Ring laser gyroscope

About: Ring laser gyroscope is a research topic. Over the lifetime, 2070 publications have been published within this topic receiving 18609 citations. The topic is also known as: Sagnac interferometer.

Ring laser gyroscope having a constant output beat-frequency

Abstract: A ring laser gyroscope having counter-rotating beams rotating around a closed path. A laser gain section is provided for generating the counter-rotating beams. A means for generating and applying a magnetic field to a Faraday substance which substance is located within the optical path of the counter-rotating beams provides a selected bias to the optical beams. Means for combining and detecting a portion of the counter-rotating beams outside of the closed path yields a first signal which contains inertial rotation rate and Faraday bias information. Means for detecting selected components of the laser beams outside of the closed path yields a second signal that contains Faraday bias information but does not contain rotation rate information. A servo means responsive to the first electrical signal generates a control signal which signal is applied to the means for generating a magnetic field to create an operating condition that is held constant to thereby eliminate scale factor nonlinearities and stray field errors in the detected gyroscope rates. A means for correcting the frequency of the first signal by an amount determined by the frequency of the second signal is provided to yield a rotation rate devoid of Faraday bias or scale factor nonlinearity errors.

Large-scale passive laser gyroscope for earth rotation sensing

Abstract: Earth rotation sensing has many applications in different disciplines such as the monitoring of ground motions, the establishment of UT1, and the testing of the relativistic Lense-Thirring effect on the ground. We report the development of a 1 m×1 m heterolithic passive resonant gyroscope (PRG). By locking a pair of laser beams to adjacent modes of the square ring cavity in the clockwise and counter-clockwise directions, we achieve a rotation resolution of about 2×10−9 rad/s at an integration time of 1000 s. The sensitivity of the PRG for rotations reaches a level of 2×10−9 rad/s/Hz in the 5–100 Hz region, currently limited by the detection noise, residual amplitude modulation, and mechanical instability of the cavity. Our initial results improve the reported rotation sensitivity of the PRGs and indicate that PRGs have a great potential for high-resolution earth rotation sensing.

Dual cavity laser gyro

Abstract: A laser gyro having two cavities which are physically separated so that neither mode volumes have any common parts. Each cavity supports a wave traveling in only one direction either clockwise or counter-clockwise. Other waves, which are normally set up in a ring laser gyro, are prevented by a reversed feedback mirror. The gyro produces two waves whose frequencies are shifted in opposite directions by rotation. Lock-in is not possible. The two frequencies are mixed and the beat frequency is detected by optical heterodyne techniques. The response of this rotation sensor is linear down to zero rotation rate and its accuracy is limited by quantum effects.

Isotropic nonplanar ring laser

Abstract: ISOTROPIC NONPLANAR RING LASER ABSTRACT OF THE DISCLOSURE A nonplanar ring laser for use as a laser gyro includes an even number of at least six reflecting surfaces which are preferably all made from the same coating batch or coating run so that they have substantially the same anisotropy charcteristics. The mirrors are divided into pairs of mirrors, and the mirrors in at least each pair must match in their anisotropic characteristics. Note that the matched mirrors need only be in the laser path but not necessarily adjacent. The nonplanar geometric arrangment of the reflecting surfaces is such that the reflecting plane of incidence of each mirror is at substantially a right angle to the reflecting plane of incidence of at least one of the adjacent mirrors in the laser path. Note that the reflecting plane of incidence of each mirror may optionally be at right angles to the reflecting planes of incidence of both its adjacent mirrors in the laser path. The angles of incidence of the mirrors in each matched pair must be substantially the same. Using this geometry, and at least the mirrors in each matched pair being from a single coating batch having the same anisotropy characteristics, the phase and attenuation shifts which are introduced by imperfect coatings are cancelled in the ring laser cavity. Due to the substantial reduction in phase and attenuation anisotropy this ring laser configuration reduces coupling between the two modes travelling in the same direction when used in a multioschillator laser gyro, and therefore improves gyro performance.

Housing and support assembly for ring laser gyroscope

Abstract: Disclosed is a housing and support plate assembly for use with a dithered ring laser gyroscope which attenuates thermal and structural changes due to a varying environment. A dither mechanism is structurally supported between a housing and a support plate in a manner which serves to attenuate cross-axis movement and input axis tilting of the gyro assembly, and torsional stress.