Suppression of null signals in LiTaO3 crystal fork vibratory gyroscope

A LiTaO₃ tuning fork vibratory gyroscope has a high sensitivity, because of its high electromechanical coupling for the bending f_x mode and its orthogonal f_x mode, and high Q value for driving and adjustable Q value for detecting f_y mode. Our trial LiTaO₃ fork with cuboid arms (7.0 mm long, 1.0 mm wide, 1.0 mm thick, 0.3 mm gap) has a high sensitivity of 0.5 mV/deg/sec for 1 V pp input at 16.5 KHz. But the sensitivity is often reduced by spurious driving and detection modes coupling due to electrostatic coupling, electromechanical coupling and mechanical coupling. We experimentally analyzed the leakage couplings separately and proposed a new configuration of driving and detection electrodes for functional laser trimming. Also we proposed the additional slit formed by laser at an arm-edge of fork to achieve orthogonal vibrations for the f_x mode and the f_y mode. These functional YAG laser trimmings can suppress the leakage coupling or leakage signal voltage to -50 dB of driving voltage