Abstract: A ring laser gyro system having at least one fixed mirror, and two movable mirror assemblies, for causing a pair of laser beams to counter-rotate therebetween, including amplitude control circuits and a phase control circuit for causing the movable mirror assemblies to sinusoidally oscillate at the same amplitude and frequency, but 180.degree. out of a phase with one-another, to substantially eliminate lock-in.

Abstract: A piezoelectric actuator for use in controlling the path length, for example, in a ring laser gyro is made of two piezoelectric discs attached to a metallic structure for exerting a push-pull force thereon to move the metallic structure in an oil can fashion. The piezoelectric actuator is attached to a dual diaphragm mirror assembly in such a way as to impart a strictly linear motion to the mirror assembly without any deliterious rotational effects. The actuator can easily be optimized for varying diaphragm stiffness by adjusting the thickness of the metallic structure to which the piezoelectric discs are attached. The mirror assembly and actuator are designed to minimize the influence of temperature changes on the position of the path length mirror.

Abstract: A signalling device with a long audible range is described, which is intended for underwater communication between divers. The device consists of a compact and lightweight horn and a rubber bulb. The horn, which works independently from a diver's supply of breathing air, is filled with water and operated by manually squeezing the rubber bulb.

Abstract: In a monolithic gyro assembly having three ring laser gyroscopes each measuring the inertial rotation of an axis, a polyhedron having three facets is used as the beam combiner for the gyroscope. On one of the facets is mounted a fringe detector for providing inertial rotation information for the gyroscope. On the remaining two facets, on either side of the fringe detector facet, are mounted beam power monitoring diodes for measuring the power of the light intensity of the respective beams. The directly measured power from the beams is then used to move a piezoelectric transducer to maintain constant pathlengths for the gyroscope.

Abstract: A beam combiner assembly for a ring laser gyroscope is fabricated by positioning two diffraction gratings, mounted onto respective light transmissive substrates, with respect to the output mirror of the gyro block at an offset angle such that an interference fringe pattern is projected onto the photodetector of the ring laser gyroscope. By tilting the diffraction gratings, with respect to the plane of the output mirror, a corrected number of lines per unit length for the diffraction gratings may be effected, thereby providing a beam combiner assembly which is compensated for manufacturing imperfections and other intolerances. Also, the high sensitivity of angular adjustments for the conventional prism beam combiner is overcome.

Abstract: In a precision ring laser gyroscope, to eliminate the effect of an unwanted and unintentional moment generated as a result of a force being applied onto a pathlength controller, a pathlength control assembly is constructed to have optimal hub and diaphragm portions such that the mirror element mounted thereto does not tilt in response to the unintentional moment.

Abstract: A ring laser gyro path length controller has a cup-like fixture which mounts a piezoelectric actuator and is bonded directly to the gyro block. A mirror assembly is concentrically located within the fixture and is independently mounted to the gyro block thereby enabling independent assembly and disassembly of the fixture and the assembly. Diaphragm sections of the assembly are coaxially positioned and connected to a diaphragm section of the fixture so that bidirectional displacement of the assembly may occur and the moment generated by the actuator results in an axial deflection force on the assembly. A strip of material having a high coefficient of expansion is mounted to the piezoelectric actuator to augment the deflection force as temperature increases thereby reducing the power demands of the actuator.

Abstract: Apparatus is disclosed for retaining an electrically fired getter inside a ring laser gyroscope. A groove is formed in a plate, which is hermetically sealed to a hole in the ring laser gyroscope block. The cylindrically shaped getter is placed longitudinally in the groove such that the getter contacts the groove along only two lines. A mousetrap shaped spring preloads the getter against the groove so as to prevent acceleration forces and vibrations from causing pieces of the getter, heater coil or wire to break loose.

Abstract: A pathlength controller is provided for a three-axis, cube-shaped ring laser gyroscope assembly having three four-sided gyroscopes with six mirrors, including three movable mirrors and three fixed mirrors, wherein the controller connects between the three movable mirrors and the three fixed mirrors, and is adapted to change the pathlength of one gyroscope without changing the pathlengths of the other two gyroscopes.

Abstract: A pathlength controller for a ring laser gyroscope with a modulated mirror is disclosed where a voltage bias is applied to the modulation signal to prevent starting the ring laser gyroscope at a point where it operates with two equal longitudinal modes.

Abstract: A resilient serpentine shaped tungsten wire is formed to match a short wire section to hold a ring laser gyroscope getter. The getter-holder assembly is positioned within a stepped oblong bore so that the getter is in firm contact with the bore surface at two points. This prevents resonances of the getter or holder that might otherwise destroy the getter while subjected to vibrations.

Abstract: A monolithic ring laser gyroscope is formed by six mirrors mounted to the respective center of each face in a cube. Bores in the cube interconnect each of the mirrors. Three orthogonal planes are defined within the cube, each of which contains a laser cavity. Accordingly, three orthogonal beam paths exist, each responsive to rotational inputs about three orthogonal axes.

Abstract: This solderless electrical connector for an electrical cable consists of a helical spring and loop joined together to form a ring. The helical spring provides a snug fit on a matching cylindrical post while offering strain relief protection for the electrical cable, which is routed through the helix of the spring.

Abstract: An electromechanically dithered ring laser gyroscope includes a beam combiner utilizing optical fibers instead of conventional optics. This permits a beam measuring photodetector and associated electronics to be positioned outside the gyroscope or its enclosure. The invention further includes a dither compensator using optical fibers thereby replacing sensitive electronic or optical dither compensating components.

Abstract: A torsional hinge is axially mounted within a central bore of a ring laser gyroscope body. The hinge comprises a plurality of angularly spaced wing sections having generally radially extending slits therein for permitting torsional motion of the gyroscope about the hinge. A plurality of spaced arcuate segments bridge a gap between the wing sections and the confronting surface of the bore and are cemented to the surface for securement of the hinge. By properly dimensioning and positioning the subtending contact areas of the hinge within the bore, the effects of thermal expansion of the hinge are minimized thereby inhibiting distortion of the gyroscope body as well as path length changes with temperature.

Abstract: An inertial measurement unit using body dithered ring laser gyroscopes in which the individual ring laser gyroscopes are firmly attached to a common dithered structure and provisions made to cancel the reaction moment from the dithered structure by a passive resonator. The stable element, to which both the dithered structure and the passive resonator are attached with torsion springs, also serves as a non-vibrating foundation for strapped down accelerometers. The resulting structure contains fewer parts, has lower fabricating cost and permits a smaller package size than a conventional inertial measurement unit with individually body dithered ring laser gyroscopes.

Abstract: A ring laser gyroscope has at least two of its mirrors vibrated perpendicular to their reflective surfaces by equal and opposite amounts to maintain the total beam path length constant. The amplitude of vibration causes the beams to be shifted across surfaces of all of the mirrors by a distance that is at least close to a Bessel zero distance so as to reduce the intensity of back scattered radiation at the main wavelength to a value close to zero. For an equilateral triangular ring laser gyroscope, two of the mirrors are vibrated between about 0.66.lambda. and 0.74.lambda., optimally about 0.71.lambda.. For an isosceles triangle having vibrating mirrors at two vertexes having angles of about 51.65.degree., the magnitude of vibration should be about 0.91.lambda..

Abstract: An equilateral triangular ring laser gyroscope contains drivers to vibrate two of the mirrors synchronously and oppositely along paths displaced by about 4.27.degree. from the bisector of the vertex angles at which those mirrors are located. The magnitude of displacement is about 0.761 .lambda., where .lambda. is the wavelength of laser radiation. The purpose of the vibration is to reduce the lock-in effect in the ring laser gyroscope.

Abstract: A piezoelectric pick-off transducer is used for sensing dither velocity in a ring laser gyroscope. The pick-off transducer is mounted on a spoke connecting the hub and rim of the gyroscope and it comprises two spaced electrodes equidistant about the point of inflection of the spoke. A differential amplifier is connected at its input to the electrodes for generating a signal proportional to dither velocity.

Abstract: Bias shift caused by distortion of a ring laser gyroscope block is corrected by bending the block. Electromechanical bending devices may be piezoelectric crystals adherently attached to the block and resposive to voltage derived from distorting influences.