The Singer Company

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Kearfott Guidance & Navigation Corporation

John C Stiles

Bo H Ljung

Lincoln S Ferriss

Hubert F Elbert

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.

Beam combiner assembly for ring laser gyroscope

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.

Ring laser gyroscope getter-holder

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.

Monolithic three axis ring laser gyroscope

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..

Ring laser gyroscope with doppler mirrors

In a ring laser gyroscope having a triangular optical resonator with mirrors at its corners, in order to prevent lock-in, a portion of the light from the beams that passes through the mirrors at the corners is fed back into the clockwise and counter-clockwise beams after being passed through an optical resonator containing a nonreciprocal phase shifter.

Nonreciprocal phase shifter for a ring laser gyro

An instrument which performs with precision either as a pickoff or torquer and which is not subject to geometrical errors due to the electrodes going out of round. The pickoff electrodes of the instrument are mounted adjacent the end of the movable element instead of being concentric to it. Because of the location of the pickoff electrodes relative to the movable element, the device is a variable area pickoff rather than a variable gap pickoff. This provides the advantages of obtaining outputs from the X and Y axes which are a linear function of the motion of the movable element and, therefore, the displacement angle, as determined by the ratio of X and Y outputs, is independent of the amplitude of motion.

Electrostatic pickoff and torquer

A two-axis rate gyroscope of the captured type is provided having a cylindrical rotor with one or more inwardly projecting flanges. The rotor is disposed within a sealed toroidal cavity in a rotor housing and the interior of the cavity is evacuated to a 'hard' vacuum. An electrostatic suspension system restrains the rotor from translatory movement along the gyroscope spin axis and two axes perpendicular thereto so that a virtually frictionless spin bearing is provided for the rotor. The suspension system functions to prevent relative angular rotation between the rotor and the rotor housing about two precession axes. The rotor housing is mounted on a flexure joint which prevents translatory movement of the housing along three orthogonal axes but permits rotational movement of the housing about the two precession axes. Vibrating beam force transducer means exert a reaction force on the housing which prevents rotation of the housing about the two precession axes in response to input rates applied to the gyroscope, so that the electrical output signals of the transducer means are a function of the input rates applied to the gyroscope. The rotor housing, flexure joint, rotor and vibrating beam force transducers are disposed within a sealed casing which may be evacuated separately from the toroidal cavity within the rotor housing, so that the toroidal cavity may be easily evacuated to the higher degree of vacuum required for a frictionless rotor spin bearing. The cylindrical rotor structure permits the use of a simplified electrostatic suspension system in which the suspension electrodes also function as rotor displacement sensing electrodes.

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Morris Plains, NJ, United States of America

John C Stiles