Rockwell International Corporation

Frederick Aronowitz

Frederick Vescial

Francis M Erdmann

Thomas M Wirt

Kenneth L Steele

Ludd A Trozpek

William T Schmars

An RLG OPTICAL NOISE INJECTOR places a random signal on a PZT driving one mirror controlling the optical path length (OPL) of a ring laser gyro (RLG) and the negative of the signal on a PZT driving a second mirror controlling the OPL. The OPL is therefore maintained constant while injecting random noise into the phase of the counterpropagating beams to avoid dynamic lock-in. Static lock-in may also be avoided by superposing an oscillatory signal on the random signal fed to the first PZT and the negative of the oscillatory signal on the random signal fed to the second PZT.

RLG optical noise injector

Extended laser life may be obtained by measuring, with an ammeter AM, the discharge current applied to a laser (either linear or a ring laser gyro RLG), measuring the intensity of the resulting light beam with an intensity monitor IM, calculating the noise with an integrated circuit IC, and maintaining the discharge current at the lowest level possible which is consistent both with maintaining the intensity above the intensity service limit and the noise below the noise service limit.

Extended laser life

An alignment and path length control apparatus having a mirror housing having a base and a closed wall. The base has a mirrored external surface. The closed wall has a central axis. The closed wall is joined to the base at a base end of the closed wall by a flexible web. The closed wall extends above the base and terminates at a rim defining an aperture. The base has a central region coupled to the cylindrical wall. A post extends from the central region of the base within the cylindrical wall to a top end. A mirror axis extends from the mirrored external surface through the post. The central axis is substantially parallel to the mirror axis. An alignment transducer responds to a first alignment control signal by applying at least a first force between the post and the wall to deflect the mirror axis with respect to the central axis. A linear transducer responds to a linear displacement control signal by applying an axial force to the post to displace the central region longitudinally along the central axis.

Interferometer alignment control apparatus

In-flight scale factor calibration of a ring laser gyro is encumbered by the dependence of scale factor on light beam intensity and by the susceptibility of the intensity monitor to decalibration. The monitor may be calibrated in flight by modulating the mirror alignment, the laser current, or both to modulate the intensity. The intensity modulation produces a modulation of the scale factor. The ratio of the amplitude of scale factor modulation to the amplitude of the measured intensity modulation should be the same in-flight as during factory calibration. If it is not, the intensity monitor is calibrated by multiplying its output by the change in the ratio, and the calibrated intensity measurement rather than the raw intensity measurement is used to determine the scale factor.

In-flight scale factor calibration of ring laser gyro systems

A laser accelerometer comprises a frame having three orthogonal input axes and multiple proof masses, each proof mass having a predetermined blanking surface. A flexible beam supports each proof mass. The flexible beam permits movement of the proof mass on the input axis. A laser light source provides a light ray. The laser source is characterized to have a transverse field characteristic having a central null intensity region. A mirror transmits a ray of light to a detector. The detector is positioned to be centered to the light ray and responds to the transmitted light ray intensity to provide an intensity signal. The intensity signal is characterized to have a magnitude related to the intensity of the transmitted light ray. The proof mass blanking surface is centrally positioned within and normal to the light ray null intensity region to provide increased blanking of the light ray in response to transverse movement of the mass on the input axis. The proof mass deflects the flexible beam and moves the blanking surface in a direction transverse to the light ray to partially blank the light beam in response to acceleration in the direction of the input axis. A control responds to the intensity signal to apply a restoring force to restore the proof mass to a central position and provides an output signal proportional to the restoring force.

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Laguna Niguel, CA, United States of America

Frederick Aronowitz