Abstract: One embodiment of the invention includes an atomic clock system including an alkali beam cell and an interrogation system configured to generate an optical pump beam and at least one optical probe beam that illuminate a detection chamber of the beam cell to pump evaporated alkali metal atoms. An optical detection system can provide a microwave signal to the detection chamber and can measure an intensity of the optical pump beam to determine a transition frequency corresponding to optimum photon absorption of the evaporated alkali metal atoms. A photodetection system can measure an intensity of the at least one optical probe beam and to generate an intensity signal that is provided to the optical detection system to substantially cancel Doppler broadening of the transition frequency resulting from non-orthogonal planar movement of the evaporated alkali metal atoms relative to the optical pump beam and the at least one optical probe beam.

Abstract: An apparatus in one example comprises a polarization filter and a polarization analyzer. The polarization filter comprises a first polarization axis. The polarization analyzer comprises a second polarization axis. The polarization filter is configured to polarize detection light for a nuclear magnetic resonance (NMR) cell along the first polarization axis. The polarization analyzer is configured to receive the detection light from the NMR cell and pass a portion of the detection light to a processor for determination of angular rate information. The portion of the detection light passed to the processor is based on an orientation of the second polarization axis relative to the first polarization axis. The orientation is selected to maximize a signal-to-noise ratio of the detection light.

Abstract: A self-calibrating gyroscope system provides improved estimates of, and compensation or calibration for, scale factor errors and bias errors. The gyroscope system employs a plurality of gyroscope units having sense or input axes in a mutually non-parallel arrangement. A Mode Reversal technique is used to obtain an estimate of bias error for a selected gyroscope. A Random Closed-Loop Scale Factor technique is used to obtain an estimate of scale factor error for a selected gyroscope. Because the Mode Reversal technique temporarily disrupts operation of the affected gyroscope, each of the gyroscopes may be taken offline temporarily, in turn, for calibration, and thereafter returned to normal operation. Because at least one redundant gyroscope is provided, when a selected gyroscope is offline, rate information from the remaining operating gyroscopes can be used to derive a reference rate about the axis of the offline gyroscope.

Abstract: One or more first portions of a reduced optical material wafer are covered with a masking layer that leaves uncovered one or more second portions of the reduced optical material wafer. The reduced optical material wafer is exposed to an oxidizing atmosphere to reverse a reduction of the one or more second portions of the reduced optical material wafer that makes the one or more second portions receptive for implementation of one or more optical waveguides.

Abstract: One embodiment of the invention includes an alkali beam cell system that comprises a reversible alkali beam cell. The reversible alkali beam cell includes a first chamber configured as a reservoir chamber that is configured to evaporate an alkali metal during a first time period and as a detection chamber that is configured to collect the evaporated alkali metal during a second time period. The reversible alkali beam cell also includes a second chamber configured as the detection chamber during the first time period and as the reservoir chamber during the second time period. The reversible alkali beam cell further includes an aperture interconnecting the first and second chambers and through which the alkali metal is allowed to diffuse.

Abstract: The method and apparatus in one embodiment may have: providing a two-dimensional axisymmetric oscillator having a beam containing two principal elastic axes and two principal damping axes; driving the beam with drive components to oscillate across corners of the beam at approximately 45 degrees to sides of the beam, the drive components having forcer components that provide drive and pickoff components that provide feedback; and oscillating the beam in a normal mode and a reverse mode.

Abstract: The apparatus in one embodiment may have capacitive bulk acoustic wave disk gyro operated in a closed loop mode. A self-calibration system may be operatively coupled to the capacitive bulk acoustic wave disk gyroscope. Self-calibration of gyro bias of the gyro may be implemented by interchanging an anti-nodal axis with a nodal axis of the gyro.

Abstract: At least two light beams with polarization diversity are generated that each carry a representation of the same information. Separate optic fibers carry each of the at least two beams through a region subject to vibration to a remote location where the information is recovered by an optical receiver based on the separate light beams. Using separate fibers to carry polarization diverse information minimizes polarization noise at the optical receiver due to vibration of the fibers.

Abstract: Systems and methods are provided for automatically detecting sonar contacts. The system comprises a data analyzer that integrates the raw data from a plurality of sonar detectors over a predetermined period of time, thereby providing integrated data characterizing a sonar image on a sonar display. A Hough transform module is configured to employ a Hough transform algorithm that transforms at least a portion of the integrated data to detect a substantially straight line in the sonar image.

Abstract: The Inner-Forcer milli-Hemispherical Resonator Gyro (mHRG) is a small, low cost, high performance gyroscope. It may have an extremely simplified design, with in one embodiment of the present method and apparatus only five major parts total, with most parts filling multiple functions. The method and apparatus in one embodiment may have: a resonator; and a body operatively coupled to the resonator, the unitary body integrally having electrodes, an electrode support unit, a weld ring and a plurality of electrically conductive pins, the plurality of electrodes operatively coupled to the electrically conductive pins.

Abstract: The method and apparatus in one embodiment may have: operating one of two resonators of a class II coriolis vibratory gyro in a closed loop mode and another of the two resonators in an open loop whole angle mode; sensing an angular rate by each of the two resonators; calibrating the scale factor of the closed loop resonator to yield the same integrated whole angle as measured by the open loop resonator; reversing operation of the two resonators such that the one of two resonators is operated in an open loop mode and the another of the two resonators in a closed loop whole angle mode; and alternately proceeding between open and closed loop operation of the two resonators, thereby self-calibrating scale factors respectively of the two resonators.

Abstract: The method and apparatus in one embodiment may have: a gyro housing containing a bias field; a bias field that generates a stable axial magnetic field; Xenon or other gas contained within at least a portion of the axial magnetic field, Xenon or other gas nuclear spins precessing at a constant angular rate with respect to the gyro housing in response to the axial magnetic field; wherein reversing a polarity of the bias field reverses a polarity of the magnetic field and a polarity of the precession of the Xenon or other gas nuclear spin, and wherein a reversing of the polarity of the gyro scalefactor thereby results without reversing a polarity of the gyro bias.

Abstract: A first navigation unit of an apparatus in one example comprises a hybrid global positioning system (GPS)/inertial navigation system (INS) component. The hybrid GPS/INS component provides first GPS information and first INS information for the first navigation unit. The first navigation unit is configured to receive second GPS information and second INS information from a second navigation unit. The second navigation unit comprises a GPS component configured to determine a double-differenced GPS carrier phase measurement through employment of the first GPS information and the second GPS information. The first navigation unit comprises a relative Kalman filter configured to update an INS error estimate for an estimate of a relative position between the first and second navigation units based on the double-differenced GPS carrier phase measurement and the first and second INS information.

Abstract: First and second inertial instruments have parallel sense axes and produce respective first and second output signals using associated first and second scale factors. Bias errors are estimated using the change in state of sign of the first and second scale factors. A substitute scale factor is determined to be an equivalent of the second scale factor and is based on the first scale factor and a difference between the first and second scale factors. Errors in the second scale factor are calculated based on the first scale factor and the substitute scale factor where a sign of one of first and second scale factors changes going from the first time interval to the succeeding time intervals. First and second corrected output signals are generated based on the respective first and second output signals and correction of the second scale factor error.

Abstract: A fiber optic sensor includes a housing having first and second end plates with a sidewall extending therebetween with the sidewall having an inwardly facing groove. A flexural disk having a central passage therethrough has an outer edge portion mounted in the inwardly facing groove in the housing. The flexural disk has a stepped thickness that is thinner at the outer edge portion than at a region spaced apart from the housing. A first fiber optic coil is mounted on a first side of the flexural disk in the thicker region of the flexural disk, and a second optical fiber is mounted on a second side of the flexural disk opposite the first fiber optic coil. The first and second fiber optic coils are optically coupled together by a fiber optic coupler to form an interferometer that produces an output signal in response to axial acceleration of the flexural disk.

Abstract: The method and apparatus in one embodiment may have: a sensing element for an accelerometer having a bias, the sensing element having a rectangular plate supported by flexures which allow rotation about a transverse center line thereof; a center of mass (CG) of the sensing element having two stable positions, one on each side of an axis of rotation defined by a centerline of suspension; a secondary mass within a proofmass translates in-plane to move the center of mass to thereby effect a self-calibration mechanization that continuously measures and nulls the accelerometer's bias under dynamic operating conditions.

Abstract: A closed loop scale factor estimator of an apparatus in one example is configured to compare a measured flex angle of a hemispherical resonator gyroscope (HRG) with a demodulation angle signal to estimate a force-to-rebalance (FTR) scale factor for the HRG, wherein the demodulation angle signal corresponds to an integral of a non-uniform rate signal applied to the HRG.

Abstract: A circuit board mounting system in one example comprises an improved mounting system for a circuit board disposed between housing elements, wherein the improvement comprises a plurality of slots formed in the circuit board and a plurality of bushings disposed within the slots, such that the housing elements rest on opposed ends of the bushings, and the circuit board moves in a plane substantially parallel to its mounting surfaces in response to changes in temperature, thus reducing thermal stress.

Abstract: The method and apparartus in one embodiment may have the steps of: providing a two-dimensional axisymmetric oscillator having a beam containing two principal elastic axes and two principal damping axes; driving the beam with drive components to oscillate; driving, during a first period, the beam along a drive axis of the beam in a direction normal to one pair of faces of the beam while Coriolis coupled vibration is sensed along a sense axis of the beam normal to an orthogonal pair of faces of the beam; reversing, during a second period, drive and sense axes driving the beam; reducing a bias of the beam to zero; and reducing a quadrature of the beam to zero.

Abstract: At least two light beams with polarization diversity are generated that each carry a representation of the same information. Separate optic fibers carry each of the at least two beams through a region subject to vibration to a remote location where the information is recovered by an optical receiver based on the separate light beams. Using separate fibers to carry polarization diverse information minimizes polarization noise at the optical receiver due to vibration of the fibers.