Effect of diaphragm perforation on quality factor of hemispherical resonator gyroscope

In this work, thermoelastic damping (TED) effect of diaphragm perforation on a hemispherical resonator is investigated, and is experimentally shown to improve the quality factor of the resonator. Specifically, this paper reports the quality factor improvement of a very high Q hemispherical resonator gyroscope (HRG) through making a hole on the micromachined HRG´s shell. A hole (200μm in diameter) at the apex of a hemispherical shell (600μm in diameter) increases the Q and thereby ring down time by more than 50% and 100% experimentally and theoretically, respectively, for the HRG at an n=2 resonant frequency of 170kHz. Adding such a hole increases the resonant frequency only a few percent.