High Precision Inertial Sensors on a One Inch Diameter Optic

Compact, high-precision inertial sensors are needed to isolate many modern physics experiments from disturbances caused by seismic motion. We present a novel inertial sensor whose mechanical oscillator fits on a standard one-inch diameter optic. The oscillators achieve a Quality factor of over 600, 000 and a resonance frequency of 50\, Hz, giving them a suspension thermal noise floor lower than all commercially available inertial sensors. The oscillator is combined with a Pound-Drever-Hall based readout scheme that achieves a displacement noise of 100\, f above 0. 2\, Hz. We integrate the oscillator and readout to make two inertial sensors. Of order ng performance is achieved in a broad band from 0. 1\, Hz to 200\, Hz. Below 20\, Hz, the sensor presented here offers comparable performance to the best inertial sensors available today while being a fraction of the size. Above 20\, Hz, the sensor is, to the author's knowledge, the best demonstrated in the literature to date for a device of this style, with a self-noise floor of 0. 1\, ng. The excellent performance of the sensors across the relevant seismic frequencies, vacuum compatibility, and compact size make it a prime candidate for integration into sophisticated seismic isolation schemes, such as those used by gravitational wave detectors.