Resonant Loop Patents (Class 356/461)
  • Publication number: 20150098088
    Abstract: 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: Application
    Filed: October 7, 2013
    Publication date: April 9, 2015
    Applicant: Honeywell International Inc.
    Inventors: Tiequn Qiu, Jianfeng Wu, Lee K. Strandjord, Glen A. Sanders
  • Patent number: 9001336
    Abstract: 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: Grant
    Filed: October 7, 2013
    Date of Patent: April 7, 2015
    Assignee: Honeywell International Inc.
    Inventors: Tiequn Qiu, Jianfeng Wu, Lee K. Strandjord, Glen A. Sanders
  • Publication number: 20150070707
    Abstract: 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: Application
    Filed: November 18, 2014
    Publication date: March 12, 2015
    Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
  • Patent number: 8976364
    Abstract: 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: Grant
    Filed: October 4, 2012
    Date of Patent: March 10, 2015
    Assignee: The Trustees of The Stevens Institute of Technology
    Inventors: Christopher Sorrentino, John Robert Emmet Toland, Christopher Search, Rainer Martini
  • Patent number: 8947671
    Abstract: A resonator fiber optic gyroscope (RFOG) is provided.
    Type: Grant
    Filed: February 22, 2013
    Date of Patent: February 3, 2015
    Assignee: Honeywell International Inc.
    Inventors: Lee K. Strandjord, Mary K. Salit, Tiequn Qiu, Glen A. Sanders
  • Publication number: 20150015892
    Abstract: 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: Application
    Filed: July 9, 2013
    Publication date: January 15, 2015
    Inventors: Tiequn Qiu, Glen A. Sanders, Lee K. Strandjord
  • Patent number: 8913246
    Abstract: 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: Grant
    Filed: August 9, 2013
    Date of Patent: December 16, 2014
    Assignee: Peking University
    Inventors: Xinyue Wang, Ziyu Wang
  • Patent number: 8908187
    Abstract: 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: Grant
    Filed: November 2, 2011
    Date of Patent: December 9, 2014
    Assignee: Honeywell International Inc.
    Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
  • Patent number: 8873063
    Abstract: 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: Grant
    Filed: August 14, 2012
    Date of Patent: October 28, 2014
    Assignee: Honeywell International Inc.
    Inventors: Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu, Tiequn Qiu
  • Patent number: 8830479
    Abstract: 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: Grant
    Filed: January 28, 2013
    Date of Patent: September 9, 2014
    Assignee: Honeywell International Inc.
    Inventors: Tiequn Qiu, Lee K. Strandjord, Glen A. Sanders, Mary K. Salit
  • Patent number: 8830478
    Abstract: 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: Grant
    Filed: December 4, 2012
    Date of Patent: September 9, 2014
    Assignee: Honeywell International Inc.
    Inventors: Jianfeng Wu, Tiequn Qiu, Glen A. Sanders, Lee K. Strandjord
  • Publication number: 20140240712
    Abstract: A resonator fiber optic gyroscope (RFOG) is provided.
    Type: Application
    Filed: February 22, 2013
    Publication date: August 28, 2014
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventor: HONEYWELL INTERNATIONAL INC.
  • Publication number: 20140211211
    Abstract: 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: Application
    Filed: January 28, 2013
    Publication date: July 31, 2014
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Tiequn Qiu, Lee K. Strandjord, Glen A. Sanders, Mary K. Salit
  • Publication number: 20140204387
    Abstract: 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: Application
    Filed: July 10, 2012
    Publication date: July 24, 2014
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Chellappan Narayanan, Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu
  • Publication number: 20140152994
    Abstract: 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: Application
    Filed: December 4, 2012
    Publication date: June 5, 2014
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Jianfeng Wu, Tiequn Qiu, Glen A. Sanders, Lee K. Strandjord
  • Patent number: 8736845
    Abstract: 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 ref
    Type: Grant
    Filed: April 27, 2012
    Date of Patent: May 27, 2014
    Assignee: Honeywell International Inc.
    Inventors: Jianfeng Wu, Jennifer S. Strabley, Tiequn Qiu, Glen A. Sanders
  • Patent number: 8705044
    Abstract: 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: Grant
    Filed: September 20, 2011
    Date of Patent: April 22, 2014
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Matthew A. Terrel, Michel J. F. Digonnet, Shanhui Fan
  • Patent number: 8659760
    Abstract: 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: Grant
    Filed: April 12, 2012
    Date of Patent: February 25, 2014
    Assignee: Honeywell International Inc.
    Inventors: Glen A. Sanders, Lee K. Strandjord, Tiequn Qiu
  • Publication number: 20140049780
    Abstract: 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: Application
    Filed: August 14, 2012
    Publication date: February 20, 2014
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Glen A. Sanders, Lee K. Strandjord, Jianfeng Wu, Tiequn Qiu
  • Patent number: 8619262
    Abstract: 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: Grant
    Filed: October 26, 2009
    Date of Patent: December 31, 2013
    Assignee: Thales
    Inventors: Andre Boura, François Gutty, Francois Perez
  • Publication number: 20130271770
    Abstract: 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: Application
    Filed: April 12, 2012
    Publication date: October 17, 2013
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Glen A. Sanders, Lee K. Strandjord, Tiequn Qiu
  • Patent number: 8514401
    Abstract: 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: Grant
    Filed: March 7, 2011
    Date of Patent: August 20, 2013
    Assignee: Peking University
    Inventors: Xinyue Wang, Ziyu Wang
  • Patent number: 8446589
    Abstract: 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: Grant
    Filed: October 19, 2009
    Date of Patent: May 21, 2013
    Assignee: Honeywell International Inc.
    Inventors: Lee Strandjord, Glen A. Sanders, Tiequn Qiu
  • Patent number: 8446590
    Abstract: 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: Grant
    Filed: June 1, 2011
    Date of Patent: May 21, 2013
    Assignee: Honeywell International Inc.
    Inventors: Glen A. Sanders, John Feth, Lee K. Strandjord, Tiequn Qiu
  • Publication number: 20130107271
    Abstract: 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: Application
    Filed: November 2, 2011
    Publication date: May 2, 2013
    Applicant: Honeywell International Inc.
    Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
  • Patent number: 8422021
    Abstract: 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: Grant
    Filed: March 7, 2011
    Date of Patent: April 16, 2013
    Assignee: Peking University
    Inventors: Xinyue Wang, Changhong He, Ziyu Wang
  • Publication number: 20130070252
    Abstract: 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: Application
    Filed: September 21, 2011
    Publication date: March 21, 2013
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventor: John Feth
  • Publication number: 20120307253
    Abstract: 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: Application
    Filed: June 1, 2011
    Publication date: December 6, 2012
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Glen A. Sanders, John Feth, Lee K. Strandjord, Tiequn Qiu
  • Publication number: 20120239329
    Abstract: 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: Application
    Filed: August 25, 2011
    Publication date: September 20, 2012
    Applicant: University, Peking
    Inventors: Chuanchuan Yang, Ziyu Wang
  • Patent number: 8259301
    Abstract: 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: Grant
    Filed: September 23, 2009
    Date of Patent: September 4, 2012
    Assignee: Honeywell International Inc.
    Inventors: Lee Strandjord, Glen A. Sanders, Tiequn Qiu
  • Publication number: 20120218555
    Abstract: 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: Application
    Filed: February 1, 2012
    Publication date: August 30, 2012
    Applicant: HITACHI CABLE, LTD.
    Inventors: Tatsuya KUMAGAI, Shinji KOMATSUZAKI
  • Patent number: 8237932
    Abstract: 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: Grant
    Filed: July 28, 2009
    Date of Patent: August 7, 2012
    Assignee: Minebea Co., Ltd.
    Inventor: Atsushi Kitamura
  • Patent number: 8223341
    Abstract: 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: Grant
    Filed: May 28, 2010
    Date of Patent: July 17, 2012
    Assignee: Honeywell International Inc.
    Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
  • Patent number: 8213019
    Abstract: 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: Grant
    Filed: September 7, 2010
    Date of Patent: July 3, 2012
    Assignee: Honeywell International Inc.
    Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
  • Publication number: 20120092676
    Abstract: 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: Application
    Filed: March 7, 2011
    Publication date: April 19, 2012
    Applicant: Peking University
    Inventors: Xinyue Wang, Changhong He, Ziyu Wang
  • Publication number: 20120057167
    Abstract: 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: Application
    Filed: September 7, 2010
    Publication date: March 8, 2012
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
  • Publication number: 20120050745
    Abstract: 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: Application
    Filed: August 30, 2010
    Publication date: March 1, 2012
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Tiequn Qiu, Lee K. Strandjord, Glen A. Sanders
  • Patent number: 8098380
    Abstract: 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: Grant
    Filed: July 21, 2009
    Date of Patent: January 17, 2012
    Assignee: Honeywell International Inc.
    Inventors: Glen A. Sanders, Tiequn Qiu, Lee Strandjord
  • Patent number: 8085407
    Abstract: 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: Grant
    Filed: August 12, 2009
    Date of Patent: December 27, 2011
    Assignee: Honeywell International Inc.
    Inventors: Tiequn Qiu, Glen A. Sanders, Lee Strandjord
  • Publication number: 20110292396
    Abstract: 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: Application
    Filed: May 28, 2010
    Publication date: December 1, 2011
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Lee K. Strandjord, Glen A. Sanders, Tiequn Qiu
  • Patent number: 8068233
    Abstract: 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: Grant
    Filed: May 14, 2009
    Date of Patent: November 29, 2011
    Assignee: Honeywell International Inc.
    Inventors: Tiequn Qiu, Lee Strandjord, Glen A. Sanders
  • Patent number: 8068232
    Abstract: 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: Grant
    Filed: April 1, 2009
    Date of Patent: November 29, 2011
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Matthew A. Terrel, Michel J. F. Digonnet, Shanhui Fan
  • Publication number: 20110255094
    Abstract: 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: Application
    Filed: March 23, 2011
    Publication date: October 20, 2011
    Applicant: OEwaves, Inc.
    Inventors: Makan Mohageg, Lute Maleki, David Seidel, Vladimir S. Ilchenko, Andrey B. Matsko, Anatoliy A. Savchenkov, Wei Liang
  • Patent number: 8031343
    Abstract: 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: Grant
    Filed: August 29, 2008
    Date of Patent: October 4, 2011
    Assignee: BAE Systems Information and Electronic Systems Integration Inc.
    Inventors: Daniel N. Carothers, Jefferson E. Odhner
  • Patent number: 8009296
    Abstract: 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: Grant
    Filed: December 22, 2009
    Date of Patent: August 30, 2011
    Assignee: Honeywell International Inc.
    Inventors: Glen A. Sanders, Tiequn Qiu, Lee K. Strandjord
  • Publication number: 20110205546
    Abstract: 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: Application
    Filed: October 26, 2009
    Publication date: August 25, 2011
    Applicant: THALES
    Inventors: Andre Boura, François Gutty, François Perez
  • Publication number: 20110141477
    Abstract: 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: Application
    Filed: December 22, 2009
    Publication date: June 16, 2011
    Applicant: HONEYWELL INTERNATIONAL INC.
    Inventors: Glen A. Sanders, Tiequn Qiu, Lee K. Strandjord
  • Patent number: 7933020
    Abstract: 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: Grant
    Filed: December 13, 2009
    Date of Patent: April 26, 2011
    Assignee: Honeywell International Inc.
    Inventors: Lee K. Strandjord, Tiequn Qiu, Glen A. Sanders
  • Publication number: 20110037985
    Abstract: 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: Application
    Filed: August 12, 2009
    Publication date: February 17, 2011
    Applicant: Honeywell International Inc.
    Inventors: Tiequn Qiu, Glen A. Sanders, Lee Strandjord
  • Patent number: 7889350
    Abstract: 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: Grant
    Filed: November 25, 2008
    Date of Patent: February 15, 2011
    Assignee: Honeywell International Inc.
    Inventors: Tiequn Qiu, Glen A Sanders, Lee Strandjord