Patent application number | Description | Published |
20080231485 | SYSTEMS AND METHODS FOR IMPROVING DATA CONVERTERS - Systems and methods for improving efficiency of a data converter. An example method generates a noise signal, alters the spectrum of the noise signal based on operation of an associated data converter, and supplies the altered spectrum noise signal to the associated data converter. The data converter is a digital-to-analog converter or an analog-to-digital converter. The altered spectrum noise signal is notched at frequencies of interest. The spectrum is altered by sending a signal generated by a random number generator to a delay device and adding the output of the delay device from the output of the random number generator. Also, the spectrum is altered by seeding first and second identical random number generators, delaying the operation of the first random number generator, and adding the output of the delayed first random number generator from the second random number generator. | 09-25-2008 |
20080252500 | SYSTEMS AND METHODS FOR HIGH PRECISION FEEDBACK CONTROL IN CLOSED LOOP SENSORS - Improved methods and systems for feedback signals in a sensor system. An example method demodulates a sense signal using an analog demodulator and also demodulates the sinse signal using a digital demodulator. The difference between the result of the analog demodulator and the digital demodulator is determined and then integrated. A sensor feedback control signal is generated based on the integrated difference. | 10-16-2008 |
20080297805 | Spectral balancing system and method for reducing noise in fiber optic gyroscopes - Methods and apparatus are provided for reducing output noise of optical gyros. The apparatus includes a sensing system for circulating counter-propagating light beams and producing an output light beam, a coupler having multiple ports and supplying an input light beam to the sensing system, a first detector coupled to the coupler for detecting a rotation rate based on the output light beam, a second detector coupled to the coupler for detecting noise based on the input light beam, and at least one optical device coupled to one of the ports of the coupler. The optical device is configured to reduce a spectral mismatch between the input light beam received by the second detector and the output light beam received by the first detector. | 12-04-2008 |
20090059237 | DIGITAL FEEDBACK SYSTEMS AND METHODS FOR OPTICAL GYROSCOPES - A digital feedback system and for an optical gyroscope include a fiber optic sensing coil, an optical phase modulator, a photo detector and a processor. The sensing coil induces a phase differential between light waves traveling though the coil. The optical phase modulator causes a second phase differential between the light waves. The photo detector receive the light waves and outputs an intensity signal representing a phase difference between the light waves. The processor determines a rate of rotation of the fiber optic sensing coil based on the phase difference. for the system operates by generating a closed loop feedback signal, demodulating the signal to determine the phase difference, determining a rate of rotation, periodically incrementing a feedback ramp signal once every τ second period based on the rate of rotation, and resetting the feedback ramp signal when the ramp is incremented a predetermined number of times since a previous reset. | 03-05-2009 |
20090128826 | HIGH RESOLUTION IOC DRIVE AND METHOD FOR DRIVING FIBER OPTIC GYROSCOPES - Methods and system are provided for driving light through a sensing coil of an optical gyro. The system includes a photodetection circuit having an input for receiving an optical output from the sensing coil and having an output, and a signal processing circuit having an input coupled to the output of the photodetection circuit and having an output for supplying an output signal to modulate the sensing coil. The photodetection system produces a digital signal from the optical output. The signal processing circuit produces a feedback signal from the digital signal and adds a random number to the feedback signal to produce the output signal. | 05-21-2009 |
20100002239 | RFOG MODULATION ERROR CORRECTION - Systems and methods for performing modulation error correction. An example system applies common phase/frequency modulation to first and second laser beams, a first intensity modulation to the first modulated beam, and a second intensity modulation to the second modulated beam. Signals outputted are demodulated according to the frequency of the common phase/frequency modulation. Then the first of these demodulated signals is demodulated based on the frequency of the intensity modulation of the first beam, and the second of these demodulated signals is demodulated based on the frequency of the intensity modulation of the second beam. Then, rate of rotation is determined based on demodulated signals. Frequencies of the intensity modulations are unequal and not harmonically related, and intensity modulation encodes each light beam with a unique signature. | 01-07-2010 |
20100253948 | SYSTEMS AND METHODS FOR RESONATOR FIBER OPTIC GYROSCOPE INTENSITY MODULATION CONTROL - Systems and methods for improved resonator fiber optic gyroscope intensity modulation control are provided. In one embodiment, a resonant fiber optic gyroscope (RFOG) having a residual intensity modulation (RIM) controller comprises: an intensity modulator optically coupled to receive a light beam from a laser source modulated at a resonance detection modulation frequency; an optical tap device optically coupled to the intensity modulator; and a feedback servo coupled to the optical tap device and the intensity modulator, the demodulating feedback servo generating a sinusoidal feedback signal to the intensity modulator. The feedback servo adjusts an amplitude and phase of the sinusoidal feedback signal provided to intensity modulator based on a residual intensity modulation detected by the demodulating feedback servo. | 10-07-2010 |
20100309475 | METHOD AND AMPLIFYING STAGE FOR SUPPRESSING MODULATION DISTORTION RATE SENSING ERRORS IN A RESONATOR FIBER OPTIC GYROSCOPE - A device and a method for suppressing 2nd order harmonic distortion in a Resonator Fiber Optic Gyroscope includes driving a laser to generate at least one of a plurality of counter propagating laser beams traveling through a fiber optic resonator according to a modulated signal. The modulated signal can be represented by a polynomial having two terms, and each of the two terms is suitably multiplied by a coefficient and a constant. A modulation amplitude adjuster amplifies the modulation signal by an amplification factor as it is used to drive the laser. When the amplification factor is suitably chosen to represent a square root of a ratio of the constants, the total harmonic distortion in the RFOG is minimized. | 12-09-2010 |
20110141477 | LIGHT-PHASE-NOISE ERROR REDUCER - 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. | 06-16-2011 |
20110292396 | SYSTEM AND METHOD FOR ENHANCING SIGNAL-TO-NOISE RATIO OF A RESONATOR FIBER OPTIC GYROSCOPE - 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. | 12-01-2011 |
20120057167 | RFOG WITH OPTICAL HETERODYNING FOR OPTICAL SIGNAL DISCRIMINATION - 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. | 03-08-2012 |
20120307251 | HIGH PERFORMANCE HOLLOW-CORE OPTICAL-FIBER FILTER FOR OPTICAL ROTATION SENSING - A hollow-core optical-fiber filter is provided. The hollow-core optical-fiber filter includes a hollow-core 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 hollow-core optical-fiber filter also includes a first reflective end-cap positioned at the first end-face and a second reflective end-cap positioned at the second end-face. When an optical beam from a laser is coupled into one of the first end-face or the second end-face, an optical output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations. | 12-06-2012 |
20120307253 | OPTICAL FILTERING FOR RESONATOR-FIBER-OPTIC GYROSCOPES - 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. | 12-06-2012 |
20130057870 | SYSTEMS AND METHODS FOR RESONATOR FIBER OPTIC GYROSCOPE INTENSITY MODULATION CONTROL - Systems and methods for improved resonator fiber optic gyroscope intensity modulation control are provided. In one embodiment, a resonant fiber optic gyroscope (RFOG) having a residual intensity modulation (RIM) controller is provided. The controller includes an intensity modulator optically coupled to receive a light beam from a laser source modulated at a resonance detection modulation frequency, and an optical tap device optically coupled to the intensity modulator. The controller also includes a feedback servo coupled to the optical tap device and the intensity modulator, the demodulating feedback servo generating a sinusoidal feedback signal to the intensity modulator. The feedback servo adjusts an amplitude and phase of the sinusoidal feedback signal provided to intensity modulator based on a residual intensity modulation detected by the demodulating feedback servo. | 03-07-2013 |
20130107271 | SYSTEM AND METHOD FOR REDUCING ERRORS IN A RESONATOR FIBER OPTIC GYROSCOPE | 05-02-2013 |
20130271770 | RESONATOR FIBER OPTIC GYROSCOPE UTILIZING LASER FREQUENCY COMBS - 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. | 10-17-2013 |
20140044142 | LASER WITH TRANSMISSION AND REFLECTION MODE FEEDBACK CONTROL - 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. | 02-13-2014 |
20140049780 | LOW NOISE RESONATOR FIBER OPTIC GYRO - 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. The first-modulation frequency and the second-modulation frequency are adjusted so that sideband noise spectrum centered on the first and second modulation frequencies are from each other. | 02-20-2014 |
20140152994 | OPTICAL FREQUENCY COMB STIMULATED BRILLOUIN SCATTERING GYROSCOPE - 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. | 06-05-2014 |
20140204387 | NARROW BANDWIDTH REFLECTORS FOR REDUCING STIMULATED BRILLOUIN SCATTERING IN OPTICAL CAVITIES - 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. | 07-24-2014 |
20140211211 | RFOG WITH OPTICAL HETERODYNING FOR OPTICAL SIGNAL DISCRIMINATION - 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. | 07-31-2014 |
20140240712 | METHOD AND SYSTEM FOR DETECTING OPTICAL RING RESONATOR RESONANCE FREQUENCIES AND FREE SPECTRAL RANGE TO REDUCE THE NUMBER OF LASERS IN A RESONATOR FIBER OPTIC GYROSCOPE - A resonator fiber optic gyroscope (RFOG) is provided. The RFOG includes a gyroscope resonator having a clockwise input port and a counter-clockwise input port; a first laser configured to couple a clockwise optical beam into to the clockwise input port; a clockwise Pound-Drever-Hall modulation generator to modulate the clockwise optical beam with a resonance tracking modulation before the clockwise optical beam is coupled into the clockwise input port; bias correction electronics; FSR-detection-and-servo electronics including a switch communicatively coupled to the clockwise Pound-Drever-Hall modulation generator; a clockwise transmission detector configured to receive an optical beam output from the counter-clockwise input port and output signals to the bias correction electronics and the FSR-detection-and-servo electronics; and a second laser configured to couple a counter-clockwise optical beam into to the counter-clockwise input port, wherein the FSR of the gyroscope resonator is measured based on the Pound-Drever-Hall modulation of the clockwise optical beam. | 08-28-2014 |
20140369699 | SYSTEMS AND METHODS SIDEBAND HETERODYNING DETECTION - Systems and methods for sideband heterodyning detection are provided. In certain embodiments a system includes an optical resonator configured to allow light to resonate therein; at least one light source that is controlled to form multiple optical fields, wherein each field is phase or frequency modulated at a common modulation frequency and is at a different frequency. The system also comprises multiple heterodyne modulators that phase or frequency modulate a respective field in the multiple fields at a respective heterodyne frequency to form multiple sidebands, wherein the corresponding heterodyne frequency is different for each heterodyne modulator; at least one coupler that couples the multiple sidebands into the optical resonator; and a feedback control that is configured to detect the multiple sidebands transmitted out of the resonator to create multiple detected sideband signals and adjust frequencies of the plurality of fields based on the multiple detected sideband signals. | 12-18-2014 |
20150015892 | RFOG WITH LOW CHROMATIC DISPERSION - 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. | 01-15-2015 |
20150070707 | LASER WITH TRANSMISSION AND REFLECTION MODE FEEDBACK CONTROL - 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. | 03-12-2015 |