A high-Q birdbath resonator gyroscope (BRG)

We report a three-dimensional (3-D) micro-scale shell gyroscope made of fused silica (FS), called the birdbath resonator gyroscope (BRG). The BRG operates at 10.45 kHz, far above most environmental noise frequencies, and offers high mechanical quality factor (Q_n=2 = 249 k) and low stiffness and damping anisotropy (Δf_{n = 2} = 14 Hz, Δ1/τ_n=2 = 4.1 mHz). The birdbath (BB) resonator can be fabricated with good structural symmetry because its anchor is self-aligned to the rest of the structure. The BB resonator also has large frequency separation between the n=2 wineglass modes and the closest parasitic mode (|f_parasitic - f_n=2|/f_n=2 = 0.3), which makes the gyro less sensitive to vibration. The BRG is fabricated using a 3-D μ-blow-torching process and assembly on an electrode substrate made with the Silicon-On-Glass (SOG) process. The BRG is operated in the force-rebalance mode at <;1 mTorr vacuum and room temperature, and has a scale factor of 27.9 mV/(deg/sec), a full-scale range >400 deg/sec, an angle random walk (ARW) of 0.106 deg/√hr and a bias stability of 1 deg/hr.