Patents by Inventor Tiequn Qiu
Tiequn Qiu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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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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Patent number: 7894073Abstract: Apparatus for providing Bias-Instability reduction in Fiber Optic Gyroscopes are provided. In one embodiment, an optical circuit for a fiber optic gyroscope having a broadband light source and an optical fiber loop comprises: a PM fiber of length v; an IOC coupled to the PM fiber via a pigtail of length d1, a second pigtail with length of d2, and a third pigtail with length of d3; a splitter that splits light received from the first pigtail into a first and second beams directed to the second and third pigtails; and a depolarizer circuit coupled to said fiber loop including a first fiber section of length x, a second fiber section of length z, a third fiber section of length w and a fourth fiber section of length y; and wherein the lengths of v, x, y, d1 and d3 are proportioned to avoid regions of high bias instability.Type: GrantFiled: August 2, 2010Date of Patent: February 22, 2011Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Steven J. Sanders, Sorin Mosor, 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
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Publication number: 20110019198Abstract: 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: ApplicationFiled: July 21, 2009Publication date: January 27, 2011Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Glen A. Sanders, Tiequn Qiu, Lee Strandjord
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Publication number: 20100316332Abstract: Apparatus for providing Bias-Instability reduction in Fiber Optic Gyroscopes are provided. In one embodiment, an optical circuit for a fiber optic gyroscope having a broadband light source and an optical fiber loop comprises: a PM fiber of length v; an IOC coupled to the PM fiber via a pigtail of length d1, a second pigtail with length of d2, and a third pigtail with length of d3; a splitter that splits light received from the first pigtail into a first and second beams directed to the second and third pigtails; and a depolarizer circuit coupled to said fiber loop including a first fiber section of length x, a second fiber section of length z, a third fiber section of length w and a fourth fiber section of length y; and wherein the lengths of v, x, y, d1 and d3 are proportioned to avoid regions of high bias instability.Type: ApplicationFiled: August 2, 2010Publication date: December 16, 2010Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Tiequn Qiu, Steven J. Sanders, Sorin Mosor, Glen A. Sanders
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Publication number: 20100290057Abstract: 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: ApplicationFiled: May 14, 2009Publication date: November 18, 2010Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Tiequn Qiu, Lee Strandjord, Glen A. Sanders
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Publication number: 20100284018Abstract: Effective relative intensity noise (RIN) subtraction systems and methods for improving ARW performance of a depolarized gyros. This invention taps the RIN detector light in the sensing loop, after the light transmits through the depolarizer and the coil but before it combines with the counter propagating lightwave. The tapped RIN lightwaves are polarized with pass-axis orientated in the same direction as that of the IOC, so that the RIN detector receives lightwaves with spectrum substantially identical to that of the rate detector, leading to more effective RIN subtraction.Type: ApplicationFiled: May 11, 2009Publication date: November 11, 2010Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Tiequn Qiu, Steven J. Sanders, Chellappan Narayanan
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Publication number: 20100225923Abstract: 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: ApplicationFiled: October 19, 2009Publication date: September 9, 2010Applicant: Honeywell International Inc.Inventors: Lee Strandjord, Glen A. Sanders, Tiequn Qiu
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Publication number: 20100225922Abstract: 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: ApplicationFiled: September 23, 2009Publication date: September 9, 2010Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Lee Strandjord, Glen A. Sanders, Tiequn Qiu
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Patent number: 7777889Abstract: A computer-implementable method of reducing bias instability in a fiber optic gyroscope includes receiving, with a computer, a first data set enabling the computer to generate a model of the gyroscope, including a light source, a photodetector, and a plurality of optical components and fiber sections coupling the light source to the photodetector, and a light signal to be propagated from the light source to the photodetector. The light signal has an associated wavelength spectrum. For each wavelength of the spectrum, the relative lightwave intensity reaching the photodetector is calculated. A signal-wave intensity and a spurious-wave intensity are determined from the calculated relative lightwave intensities. A scale factor is determined from the signal-wave intensity. The spurious-wave intensity is integrated over the wavelength spectrum of the light source to obtain a total spurious-wave intensity. A rate bias error is determined based on the total spurious-wave intensity and the scale factor.Type: GrantFiled: August 7, 2008Date of Patent: August 17, 2010Assignee: Honeywell International Inc.Inventors: Tiequn Qiu, Steven J. Sanders, Sorin Mosor, Glen A. Sanders
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Publication number: 20100128277Abstract: 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: ApplicationFiled: November 25, 2008Publication date: May 27, 2010Applicant: Honeywell International Inc.Inventors: Tiequn Qiu, Glen A. Sanders, Lee Strandjord
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Publication number: 20100073681Abstract: A fiber optic gyroscope includes a light source, a coupler coupled to the light source, a photodetector coupled to the coupler, an integrated optic circuit (IOC) coupled to the coupler by a first element, and a sensing loop coupled to the IOC by second and third elements. At least one of the first, second and third elements includes a polarizing element.Type: ApplicationFiled: September 24, 2008Publication date: March 25, 2010Applicant: Honeywell International, Inc.Inventors: Tiequn Qiu, Steven J. Sanders, Sorin Moser
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Publication number: 20100033729Abstract: A computer-implementable method of reducing bias instability in a fiber optic gyroscope includes receiving, with a computer, a first data set enabling the computer to generate a model of the gyroscope, including a light source, a photodetector, and a plurality of optical components and fiber sections coupling the light source to the photodetector, and a light signal to be propagated from the light source to the photodetector. The light signal has an associated wavelength spectrum. For each wavelength of the spectrum, the relative lightwave intensity reaching the photodetector is calculated. A signal-wave intensity and a spurious-wave intensity are determined from the calculated relative lightwave intensities. A scale factor is determined from the signal-wave intensity. The spurious-wave intensity is integrated over the wavelength spectrum of the light source to obtain a total spurious-wave intensity. A rate bias error is determined based on the total spurious-wave intensity and the scale factor.Type: ApplicationFiled: August 7, 2008Publication date: February 11, 2010Applicant: HONEYWELL INTERNATIONAL INC.Inventors: Tiequn Qiu, Steven J. Sanders, Sorin Mosor, Glen A. Sanders
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Patent number: 7522284Abstract: Methods and apparatus are provided for attenuating rotation rate errors in a resonator gyro. The gyro includes a ring resonator having a hollow core optical fiber coil and optical elements that are selected and/or oriented to reduce stray light that may be present in input light beams introduced to the ring resonator. The resonator has a predetermined mode. One of the optical elements partially transmits a portion of the input light beam to a first end of the fiber coil while partially transmitting a portion of the input light beam to a filter. Light having the predetermined mode is accepted into the first end of the fiber coil, and the filter accepts light of the input light beam having a corresponding mode. Transmission components of the circulating light beams indicates resonance peaks of the counter-propagating directions of the ring resonator.Type: GrantFiled: September 29, 2006Date of Patent: April 21, 2009Assignee: Honeywell International Inc.Inventors: Glen A. Sanders, Lee K. Strandjord, Tiequn Qiu
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Publication number: 20080079947Abstract: Methods and apparatus are provided for attenuating rotation rate errors in a resonator gyro. The gyro includes a ring resonator having a hollow core optical fiber coil and optical elements that are selected and/or oriented to reduce stray light that may be present in input light beams introduced to the ring resonator. The resonator has a predetermined mode. One of the optical elements partially transmits a portion of the input light beam to a first end of the fiber coil while partially transmitting a portion of the input light beam to a filter. Light having the predetermined mode is accepted into the first end of the fiber coil, and the filter accepts light of the input light beam having a corresponding mode. Transmission components of the circulating light beams indicates resonance peaks of the counter-propagating directions of the ring resonator.Type: ApplicationFiled: September 29, 2006Publication date: April 3, 2008Inventors: Glen A. Sanders, Lee K. Strandjord, Tiequn Qiu