Tuning Fork Vibratory MEMS Gyroscope with Optical Drive and Sense Modes Detection

We report on the first tuning fork Si micro-gyroscope with optical detection in both drive and sense modes. Our experiments show that compared to the device with capacitive sense detection [1,2], the reported device exhibits lower noise, better bias stability, and shorter warm-up time. The optical transducers used for the drive and sense responses detection, electrostatic transducer for the drive axis actuation, and signal processing electronics are integrated into the same fully functional vacuum-packaged device. The use of optical transducer significantly simplifies fabrication process and overcomes the fabrication limitations and imperfections of the silicon on insulator (SOI) device. The results of the rate-table performance study allowing the achievement of tactical grade performance, including angular random walk (ARW) less than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${0.12}^{0}/\sqrt {hr} $</tex> and in-run bias instability (BI) less than .<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${0.25}^{0}/hr$</tex> Moreover, the device manifests excellent temperature stability of the scale factor and the bias of 680 PPM and, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${1.5}^{0}/hr$</tex> respectively.