Scanning measurement of surface error and thickness variation of the hemispherical resonator

Hemispherical resonant gyroscopes (HRGs) are solid-state vibration gyroscopes with the highest precision and are widely used in the aerospace field. The core part of the gyroscope is the resonator, which is a thin-walled hemi-spherical shell. Surface error and thickness variation of a hemispherical shell causes frequency splitting, which degrades the performance of the HRG. In order to guide the mass leveling of hemispherical resonator, this paper presents a new method for scanning measurement of the surface error and thickness variation of hemispherical res-onators. First, a multi-axis platform is designed for noncontact sensor scanning measurements along the meridian and latitudinal lines of the hemispherical resonator. Second, the error model of the measurement system is estab-lished. The surface error of the standard sphere is measured to calibrate and compensate for the assembly errors of the measuring device. In addition, the identification accuracy of assembly errors and the influence of assembly errors on thickness measurement are simulated by a computer. Finally, the surface error and thickness variation of the hemispherical resonators are measured. The method is experimentally demonstrated and validated with a wave -front interferometry test. The results show that the method can achieve high precision and high repeatability, which is instructive for assessment of the machining error and further evaluation of the hemispherical resonator. (c) 2022 Optica Publishing Group

Automated summary

In this study, a new method for measuring the surface error and thickness variation of hemispherical resonators is proposed. By designing a multi-axis platform for noncontact sensor scanning measurements, an error model of the measurement system is established, and high precision and high repeatability measurements are achieved through calibration and compensation using a standard sphere.