Observation and analysis of the quality factor variation behavior in a monolithic fused silica cylindrical resonator

Cylindrical resonators are commonly used in Coriolis vibratory gyroscopes (CVGs), which measure angular velocity through the precession of solid waves. Quality factor and its homogeneity are critical indicators of the resonator. In this paper, we present the observation and analysis of the Q factor variation behavior around the resonator's axis of symmetry. We measured the resonator's Q factor by the amplitude frequency response (AFR), with an acoustic source for excitation and a laser Doppler vibrometer (LDV) for detection. We then theoretically analyzed the Q variation behavior based on the two-dimensional mass-spring model. The experimental results were consistent with the theoretical calculation. By comparing experimental results with numerical calculations, we showed that the nature of this Q variation was due to the fact that when the excitation direction is misaligned with principle axes, for each detection point, the vibration is the superposition of two eigen-modes, and fitting with a one-dimensional oscillator would result in repetitive errors. This work is significant for understanding the mechanism of resonator's Q factor variation behavior, as well as improving CVG's performances.