Abstract: A multioscillator ring laser gyro having a Faraday Cell with an optical wedge in one of its branches. Variations in the MCDL of the optical wedge with temperature are reduced to substantially zero. The internally specularly reflected and backscattered beams from said primary beam have path lengths such that the internally double-bounced reflected and scattered beams of each mode have path lengths wherein the differences between the mode directions are adjusted in a particular manner to reduce cyclic variations with temperature in MCDL substantially to zero.

Abstract: A ring laser gyro frame of ceramic material having therein lithium ions for dimensional stability over a change in temperature. Either a slot is formed in the ceramic material, a secondary negative electrode is placed spaced apart from the ceramic material to warp the electric field, or both.

Abstract: A ring laser gyro having a ring laser that preferably has four legs and four corner mirrors. At least one of the corner mirror is partly transmissive, and the transmitted beam is sensed and converted into a digital signal. The digital signal is fed back in two computer loops to at least one digital-to-analog converter, and thence to a transducer which drives at least one corner mirror inward and outward. One of the computer loops includes a stepped demodulator having four steps per cycle. The steps have voltages at the operating voltage of the transducer, that voltage plus an increment, the operating voltage, and that voltage less a decrement. The first loop sends an operating voltage to the digital-to-analog converters. The second loop demodulates the beam signal at a second harmonic of the demodulation of the first loop to produce a voltage signal which controls the amplitude of dithering of the movable mirrors.

Abstract: A method for producing a narrow band anti-reflective film on a substrate, and the film produced by that method.Uses the concept of considering a multifilm dielectric to be an equivalent two-film dielectric, then removing a predetermined thickness of the outer, lower dielectric, film to cause the complete multifilm to become anti-reflective.When limited numbers of film materials are available, uses an EIL or effective index layer concept to obtain a predetermined index of refraction which improves the tolerance of the reflection of an anti-reflective film to film thickness errors.

Abstract: The invention is a hinge assembly made of two parts, specifically for an accelerometer. The first part is adapted to be attached, either directly or through a bracket, to an inertial acceleration sensor. The second part is adapted to be rigidly attached to an apparatus whose acceleration is to be measured. The two parts are connected by a flexible hinge.The invention resides in the placement of the hinge and in the attaching means for the second part of the hinge frame as well as in the method for fabricating the novel attaching means.The hinge is not attached to the center of the opposing edges of the first and second parts of the hinge frame. It is attached to one end of those opposing sides at a first region of the second part of the hinge frame. The hinge line is generally parallel to those opposing sides.The second part of the hinge frame is clamped only in a second region away from the hinge.

Abstract: An acoustic transducer with a piezoelectric acoustic oscillator member that has a first surface with a common electrode, and a second surface with a predetermined electrode pattern. In some instances the electrodes are individually connected off of the transducer. In other instances some of the electrodes are connected together in sets. Each set is then connected off of the transducer. The individually connected electrodes are connected to an adjacent pedestal supporting a pad that is adapted to be soldered or wired to a wire member. When the electrodes are connected together in sets, the connecting member is supported on a plateau or pedestal so that a wire may be connected to any part of the connector. In one preferred embodiment, where two sets of electrodes are connected to two connectors, the connectors are parallel conductive side rods positioned on opposite edges of and adjacent to the oscillator member.

Abstract: To prevent a supported block, particularly a ring laser block, from translating, rotating, or being stressed with changes in temperature, the block to be supported carries a plurality of, typically four, coplanar radially-outward-extending circularly cylindrical posts. The posts are grasped by compliant axially-split sleeves or mounts which engage posts. The mounts are supported by a surrounding substantially circular frame. The mounts are substantially equiangularly positioned around the frame, and the posts are correspondingly positioned upon the block. The frame is surrounded by a case which is adapted to be fastened to another structure such as a vehicle or gimbal. At points angularly positioned around the frame, substantially equiangularly positioned from the adjacent sleeve fixtures, the frame is rigidly attached to the case. The mounts and the frame are both made of a material, typically Invar, having a known temperature coefficient of expansion.

Abstract: The apparatus of this invention is a composite combining prism for combining the beams of a ring laser gyro. It uses a composite prism whose trunk is fabricated of two substantially identical juxtaposed sub-prisms having beam splitters in the region where laser beams cross their common boundary. The beam splitter regions are very thin dielectric films, typically no thicker than a fraction of a wavelength of the laser light. Dielectric films, such as titanium dioxide, are used for the splitters so that the geometrical path lengths of interfering beams are almost exactly the same. To make the path lengths optically the same, the two sub-prisms and the substrate of the partly transmitting corner mirror of the ring laser preferably have the same index of refraction. In a first embodiment, the outwardly-extending trunk of the assembled composite prism is substantially rectangular in cross-section.

Abstract: The apparatus of this invention uses a two-branched linear gas laser having two end mirrors and a third mirror positioned at a bend in the two-branched laser cavity. The laser cavity is bent through an angle, .theta., usually ninety degrees. With a bent cavity, frequency splitting occurs, and that splitting is a function of the angle .theta.. The end mirrors and laser cavities are supported upon two beams relative to the third mirror, and or both of these beams are cantilevered relative to the third mirror. Each flexible beam supports a proof mass. Under acceleration, the angle .theta. changes in a reversible and reproducible manner. The beams are converted into properly oriented planar polarized waves, and the specially polarized beams then are delivered to laser beam sensors to produce electrical output signals that are a measure of the frequency splitting between the two laser modes and a measure of sensed acceleration.

Abstract: A compact three axis ring laser gyroscope having six laser corner mirrors which are positioned on the faces of a parallelopiped laser block, and method for making. Preferably the laser block is a cube. The laser block has a plurality of conduits therein for defining a plurality of closed laser beam-paths for guiding counterpropagating laser waves. Each laser beam-path has a gain medium therein and is formed to define a sensing axis for detection of rotations of the laser block. A single cathode is positioned inside the laser block, preferably substantially at its geometric center, and a plurality of anodes are mounted to the laser block and spaced apart from the cathode. A ion flow path is formed between each anode and the cathode such that application of a suitable electrical potential difference between the anodes and the cathode produces counterpropagating laser beams in each laser beam-path.

Abstract: A bulk acoustic wave spectrum analyzer and channelizer, using bulk acoustic wave beams in a body of material having the property of conducting bulk acoustic wave beams, including acoustically reflecting surfaces. An input transducer is positioned upon one surface of the body for launching acoustic beams into the body. At least one output transducer set, including a plurality of aligned, juxtaposed electrodes are placed on the outer surfaces of each of the output transducers of the transducer sets.

Abstract: Apparatus for producing a three phase signal from two or three optical beams at different optical frequencies, such signal having a frequency equal to the difference frequency or frequencies between the optical frequencies of said beams including, preferably, an equal energy single mode fiber optic coupler and optical focusing means, such as gradient index rods, for directing said light beams onto light conducting fibers, preferably single mode fibers, thence through the coupler, thence onto light detectors to produce a substantially balanced three phase electrical signal at said difference frequency or frequencies.In a preferred embodiment, the light beams are two in number, connected to only two input ports of said coupler, and the light beam sources are the output beams of counter- propagating ring laser beams in a ring laser gyro.

Abstract: A bulk acoustic wave angle-of-arrival processor in which a bulk acoustic body having the property of conducting bulk acoustic wave beams has formed and defined thereon at acoustically reflecting and focusing surface, the acoustically reflecting surfaces including a portion of one concave inward surface, positioned to receive acoustic beams launched from an input transducer.The body has at least one output transducer set, and each has a plurality of juxtaposed directed finger-electrodes aligned in a row perpendicular to the long direction of the electrodes, and positioned to receive steered beams from at least one of the reflecting surfaces.An input transducer set is positioned upon one surface of the body to steer beams into the body toward at least one of the reflecting and focusing surfaces.The input transducer set has individual electrodes on its outer surface which are positioned and spaced to the same pattern as the respective antennas to which they are attached.

Abstract: A plurality of accelerometers enclosed within a housing and mounted upon a thermally conductive support member, a temperature sensor and an optional temperature controlling element within the housing. Each of the accelerometers having two precision surfaces thereon, angular positioned by a predetermined angle, typically ninety degrees, between such surfaces.

Abstract: A vibrating multisensor, each using two accelerometers which are vibrated along straight lines perpendicular to their sensing axes. The sensing axes are co-linear, the accelerometers are vibrated in phase opposition along parallel axes. The accelerometers preferably use a proof mass and flexure suspension made on a silicon wafer sandwiched between two other wafers that carry electrodes both for sensing displacement and forcing of the central accelerometer wafer.

Abstract: A vibrating multisensor, each using two accelerometers which are vibrated along straight lines perpendicular to their sensing axes. In one embodiment, the sensing axes are co-linear, and in another embodiment the sensing axes are perpendicular. The accelerometers preferably use a proof mass and flexure suspension made on a silicon wafer sandwiched between two other wafers that carry electrodes both for sensing displacement and forcing of the central accelerometer wafer.

Abstract: Apparatus and method for dithering ring laser angular rotation sensors, including a plurality of such sensors with substantially identical natural dither frequencies and having different sensor axes mounted upon a resilient structure; applying energy to dither such sensors; the energy being connected and disconnected from the dithering of each sensor in response to the amplitude of dither of that particular sensor to minimize lock-in; and frequency or phase modulating the energy applied to dithering to avoid continued uni-directional coning effects.

Abstract: Apparatus for maintaining the length of a ring laser path and of its branches substantially constant during temperature and stress changes, using forcers directed outward toward the apexes of the ring laser and perpendicular to the laser path.

Abstract: An improved laser gyro dither mechanism utilizing a three-spring suspension system which not only isolates dither vibrational energy generated within the gyro and prevents that energy from passing to the mounting case of the laser, but which, additionally, eliminates possible pendulous action by the suspended gyro mechanism. The gyro's ring laser is mounted about a center post in its case. A first spring member is connected between the ring laser an the center post at the top of the post. A second spring member is connected between a counterweight and the centerpost on the bottom of the post. A third spring member is connected between the ring laser and the counterweight on the bottom of the post to complete the suspension system.

Abstract: A laser angular rate sensor has four corner mirrors forming a substantially square ring laser to reflect two counterpropagating laser beams around a closed path. Dither vibrators are interconnected to two consecutive mirrors in the path to oscillate perpendicularly to their mirror surfaces with 180 degree phase opposition. In one embodiment the mirror displacement is controlled to an amplitude of substantially 0.541 times the wave length of the laser light. In a second embodiment the mirror displacement amplitude is controlled to minimize the alternating component beat amplitude between one of the two laser beams and light scattered by the mirrors from the other beam. A microprocessor responsive to the output beat frequency of the ring laser gyro disconnects the dither drives when the amplitude of the input angular velocity to be measured exceeds a predetermined value greater than the maximum limit of the lock-in range of the gyro.