High-Q Navigation-Grade Fused-Silica Micro Birdbath Resonator Gyroscope

Fused silica is an excellent material for micro mechanical and optical devices due to its excellent quality factor (Q). We developed a novel three-dimensional shell resonator architecture called the micro birdbath resonator using a micro blowtorch molding technique to make fused silica shell resonators of different sizes, sidewall curvature profiles, shell thickness profiles and anchor shapes with excellent surface quality. The micro birdbath resonator with a diameter of 5 mm demonstrates a Q of 5.87 million for n=2 wine-glass mode frequency at 9.162 kHz. The micro birdbath resonator with a diameter of 10 mm demonstrates a Q of 8.7 million at 5.897 kHz and a Q of 12.5 million at 12.798 kHz. A vacuum-packaged birdbath resonator gyroscope (BRG) with 5-mm-diameter birdbath resonator demonstrates an angle random walk of 0.0027 deg/√hr and a short-term in-run bias stability of 0.01 deg/hr. The 10-mm BRG demonstrates an angle random walk of 0.00016 deg/√hr and a short-term in-run bias stability of 0.00138 deg/hr. The performance of the BRG is the best among MEMS gyroscopes reported to date.