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.

Rotation scheme for single-axis indexing RLG INS

Abstract: At present,the conventional 4-position rotation-stop scheme is widely utilized in single-axis indexing RLG INS.However,its error propagation analysis shows that this 4-position rotation-stop scheme cannot completely remove the constant drifts of the gyros which are assembled in the plane perpendicular to the rotation axis,and the heading changes of the carrier body may also deteriorate the compensation effects.This paper proposes an improved 4-position rotation-stop scheme,which can remove all the constant drifts of the gyros assembled in the plane perpendicular to the rotation axis.Based on this,a 4-position rotation scheme with dynamic stop time is proposed,which can remove the influences of the body heading changes to the compensation effects.The analysis results indicate that these proposed measures and approaches,which could guarantee the system reliability and improve the system accuracy,can be easily implemented and applied in the real single-axis indexing INS.

Azimuth Determination Using a Low Noise Ring Laser Gyro Inertial Measurement Unit.

Abstract: : The performance requirements for a ring laser gyro inertial measurement system to achieve sub-arc second azimuth determination capability have been developed. Parallel theoretical studies link these requirements to identifiable laser gyro design parameters and indicate that a feasible design could be implemented within practical constraints. A feasibility system is being assembled which will consist of 3 Raytheon RB-25 multioscillator gyros and 3 Bell Aerospace Model XI accelerometers. The instrument cluster will be mounted on a single-degree-of-freedom rotary fixture. Rotation of the cluster will be used to washout long-term error contributors with a Kalman filter using a pseduo-velocity measurement technique.

System, circuit and method for off-mode-peak operation of ring laser gyroscopes

Abstract: A system, circuit and method are disclosed for operating a Ring Laser Gyroscope (RLG) off-mode-peak to avoid exciting undesirable transverse modes. An alternate PLC operating point can be used to bias the optical path length of the RLG to an appropriate side of an ideal integer number of wavelengths, and thus avoid exciting the undesirable transverse modes. Although this alternate PLC operating point is not perfect with respect to establishing an integer number of wavelengths, this operation provides acceptable performance of the RLG's (in particular, short length path RLG's), and acceptable margin can be established relative to variations in the PLC set points involved.

External mirror type gas laser tube

Abstract: PURPOSE:To obtain the titled laser suitable for ring laser gyroscope by a method wherein a discharge outlet is provided in the neighborhood of the center of a laser fine tube, and anodes in the neighborhood of Brewster windows at both ends, respectively; then the discharge outlet is arranged at the center of the cylindrical cathode in a vacuum casing. CONSTITUTION:The anode 5' is buried also in the neighborhood of the Brewster window 3' of the laser fine tube 1, anodes thus being provided in a total of two, and the discharge outlet 2'' is arranged at the center of the anode 6, i.e., nearly at the center of the fine tube. The construction of other parts is almost the same as that of the conventional laser tube. This construction brings gas flows 12 and 12' due to DC discharge which direct to the cathode from the anodes 5 and 5' in symmetry, and therefore the variation in the frequency of a laser beam passing through the laser fine tube is cancelled. Accordingly, in the case of constructing the external mirror type ring laser gyro, a piece of laser tube is sufficient, and the structure and the adjustment of the device are simplified.

Optical combiner for a ring laser gyro

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. It is split into two identical sub-prisms with negligible-thickness beam splitters at the common interface of the sub-prisms. It has a slanted outward end carrying two combining light heterodyne sensors. To reduce the outward extension of the prism from the ring laser gyro another embodiment has the composite prism lying flat on the substrate of the partly transmitting corner mirror. It uses a forty five degree prism surface to turn the laser light through a right angle to deliver the outwardly directed laser beams into a direction parallel to the surface of the mirror substrate.