional to the gain of the feedback loop.Type: GrantFiled: October 19, 2009Date of Patent: May 21, 2013Assignee: Honeywell International Inc.Inventors: Lee Strandjord, Glen A. Sanders, Tiequn Qiu
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Patent number: 8446590Abstract: An optical-fiber filter is provided. The optical-fiber filter includes an optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The first end-face and the second end-face are coated with reflective coatings. When an optical beam emitted from a laser is coupled into one of the first end-face or the second end-face, an optical beam output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.Type: GrantFiled: June 1, 2011Date of Patent: May 21, 2013Assignee: Honeywell International Inc.Inventors: Glen A. Sanders, John Feth, Lee K. Strandjord, Tiequn Qiu
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Publication number: 20130107271Abstract: An exemplary resonator fiber optic gyroscope comprises a resonator having an optical fiber loop; a light source configured to generate a light beam; and an intensity modulation circuit coupled between the light source and the resonator. The intensity modulation circuit is configured to modulate the intensity of the light beam from the light source to output an intensity modulated signal to the resonator. The intensity modulation circuit is configured to produce the intensity modulated signal such that harmonics of the intensity modulated signal which overlap a primary wave of a counter-propagating light beam in the resonator have an amplitude below a predetermined threshold. Amplitudes below the predetermined threshold are negligible.Type: ApplicationFiled: November 2, 2011Publication date: May 2, 2013Applicant: Honeywell International Inc.Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
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Patent number: 8422021Abstract: A method for inhibiting zero drift of an all-fiber interferometric fiber optic gyroscope and a corresponding all-fiber interferometric fiber optic gyroscope are disclosed. The method comprises: reversing the polarity of an AC voltage applied to a PZT piezoelectric ceramic phase modulator according to a predetermined half-cycle time period, and making half of the difference between output rotation rates of the gyroscope in two adjacent half-cycle time periods as the output rotation rate of the gyroscope in a cycle. A phase reversal switch and a DSP chip are added to the all-fiber interferometric fiber optic gyroscope. The phase reversal switch is used for controlling the polarity of the AC voltage, and the DSP chip is used for outputting a square wave signal to control the phase reversal switch and for calculating the output rotation rate of the gyroscope according to the output signal of a demodulation/amplifier circuit.Type: GrantFiled: March 7, 2011Date of Patent: April 16, 2013Assignee: Peking UniversityInventors: Xinyue Wang, Changhong He, Ziyu Wang
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Publication number: 20130070252Abstract: Systems and methods for a hollow core resonant filter are provided. In one embodiment, a hollow-core fiber resonant cavity comprises: a hollow-core fiber having a first and second ends; a first and a second pigtail fiber each of solid core fiber material. A tip of the first pigtail is optically aligned with the first-end to couple light from the first pigtail to the hollow core fiber across a first free-space gap. A tip of the second pigtail is optically aligned with the second-end to couple light from the second pigtail to the hollow-core fiber across a second free-space gap. The tip of the second pigtail is coated to reflect light received from the second-end back across the second free-space gap into the second-end. The tip of the first pigtail is coated to reflect light received from the first-end back across the first free-space gap into the first-end.Type: ApplicationFiled: September 21, 2011Publication date: March 21, 2013Applicant: HONEYWELL INTERNATIONAL INC.Inventor: John Feth
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Publication number: 20120307253Abstract: An optical-fiber filter is provided. The optical-fiber filter includes an optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The first end-face and the second end-face are coated with reflective coatings. When an optical beam emitted from a laser is coupled into one of the first end-face or the second end-face, an optical beam output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.Type: ApplicationFiled: June 1, 2011Publication date: December 6, 2012Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Glen A. Sanders, John Feth, Lee K. Strandjord, Tiequn Qiu
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Publication number: 20120239329Abstract: A Sagnac phase shift tracking method of fiber-optic gyroscopes comprises determining, for both a current time and a previous time, a value of a primary harmonic demodulated signal and a value of a secondary harmonic demodulated signal from a detector output in the fiber-optic gyroscope; and determining the Sagnac phase shift of the fiber-optic gyroscope for the current time based on the values of the primary harmonic demodulated signal and the secondary harmonic demodulated signal for both the current time and the previous time.Type: ApplicationFiled: August 25, 2011Publication date: September 20, 2012Applicant: University, PekingInventors: Chuanchuan Yang, Ziyu Wang
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Patent number: 8259301Abstract: Systems and methods for reducing rotation sensing errors in a resonator fiber optic gyroscope. An example method propagates a primary light wave through a resonator having an optical fiber and a plurality of optical surfaces for directing the light wave exiting a first end of the optical fiber back into an opposite end of the optical fiber. The optical fiber is wound onto a piezo-electric transducer (PZT) tube. A sinusoidal voltage is applied to the PZT tube to modulate a length of a fiber cavity within the optical fiber. The amplitude and frequency of the fiber cavity length modulation is selected to produce a relative phase modulation between the primary light wave and a double-back reflected light wave, such that the rotation sensing errors resulting from double backscatter of light is at a frequency above a frequency band of interest. This allows the associated error to be filtered out of the rotation rate signal.Type: GrantFiled: September 23, 2009Date of Patent: September 4, 2012Assignee: Honeywell International Inc.Inventors: Lee Strandjord, Glen A. Sanders, Tiequn Qiu
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Publication number: 20120218555Abstract: An optical ingredient-measuring apparatus is provided for measuring a concentration of an optically rotative substance. The apparatus includes a sensor main body which detects a phase difference between linear polarized light beams that propagate through an optical fiber loop in opposite directions, a circular polarized input component interposed in the middle of the optical fiber loop having first and second converters that convert the linear polarized light propagating through the optical fiber loop into left-hand and right-hand circular polarized light, and a concentration detector, installed in the sensor main body, which calculates the concentration of the substance in the sample based on the detected phase difference.Type: ApplicationFiled: February 1, 2012Publication date: August 30, 2012Applicant: HITACHI CABLE, LTD.Inventors: Tatsuya KUMAGAI, Shinji KOMATSUZAKI
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Patent number: 8237932Abstract: A fiber optic gyroscope includes first and second gyroscopes. The first gyroscope includes: a first light source for emitting two lights; a first optical fiber loop which includes a sensor coil structured such that an optical fiber is wound in a multilayer manner, through which the two lights travel in opposite directions, and which constitutes a laser resonant circuit with the first light source; and a first optical detector for detecting an angular velocity based on a beat frequency which is produced by the two lights. The second gyroscope includes: a second light source for emitting light; an optical distributor for dividing the light into two lights; a second optical fiber loop through which the two lights travel in opposite directions and enter both respective ends of the sensor coil; and a second optical detector for detecting an angular velocity based on a phase difference between the two lights.Type: GrantFiled: July 28, 2009Date of Patent: August 7, 2012Assignee: Minebea Co., Ltd.Inventor: Atsushi Kitamura
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Patent number: 8223341Abstract: A resonator fiber optic gyroscope includes a sensing resonator having a first resonance frequency for a first laser beam propagation direction and a second resonance frequency for a second laser beam propagation direction; an intensity modulator coupled to an output of the sensing resonator and configured to modulate the intensity of a signal output from the sensing resonator, wherein the intensity modulator modulates the output signal at an intensity modulation frequency; and resonance tracking electronics coupled to an output of the intensity modulator and configured to demodulate the intensity modulated signal output from the intensity modulator at a resonance tracking modulation frequency to produce a first demodulated signal; the resonance tracking electronics further configured to demodulate the first demodulated signal at the intensity modulation frequency, wherein the intensity modulation frequency is different from the resonance tracking modulation frequency.Type: GrantFiled: May 28, 2010Date of Patent: July 17, 2012Assignee: Honeywell International Inc.Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
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Patent number: 8213019Abstract: A RFOG comprises a reference laser configured to produce a reference laser beam; a first laser source configured to produce a first laser beam; a second laser source configured to produce a second laser beam; a sensing resonator coupled to the first and second laser sources such that the first and second laser beams propagate through the sensing resonator in first and second directions, respectively; resonance tracking electronics configured to generate first and second control signals that indicate when the first and second laser beams, respectively, are off resonance; first and second optical combiners configured to beat the first and second outputs of the sensing resonator with the reference laser beam creating first and second beat signals, respectively; wherein the resonance tracking electronics is configured to discriminate between at least one rotation-sensing error and the first and second outputs of the resonator based on the first and second beat signals.Type: GrantFiled: September 7, 2010Date of Patent: July 3, 2012Assignee: Honeywell International Inc.Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
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Publication number: 20120092676Abstract: A method for inhibiting zero drift of an all-fiber interferometric fiber optic gyroscope and a corresponding all-fiber interferometric fiber optic gyroscope are disclosed. The method comprises: reversing the polarity of an AC voltage applied to a PZT piezoelectric ceramic phase modulator according to a predetermined half-cycle time period, and making half of the difference between output rotation rates of the gyroscope in two adjacent half-cycle time periods as the output rotation rate of the gyroscope in a cycle. A phase reversal switch and a DSP chip are added to the all-fiber interferometric fiber optic gyroscope. The phase reversal switch is used for controlling the polarity of the AC voltage, and the DSP chip is used for outputting a square wave signal to control the phase reversal switch and for calculating the output rotation rate of the gyroscope according to the output signal of a demodulation/amplifier circuit.Type: ApplicationFiled: March 7, 2011Publication date: April 19, 2012Applicant: Peking UniversityInventors: Xinyue Wang, Changhong He, Ziyu Wang
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Publication number: 20120057167Abstract: A RFOG comprises a reference laser configured to produce a reference laser beam; a first laser source configured to produce a first laser beam; a second laser source configured to produce a second laser beam; a sensing resonator coupled to the first and second laser sources such that the first and second laser beams propagate through the sensing resonator in first and second directions, respectively; resonance tracking electronics configured to generate first and second control signals that indicate when the first and second laser beams, respectively, are off resonance; first and second optical combiners configured to beat the first and second outputs of the sensing resonator with the reference laser beam creating first and second beat signals, respectively; wherein the resonance tracking electronics is configured to discriminate between at least one rotation-sensing error and the first and second outputs of the resonator based on the first and second beat signals.Type: ApplicationFiled: September 7, 2010Publication date: March 8, 2012Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
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Publication number: 20120050745Abstract: A resonator fiber optic gyroscope (RFOG) is disclosed that reduces rotation rate error instability. In one embodiment, the RFOG comprises a resonator optical ring cavity, a first light source in optical communication with the ring cavity and configured to generate a clockwise optical signal, and a second light source in optical communication with the ring cavity and configured to generate a counter-clockwise optical signal. The RFOG also includes a first optical component in optical communication with the first light source and the ring cavity. The first optical component is configured to prevent the clockwise optical signal from being back-reflected to the first light source. A second optical component is in optical communication with the second light source and the ring cavity. The second optical component is configured to prevent the counter-clockwise optical signal from being back-reflected to the second light source.Type: ApplicationFiled: August 30, 2010Publication date: March 1, 2012Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Tiequn Qiu, Lee K. Strandjord, Glen A. Sanders
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Patent number: 8098380Abstract: Multiple resonator fiber optic gyroscope (RFOG) configurations comprising one or more mode filters inside the resonator are adopted to effectively suppress unwanted high order spatial modes which can be a significant source of gyro bias errors. The resonator comprises at least a loop fiber, either two or more in/out coupling elements, and connectors that link elements into a circulating loop. Directional elements may be used to separate output light from input light in some of the embodiments. In all embodiments, mode filters are placed in the resonator to guarantee that the light reaching the photodetector is filtered by at least one mode filter in the resonator at least once. The mode filters may contain both spatial mode filters (such as single mode fibers or waveguides) and polarization mode filters (such as polarizing elements) so that both spatial and polarization mode filtering can be implemented simultaneously.Type: GrantFiled: July 21, 2009Date of Patent: January 17, 2012Assignee: Honeywell International Inc.Inventors: Glen A. Sanders, Tiequn Qiu, Lee Strandjord
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Resonator optical gyroscope having input beam modulation optimized for high sensitivity and low bias
Patent number: 8085407Abstract: Systems and methods for optimizing input beam modulation for high gyro sensitivity and low bias errors. The present invention is a resonator optical gyroscope having an optimized phase-modulation amplitude (frequency) for a selected modulation frequency (amplitude) that maximizes the gyro signal-to-noise (S/N) sensitivity. For selected values of the phase modulation amplitude, the polarization cross-coupling induced intensity modulation can be nulled. By setting the phase modulation amplitudes substantially close to these nulling points (e.g. M=3.832 or 7.016 radians, which causes the first order Bessel function to be zero J1(M)=0) and then optimizing the modulation frequency, the intensity modulation induced bias is reduced to zero and gyro S/N sensitivity is maximized.Type: GrantFiled: August 12, 2009Date of Patent: December 27, 2011Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Glen A. Sanders, Lee Strandjord -
Publication number: 20110292396Abstract: A resonator fiber optic gyroscope includes a sensing resonator having a first resonance frequency for a first laser beam propagation direction and a second resonance frequency for a second laser beam propagation direction; an intensity modulator coupled to an output of the sensing resonator and configured to modulate the intensity of a signal output from the sensing resonator, wherein the intensity modulator modulates the output signal at an intensity modulation frequency; and resonance tracking electronics coupled to an output of the intensity modulator and configured to demodulate the intensity modulated signal output from the intensity modulator at a resonance tracking modulation frequency to produce a first demodulated signal; the resonance tracking electronics further configured to demodulate the first demodulated signal at the intensity modulation frequency, wherein the intensity modulation frequency is different from the resonance tracking modulation frequency.Type: ApplicationFiled: May 28, 2010Publication date: December 1, 2011Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
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Patent number: 8068233Abstract: Substantially symmetric RFOG configurations for rotation rate sensing using two input/output coupling components. Configurations are disclosed where optical coupling components handles both input and output lightwaves. Reducing the number of input/output coupling components while maintaining a substantially symmetric configuration for the CW and CCW beam reduces losses, prevents realization of bias errors due to asymmetric light paths in the resonator, and produces better signal to noise performance. In addition, the invention discloses systems integrating multiple functions into compact micro-optic devices that are easier to fabricate and package, leading to compact RFOGs with reduced cost and improved manufacturability.Type: GrantFiled: May 14, 2009Date of Patent: November 29, 2011Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Lee Strandjord, Glen A. Sanders
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Patent number: 8068232Abstract: An optical waveguide gyroscope includes at least one optical coupler configured to receive a first optical signal at a first port, to transmit a second optical signal to a second port, and to transmit a third optical signal to a third port. The optical waveguide gyroscope further includes a plurality of resonant waveguides optically coupled to the second port and the third port. The resonant waveguides are generally adjacent to one another and optically coupled to one another. At least a portion of the second optical signal propagates from the second port to the third port by propagating through the plurality of resonant waveguides, and at least a portion of the third optical signal propagates from the third port to the second port by propagating through the plurality of resonant waveguides.Type: GrantFiled: April 1, 2009Date of Patent: November 29, 2011Assignee: The Board of Trustees of the Leland Stanford Junior UniversityInventors: Matthew A. Terrel, Michel J. F. Digonnet, Shanhui Fan
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Publication number: 20110255094Abstract: Optical gyroscope devices based on optical whispering gallery mode resonators that measure rotations based on rotation-induced optical phase shift in optical whispering gallery mode resonators.Type: ApplicationFiled: March 23, 2011Publication date: October 20, 2011Applicant: OEwaves, Inc.Inventors: Makan Mohageg, Lute Maleki, David Seidel, Vladimir S. Ilchenko, Andrey B. Matsko, Anatoliy A. Savchenkov, Wei Liang
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Patent number: 8031343Abstract: A waveguide optical gyroscope is disclosed. The waveguide optical gyroscope includes a laser, two detectors, a set of couplers and a set of waveguides. The laser generates a light beam. A first waveguide guides the light beam to travel in a first direction, and a second waveguide guides the light beam to travel in a second direction. The first and second waveguides are coupled to several ring waveguides via the couplers. The first detector detects the arrival of the light beam traveling from the first waveguide, and the second detector detects the arrival of the light beam traveling from the second waveguide.Type: GrantFiled: August 29, 2008Date of Patent: October 4, 2011Assignee: BAE Systems Information and Electronic Systems Integration Inc.Inventors: Daniel N. Carothers, Jefferson E. Odhner
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Patent number: 8009296Abstract: A resonator gyroscope comprises a reference laser generator to produce a reference light; a first slave light source to produce a first slave light locked to the reference light; a second slave light source to produce a second slave light locked to the reference light; a first optical filter cavity coupled to at least one of the first and second slave light sources to filter out high-frequency fluctuations in the respective first and second slave lights; a resonator coupled to said first and second light sources, the resonator having first and second counter-propagating directions and resonance tracking electronics coupled to the resonator to generate a first beat frequency, a second beat frequency, and a third beat frequency; wherein the rotational rate of the resonator gyroscope is a function of the first, second and third beat frequencies.Type: GrantFiled: December 22, 2009Date of Patent: August 30, 2011Assignee: Honeywell International Inc.Inventors: Glen A. Sanders, Tiequn Qiu, Lee K. Strandjord
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Publication number: 20110205546Abstract: A laser gyro includes an amplifying solid element and a device for vibrating said amplifying solid element at a predetermined frequency, along an axis of revolution of said amplifying solid element. The geometry of said amplifying solid element is such that a natural mode of mechanical vibration of said amplifying solid element corresponds to said predetermined frequency.Type: ApplicationFiled: October 26, 2009Publication date: August 25, 2011Applicant: THALESInventors: Andre Boura, François Gutty, François Perez
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Publication number: 20110141477Abstract: A resonator gyroscope comprises a reference laser generator to produce a reference light; a first slave light source to produce a first slave light locked to the reference light; a second slave light source to produce a second slave light locked to the reference light; a first optical filter cavity coupled to at least one of the first and second slave light sources to filter out high-frequency fluctuations in the respective first and second slave lights; a resonator coupled to said first and second light sources, the resonator having first and second counter-propagating directions and resonance tracking electronics coupled to the resonator to generate a first beat frequency, a second beat frequency, and a third beat frequency; wherein the rotational rate of the resonator gyroscope is a function of the first, second and third beat frequencies.Type: ApplicationFiled: December 22, 2009Publication date: June 16, 2011Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Glen A. Sanders, Tiequn Qiu, Lee K. Strandjord
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Patent number: 7933020Abstract: A resonator gyroscope comprises a reference laser generator to produce a reference light; a first slave light source to produce a first slave light locked to the reference light; a second slave light source to produce a second slave light locked to the reference light; a resonator coupled to said first and second light sources, the resonator having first and second counter-propagating directions and resonance tracking electronics coupled to the Sagnac resonator to generate a first beat frequency based on a first resonance frequency for the first counter-propagating direction, a second beat frequency based on a second resonance frequency for the second counter-propagating direction, and a third beat frequency based on a third resonance frequency for the second counter-propagating direction; wherein the rotational rate of the resonator gyroscope is a function of the first, second and third beat frequencies.Type: GrantFiled: December 13, 2009Date of Patent: April 26, 2011Assignee: Honeywell International Inc.Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
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RESONATOR OPTICAL GYROSCOPE HAVING INPUT BEAM MODULATION OPTIMIZED FOR HIGH SENSITIVITY AND LOW BIAS
Publication number: 20110037985Abstract: Systems and methods for optimizing input beam modulation for high gyro sensitivity and low bias errors. The present invention is a resonator optical gyroscope having an optimized phase-modulation amplitude (frequency) for a selected modulation frequency (amplitude) that maximizes the gyro signal-to-noise (S/N) sensitivity. For selected values of the phase modulation amplitude, the polarization cross-coupling induced intensity modulation can be nulled. By setting the phase modulation amplitudes substantially close to these nulling points (e.g. M=3.832 or 7.016 radians, which causes the first order Bessel function to be zero J1(M)=0) and then optimizing the modulation frequency, the intensity modulation induced bias is reduced to zero and gyro S/N sensitivity is maximized.Type: ApplicationFiled: August 12, 2009Publication date: February 17, 2011Applicant: Honeywell International Inc.Inventors: Tiequn Qiu, Glen A. Sanders, Lee Strandjord -
Patent number: 7889350Abstract: Hollow core fiber RFOG having symmetric M-(or W-)shape, three-(or two-)mirror configurations. These symmetric configurations help to cancel out polarization error induced bias of the RFOG even when light of the unwanted ESOP is present. The RFOG resonator with optical components forming substantially small cross-coupling angles between their polarization axes, and/or with polarizing elements inserted into the resonator, and/or with resonator mirrors having identical reflectivity for light of different polarization states, can effectively reduce the polarization mode induced bias error.Type: GrantFiled: November 25, 2008Date of Patent: February 15, 2011Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Glen A Sanders, Lee Strandjord