Initial Demonstration of Fused Silica Dual-Shell Gyroscope Using Indirect Method of Piezoelectric Excitation

Hemispherical resonator gyroscopes (HRGs) fabricated out of fused silica (FS) offer high quality-factor ( $Q$ -factor) properties making the sensors suitable for high-precision gyroscope operation. In this configuration, metal-coating is typically required for electrical conductivity to allow for capacitive actuation and detection of motion. Such method of transduction is relatively simple, but reduces the $Q$ -factor of FS HRGs. To eliminate the metallization and preserve the high $Q$ -factor for FS hemispherical resonator dual-shell gyroscopes (DSGs), an indirect excitation method is designed and demonstrated in this letter. The DSG contains a central stem, an inner device shell as the sensing element, and an outer packaging cap shell. The proposed method utilizes the mechanical coupling between the sensing element and the cap shell. The energy induced by deformation of the cap shell transfers to the inner device shell and excites it at the resonance, thus allowing for gyro operation. In this letter, the method was realized using a lead zirconate titanate (PZT) layer deposited on the cap shell, and the mechanical $Q$ -factor as high as 2.3 million was measured. Using the indirect excitation method, for the first time, gyroscope operation was demonstrated on DSG architectures.