A high dynamic range MOEMS accelerometer based on multi-order diffraction method

A high dynamic range MOEMS accelerometer based on multi-order diffraction method is presented in this paper. The accelerometer consists of a frequency-stabilized laser source, a diffraction grating, and a mirror attached to a mass block with symmetric cantilever beams, to achieve a few ug resolution. The traditional interferometry only uses the ±1 order diffraction, the accelerometer can obtain high measurement accuracy but the measurement range remains only several mg. This paper introduces a new interferometric method combining ±1 and ±3 order diffraction, and the model of multi-order diffraction measurement is established. The higher order diffraction intensity is proportional to the lower order diffraction intensity, so the higher order diffraction light can be used to improve the dynamic range of the system. And positive and negative order diffraction difference can suppress the common mode noise at the same time. Theoretical analysis and experimental results show that the dynamic range of accelerometer is improved by 9 times under the condition that other conditions remain unchanged.