Nano-g Optical Accelerometer With a Large Dynamic Range and Low Noise Floor

Optical microelectromechanical system (MEMS) devices are often used to measure vibrations with exceedingly small amplitudes, which are extensively used in acceleration and seismic sensors. However, due to the limitations of the sensing principle and the variation in ambient temperature, the measurement accuracy and dynamic range of these optical devices are relatively general. As a solution, this article presents the design of an electromagnetic feedback optical MEMS accelerometer with temperature control. Two single accelerometer chips form the acceleration sensing structure, assembled via manual microassembly. The electromagnetic feedback control system enables the sensor to operate in the linear range, and the temperature control system maintains a stable operating temperature for the equipment. The novel design of the sensing structure with two sets of control systems enables the accelerometer to have an extremely low noise floor, along with a wide dynamic range. Experimental results confirm that the device can achieve a voltage sensitivity of 2643 V/g and dynamic range values up to 3.9 mg. The self-noise of the sensor is less than 3 ng/ $\surd $ Hz in the frequency range from 0.8 to 7 Hz. The bias stability is 11.9 ng at ${t}$ = 1.8 s. Considering the excellent performance, the proposed device has significant application potential in seismic and gravity measurements.