The Litton 11 cm triaxial zero-lock gyro

A very compact triaxial instrument is described, which takes full advantage of the inherent low random walk and high scale factor linearity of the zero-lock ring laser gyro configuration that Litton has developed over the last decade. The triax instrument is based on a rhombic dodecahedral geometry, which can accommodate three nonplanar ring light paths having orthogonal sensing axes. Component count can be considerably reduced by a discharge layout using a single cathode and two anodes to run all three axes with balanced plasma currents. In addition Litton has used its advanced mirror coating technology to develop antireflection coatings at high incidence angles, which have very low loss. This allows us to use a 'reversed' mirror substrate as a Faraday rotator with external magnets, so greatly simplifying the fabrication of a triax device. The resulting instrument is very well suited for the next generation of pointing and tracking applications with a combination of size, random walk, scale factor, resolution and bandwidth requirements beyond the capabilities of any other current technologies.