Sensitivity improvement of micro-grating accelerometer based on differential detection method.

A differential detection method (DDM) with a utility type and ease of realization for a micro-grating accelerometer is reported so as to reduce the common-mode noise and improve the sensitivity of the micro-grating accelerometer. The theoretical model is established, based on scalar diffraction theory for differential detection. According to the simulation and analysis of the DDM, the theoretical result shows that the sensitivity of the micro-grating accelerometer can be improved by at least a factor of 2. Based on the analysis, the detection circuit is designed with proper parameters and devices for the handheld experimental prototype, which is realized with our micro-grating acceleration sensor fabricated by inductively coupled plasma, lift-off, and anodic bonding of glass/silicon, etc. The prototype experiment is conducted with the turntable. Compared with the single-order detection method whose sensitivities are 6.797 V/g (zeroth order, 1 g=9.8 m/s²) and 7.767 V/g (first-order), the result of the DDM shows that the sensitivity of the micro-grating accelerometer is 18.61 V/g with an improvement of over two times. The overall signal-to-noise ratio improvement is 6.47 dB with the input of 0.86 g.