Abstract: A micro-electro-mechanical systems (MEMS) inertial measurement system facilitates accurate location and/or attitude measurements via passive thermal management of MEMS inertial sensors. Accuracy of the system is also improved by subjecting the inertial sensors to programmed single-axis gimbal motion, and by performing coarse and fine adjustments to the attitude estimates obtained by the system based on the programmed motion and on the passive thermal management of the sensors.

Abstract: A micro-electro-mechanical systems (MEMS) inertial measurement system facilitates accurate location and/or attitude measurements via passive thermal management of MEMS inertial sensors. Accuracy of the system is also improved by subjecting the inertial sensors to programmed single-axis gimbal motion, and by performing coarse and fine adjustments to the attitude estimates obtained by the system based on the programmed motion and on the passive thermal management of the sensors.

Abstract: A sensing coil assembly and method for attaching a sensing coil to a support structure are provided for a fiber optic gyroscope. The method comprises affixing a preformed adhesive to a mating surface of a mounting structure, and coupling an inner surface of the sensing coil to the mating surface of the mounting structure via the preformed adhesive. The mating surface is substantially cylindrical or conical. The sensing coil assembly comprises a hub having a mating surface, an optical fiber coil having an inner surface encircling at least a portion of the mating surface, and a preformed adhesive pattern affixing the mating surface to the inner surface. The mating surface of the hub is substantially cylindrical or conical.

Abstract: An optical waveguide device is provided for receiving light that has a guided mode and an unguided mode. The device comprises an optically transmissive substrate having first and second substantially opposite surfaces, an input end, and an output end. An optical waveguide region is disposed within the substrate and extends from the input to the output. A plurality of electrodes is disposed on the first surface at predetermined locations with respect to the waveguide region. The device includes a plurality of optical barriers each disposed proximate one of the first and second surfaces and positioned to block a different optical path of the unguided mode.

Abstract: A clock system for a fiber optic gyroscope is provided that includes a highly-tunable clock for the bias modulation and a separate asynchronous high-speed clock for the photodetector sampling. By separating the two clocks rather than using two derivatives of the same clock, the clock system and method can provide both the tunability objective of the bias modulation clock and the high-speed objective of the sampling clock, while using readily available, lower performance, radiation-hardened electronics parts.

Abstract: Methods and apparatus are provided for a seal assembly that includes a first plate, a second plate, and compliant material. The first and second plates each have a first side, a second side, and a channel extending therebetween. The channel includes a first cross-sectional area proximate the first side and a second cross-sectional area that is proximate the second side. The first cross-sectional area is greater than a second cross-sectional area. The compliant material is disposed between the first and second plates and is at least partially within the first plate channel and the second plate channel.

Abstract: A fiber optic gyroscope (FOG) includes a sensing coil with a particular magnetic sensitivity magnitude and direction with respect to the geometric axis of the sensing coil. The FOG also includes a plurality of magnetic compensators. Each magnetic compensator is fabricated so as to have a particular magnetic sensitivity magnitude and direction, the magnitude being comparable to that of the sensing coil, with large tolerances relative to the magnitude and direction. The compensators are positioned relative to one another and to the sensing coil such that the combined magnetic sensitivities of the compensators cancel the magnetic sensitivity of the sensing coil.

Abstract: Fiber optic gyroscope architectures that incorporate both (i) a WDM-based wavelength control and (ii) a wavelength reference based on a narrowband fiber Bragg grating (FBG), with the latter component providing significant improvement in the stability of the wavelength reference by calibrating out wavelength errors associated with a WDM-based wavelength control scheme.

Abstract: A phase jump amplitude and timing controller is used in a fiber optic gyroscope for suppressing color noise. The phase jump amplitude and timing controller inserts a phase/voltage jump into the feedback signal of the loop closure electronics of the fiber optic gyroscope. This phase/voltage jump breaks the repeated pattern of the drive signal. The IOC time-dependent characteristics are totally eliminated by the randomized feedback signal because no repeated signal is applied to the IOC. The randomized amplitude is preferably within the full ±? phase such that the optical errors average to zero. A fixed frequency higher than the interested spectral region can shift the color noise to higher frequency. A randomized frequency can spread the color noise over full spectrum, and totally eliminate the RDS. In other words, the color noise caused by the nonlinearity of the driving circuit and IOC spreads out over a wide range of spectrum such that no distinct frequency peaks are apparent in the spectral domain.

Abstract: A fiber optic sensing coil is formed by winding a non-coated optical fiber in a substantially circular loop. The non-coated optical fiber includes a core and a cladding. Once the non-coated optical fiber is wound, turns of the non-coated optical fiber are fused so that the cladding of the individual turns of the optical fiber are fused to one another at points of mutual contact.

Abstract: A phase jump amplitude and timing controller is used in a fiber optic gyroscope for suppressing color noise. The phase jump amplitude and timing controller inserts a phase/voltage jump into the feedback signal of the loop closure electronics of the fiber optic gyroscope. This phase/voltage jump breaks the repeated pattern of the drive signal. The IOC time-dependent characteristics are totally eliminated by the randomized feedback signal because no repeated signal is applied to the IOC. The randomized amplitude is preferably within the full ±&pgr; phase such that the optical errors average to zero. A fixed frequency higher than the interested spectral region can shift the color noise to higher frequency. A randomized frequency can spread the color noise over full spectrum, and totally eliminate the RDS.

Abstract: According to the preferred exemplary embodiments of the present invention, there is provided a phase jump amplitude and timing controller for suppressing the voltage-dependent errors responsible for the dead band. The phase jump amplitude and timing controller inserts a phase/voltage jump into the feedback signal of the loop closure electronics of the fiber optic gyroscope. The phase/voltage jump is provided at a frequency regular enough to ensure that the fiber optic gyroscope will not have enough time to settle into the dead band before the phase/voltage jump is supplied to the loop closure electronics. By providing a recurring phase/voltage jump with amplitude sufficient to move the signal out of the dead band, the loop closure electronics averages the voltage-dependent errors over the full feedback voltage range.

Abstract: According to the preferred exemplary embodiments of the present invention, there is provided a phase jump amplitude and timing controller for suppressing the voltage-dependent errors responsible for the dead band. The phase jump amplitude and timing controller inserts a phase/voltage jump into the feedback signal of the loop closure electronics of the fiber optic gyroscope. The phase/voltage jump is provided at a frequency regular enough to ensure that the fiber optic gyroscope will not have enough time to settle into the dead band before the phase/voltage jump is supplied to the loop closure electronics. By providing a recurring phase/voltage jump with amplitude sufficient to move the signal out of the dead band, the loop closure electronics averages the voltage-dependent errors over the full feedback voltage range.

Abstract: A true dV/dt voltage sensor having no need for a ground reference for measurement. The sensor is connected at two places on the electric line to be measured. The voltage wave has a delay between the two places on the line and the difference is sensed and converted into a voltage measurement. Another approach is to connect the sensor at one place on the electric line. This approach has the second connection through a phase delay circuit that has an input connected to the same place. The delay between the one connection and the output of the phase delay circuit is sensed and converted into a voltage measurement. The sensed difference is a voltage, which is applied across a device, such as an electro-optic crystal, an integrated optic circuit (IOC) or a Mach Zehnder interferometer, which is a light medium that has a birefringence or an index of refraction that varies with changes of applied voltage. The variation of birefringence changes the polarization state of the light going through the device.

Abstract: A design for an environmentally robust fiber depolarizer for a fiber optic gyroscope is disclosed. The design comprises; substantially a clockwise propagating leg and a counterclockwise propagating leg, distally coupled at opposite ends of a gyroscope sensing coil, said depolarizer fiber leg wound in a that is rotation insensitive pattern and that is also a symmetrical winding pattern. Moreover, axial, radial and embedded sensing coil mounting methods for the fiber depolarizer to reduce the depolarizer sensitivity to thermal variations are also disclosed. Specific attention to the design of the fiber depolarizer of a gyroscope provides enhanced immunity to the stress of environmental variation.

Abstract: A fiber optic gyroscope having polarization error-correcting modulation. Polarization errors originate from the interference of primary waves and secondary cross-coupled waves. Although these error signals are very difficult to remove modulation signals may be applied to the integrated optics chip that minimize the total error over a period of time. By providing distinct but inter-related modulation signals to opposing inputs of the sensing coil, the various polarization errors can be averaged to zero over the period of the modulation signals.

Abstract: Vanadium dioxide (VO.sub.2) based infrared spatial light modulators (SLM) in four embodiments are disclosed:(1) A VO.sub.2 thin film is deposited on a planar diode array. Each diode constitutes a "pixel" of the SLM. Power provided to a diode permits accurate thermal control about the thin film's hysteresis. Initial biasing of the diode array is required to the base of the VO.sub.2 's hysteresis curve.(2) & (3) VO.sub.2 is deposited on a thermoelectric array which can be an array of doped lines of p and n type material or a conductive material between two electrical contacts. The pixels have the ability to both heat and cool the VO.sub.2 film, thereby allowing the array to be operated in a bistable mode. Bistable operation requires external biasing to the center of the VO.sub.2 's hysteresis curve.(4) A VO.sub.2 thin film deposited on a substrate which is spaced a distance, L, from an array of vertical-cavity surface-emitting lasers for heating the VO.sub.2.