Abstract: A sensor coil for a fiber optic gyroscope. At least one dummy layer forms an integral structure with, and shares the thermal expansion characteristics of, a potted coil comprising a plurality of layers of windings of a first optical fiber. In a gyroscope, the potted coil is arranged to receive the output of a source of optical energy as a pair of beams that counter-propagate therein and to provide the resultant interference pattern, as gyro output, to a detector. The dummy layer displaces layers or windings of the potted coil from regions likely to contribute to Shupe bias effects.

Abstract: A direction finding antenna system includes a plurality of monopole elements disposed symmetrically around a center of a circular ground plane at the same radial distance from the center and a multimode combiner connected to the monopole elements to provide one or more mode outputs. A phase difference detector determines phase differences between selected ones of the mode outputs to provide azimuth bearing of a detected object. Typically, four or eight monopole elements are used. Placement of the inherently narrowband monopole elements in a bicone structure having a polarizer grid extends the useful bandwidth. Multiband coverage is achieved with a plurality of such antennas connected by a feed cable positioned on the polarizer grid to avoid interference.

Abstract: A method for poling a ferroelectric crystal includes heating the crystal to a temperature above its Curie temperature and applying a first selected voltage to the electrodes to apply an electric field to the crystal. The temperature of the crystal is then reduced to a temperature below the Curie temperature of the crystal, and a second electric field having polarity opposite to the polarity of the first electric field is applied to the crystal. Application of the second electric field reduces nonuniformity in ion concentration across the crystal.

Abstract: A narrow-band antireflective coating is comprised of a multilayer dielectric film formed on a dielectric substrate. The antireflective coating is initially formed so that its outer layer has a thickness greater than the thickness required for antireflection. The reflectivity is monitored while outer layer is reduced in thickness to reduce the thickness of the outer layer to reduce the reflectivity.

Abstract: The invention is a vibratory rotation sensor comprising a resonator and a resonator housing and a method for controlling and reading out the sensor utilizing multiplex electronics. The resonator is a rotationally-symmetric thin-walled object that can be made to vibrate in a plurality of standing-wave modes. One or more electrodes are attached to a surface of the resonator and connect to a single output port The housing has a plurality of attached electrodes in close proximity to the resonator electrodes. The method for controlling and reading out the vibratory rotation sensor includes applying driving voltages to the housing electrodes and determining the parameters of the standing waves by performing operations on the resonator signal that emerges from the resonator output port. A driving voltage may include either an excitation voltage or a forcing voltage or both.

Abstract: The invention is a method for applying forces to the resonator of a vibratory rotation sensor (VRS) by establishing an ac voltage between conducting regions of a surface of the resonator and one or more forcer electrodes opposing the conducting regions. The method comprises the steps of generating a first ac voltage having a first frequency and a first phase, generating a second ac voltage having a second frequency, and establishing the difference of the first and second ac voltages between conducting regions of a surface of the resonator and the one or more forcer electrodes. The first and second ac voltages are synchronized to the displacement of a point on the resonator when the resonator is vibrating. The ratio of the vibrational frequency of the VRS to either the difference or the sum of the first and second frequencies is a ratio of integers.

Abstract: A power boosted source of broadband optical power comprising a broadband light source, optical fiber amplifier and a relative intensity noise reduction system. The optical fiber amplifier amplifies the power level of the optical input signal to provide a power boosted source of broadband optical power out of an output port. A coupler samples a portion of the broadband optical power out of the output port as a sample portion signal. A detector and transimpedance amplifier detect the optical signal and provide a buffered signal having an instantaneous amplitude that faithfully characterizes the intensity of the sample portion signal. A bandpass amplifier amplifies the buffered signal and provides an output control signal to a light source responsive to a composite bias and control current for providing an output optical signal. The output optical signal is coupled to the input of the optical fiber amplifier to be the optical input signal to the optical fiber amplifier.

Abstract: The invention is a method for determining the relative position and velocity of a second vehicle with respect to a first vehicle. The method is practiced on board the second vehicle and utilizes a plurality of satellite transmitters and an inertial measurement unit on the second vehicle. The first vehicle has available a plurality of data items consisting of the first vehicle's measured position, measured velocity, and specific-force acceleration. The second vehicle has available data items consisting of the second vehicle's measured position, measured velocity, specific-force acceleration, autonomous position, autonomous velocity, autonomous position correction, and autonomous velocity correction. The measured position and measured velocity are determined utilizing the radio signals from a plurality of satellite transmitters and the specific-force acceleration is obtained from an inertial measurement unit.

Abstract: Compact triaxial multioscillator configurations are based upon frames of rhombic dodecahedron and truncated octahedral shapes as taught by U.S. Pat. No. 4,795,258. Three non-planar cavities, each comprising four intersecting bores, intersect within the frames. External Faraday rotator assemblies comprising reverse mirrors and associated permanent magnets in differing configurations eliminate the need for intracavity elements to obtain nonreciprocal splitting. In the rhombic dodecahedron-shaped frame, external Faraday rotator assemblies are fixed to three planar faces at each of which pairs of segments of each of the internal nonplanar cavities converge. In the truncated tetrahedral frame, a single external Faraday rotator assembly is fixed to the single planar face at which pairs of segments of the three nonplanar cavities converge in a pattern forming the apexes of a centered equilateral triangle.

Abstract: The invention is a method for obtaining observables for input to a Kalman filter process which determines the attitude (roll, pitch, and heading) of a platform. The invention utilizes an inertial measurement unit (IMU) attached to the platform and an associated processor, a plurality of signal receiving antennas attached to the platform, and a plurality of satellite transmitters. The heading of the platform as determined by the IMU and its associated processor by themselves can be significantly in error. A comparison of the values of an attitude-sensitive function of the ranges from the platform antennas to different groupings of satellite transmitters obtained first by using IMU data and second by using the measured phases of the satellite-transmitter signals received at the platform antennas, a very accurate value for the range function is obtained. This accurate value of the range function is used in a Kalman filter process to obtain very accurate values for platform attitude.

Abstract: An amplifier method and apparatus for use with optic systems utilizing a fiber optic circulator to direct input signals to a splitter that splits the copropagating pump light and input signals into two equal parts for simultaneous introduction into the two opposite ends of the active gain fiber. Half of the pump light and half of the signal are propagating through the active fiber in a clockwise and counterclockwise direction at the same time. This bidirectional propagation results in a more uniform excitation along the entire length of the active fiber, providing uniform stimulation of photon emission at both ends, causing significantly reduced noise and higher gain of the signal. Two half-amplified signals are combined and supplied to the circulator that provides the amplified output signal without any residual pumping light at the input or the output port of the circulator.

Abstract: A daylight readable LCD which may be used to communicate information as high contrast images (static or dynamic, color or monochrome) in bright ambient lighting conditions over a wide temperature range in direct sunlight. A contrast enhancement filter assembly is disposed at the interface between a backlit display and a user. The contrast enhancement filter assembly includes a triple bandpass contrast enhancement filter that preferably passes light efficiently in each of the red, green, and blue primary wavelengths and substantially absorbs all other wavelengths. Display contrast is increased because of the absorption of incident light having wavelengths that differ from the light produced by the internal backlight source within the display. This results in the display having a blacker background and enhanced purity of the color primaries. The display element is disposed generally behind the contrast enhancement filter assembly.

Abstract: A highly efficient motor driver circuit of an electronic controller for linear cryogenic coolers operates directly from a variable power supply, such as a battery, without the need for the voltage regulator control circuit of the prior art. Elimination of the prior art voltage regulator ensures a higher efficiency motor driver circuit of the electronic controller. Both open-loop and closed-loop controllers electronically control the motor driver circuit. The open-loop controller protects against temperature sensor failure, and will limit maximum motor power as a function of system ambient temperature. The closed-loop controller regulates the temperature of the cold finger accurately to a preset value, using feedback from a temperature sensor along with a novel pulse-width modulation concept for modifying motor drive waveforms.

Abstract: A ring laser gyroscope having an alternating Faraday bias includes mode combining apparatus arranged to cause interference between the modes that propagate within the cavity. Signal separating apparatus separates a signal indicative of rotation of the frame from other components of the combined intensity signal. The signal separating apparatus produces two signals indicative of the light intensity in the interference pattern of the combined modes. These two signals have a 180.degree. phase difference in corresponding components that are dependent upon the geometric bias caused by the non-planar optical path to produce a rotation signal that is independent of the spatially uniform interference fringes caused by the geometric bias.

Abstract: A flexible interlink for joining a first sensor of the type that includes a cylindrical mandrel for mounting a common optical fiber to a second sensor of a hydrophone that includes a cylindrical mandrel for mounting said fiber. The interlink includes an integral molded body of flexible material. Enlarged diameter ends are joined to the link by outwardly-tapered transition members. Resilient metal washers are fixed to the ends for locking onto the sensor. The washer includes radial elements that abut corresponding radial elements of the end. The radial elements of the washer are outwardly inclined, of greater length than the corresponding radial elements of the end and exceed the inner diameter of the sensor from tip to tip.

Abstract: An electrical slip ring base is constructed of flexible and moldable or extrudible material so as to be capable of being formed into a variety of profiles or shapes. A rigid backing or hub stiffens or reinforces the base member. Any form of conductive rings can be used, and the base member can be formed to accommodate them.

Abstract: An optical velocity measuring device includes a pair of V/H sensors effectively located at two different distances from a moving object. Each sensor is used to determine an image velocity and a corresponding angular velocity of the object. The angular velocity measurements and the difference in distance or optical path length of the individual sensors are used to determine the absolute linear tangential speed of the object without determining the absolute distance to the object.

Abstract: The invention comprises a reticle assembly for an optical sight. In accordance with one embodiment of the invention, a reticle assembly (58) may comprise a housing (302) having a first slot (322) formed along an inside surface (304) by a first set of opposing side walls (318). A cross slide (330) may disposed in the first slot (322). The cross slide (330) may include opposing edges (334) engaging the first set of opposing side walls (318). The cross slide (330) may include a second slot (340) formed by a second set of opposing side walls (346) substantially normal to the first set of opposing side walls (318). A reticle holder (350) may be disposed in the second slot (340). The reticle holder (350) may include opposing edges (358) engaging the second set of opposing side walls (346). The reticle holder (350) may include a viewing aperture (354). A reticle (300) may be coupled to the reticle holder (350) in alignment with the viewing aperture (354).

Abstract: A focusing system for a helix TWT includes a polepiece structure for conducting magnetic flux to a drift tube of the TWT in a first general direction and conducting the magnetic flux from the drift tube in a second general direction perpendicular to the first general direction. Radially magnetized permanent magnets are disposed at outer portions of the polepiece structure and supply the magnetic flux. A first pair of the magnets have a first direction of polarity, and a second pair of the magnets have a second direction of polarity opposite to the first direction. An outer shell encapsulates the polepiece structure and the magnets, and provides a magnetic flux return path. An electron beam travels in the drift tube and the magnetic flux provides focusing for the electron beam.

Abstract: A potted sensor coil for a fiber optic gyroscope includes an inter-layer stress relief layer of lubricating material. The coil is wound into a known pattern. Various coil configurations can be realized in which a coating layer of lubricant relieves stressing at the interface between the outer jacket of the fiber and the coil potting material.