Proceedings Article | 9 January 2023
KEYWORDS: Resonators, Polishing, Optical spheres, Wet etching, Silica, Surface roughness, Surface finishing, Gyroscopes, Etching, Scanning electron microscopy
Hemispherical resonator gyro is a novel type of high-precision and high reliability inertial grade solid gyro. In addition to have the features of simple structure, reduction in the number of parts, small volume, light-weight, stable performance, strong anti-interference ability, no need of temperature compensation, which makes it widely used in inertial system. The hemispherical resonator is the core component of high-precision hemispherical resonator gyro. The effect factors affecting the precision of hemispherical resonator gyro are roundness, concentricity, roughness, quality factor (Q factor) and frequency splitting after the hemispherical resonator is machined. The processing method and strictly process control determine the precision and Q factor of the hemispherical resonator. The loss of hemispherical resonator is discussed. The mechanical loss factors of hemispherical resonator include surface loss, thermal elastic loss, anchor loss and internal friction loss. The limiting factors of hemispherical resonator Q factor are surface quality, processing stress and geometrical structure. The structure of hemispherical resonator is designed using Corning 7979 fused silica as material. The designed surface roughness should be less than 0.02μm, the roundness and concentricity should be less than 0.3μm. Comprehensively considering theoretical precision and engineering application, we proposed a set of precision machining technology, including precision machining, precision polishing, and chemical etching. Using such technology, the roundness of resonator sphere is 0.17μm, the surface roughness of resonator sphere is 15.2nm, Q factor is 3.11× 107 .
