带有力反馈控制的三明治式微机械干涉加速度计

Micromachined Sandwich Interferometric Accelerometer with Force Feedback Control

设计了一种静电力反馈控制的三明治式微机械干涉加速度计,加速度计由敏感芯片、半导体激光器、光电二极管以及相应的驱动电路和反馈控制电路组成.敏感芯片为玻璃-硅-玻璃3层结构,通过硅-玻璃键合体硅工艺制成.硅质量块由铝梁支撑,底部玻璃基片上有金属光栅和电极,通过在质量块和底部玻璃基片上的电极之间施加电压可以调节质量块与玻璃基片间的间隙.入射激光照射到敏感芯片上的光栅上,产生衍射光束,其光强随质量块与下玻璃的间距而变化.反馈控制电路通过测量衍射光强的变化来改变质量块与底电极之间的电压,使得质量块与底部玻璃基片的距离保持为入射光波长1/8的奇数倍,从而提高输出线性度,改善灵敏度,增大量程.

A micromachined sandwich interferometric accelerometer with force feedback control was designed,which consisted of a sensor chip,a laser diode,a photodiode,driving circuit and detecting circuit with force feedback control.The sensor chip was a glass-silicon-glass sandwich structure,and was fabricated using silicon process and silicon glass anodic-bonding and deep etching release process.A proof mass was suspended by aluminium beams attached to the silicon substrate,and a diffraction grating and electrodes resided under the proof mass.The gap between the mass and the bottom glass could be adjusted through electrostatic actuation.A light beam from the laser diode illuminates the grating on the sensor chip,which reflects the incident beam into several diffraction orders.The intensity of these diffraction orders varies with the gap between the mass and the glass.By measuring the variation of the intensity of the 1st diffraction order,the feedback control circuit changes the force feedback voltage between the mass and the glass so that the gap between them was kept to be odd times an eighth of the incident beam wavelength.Therefore,force feedback control can improve the linearity and sensitivity of the output and extend the detection range.