Design of optical accelerometer using four-quadrant photodetector

Low-frequency vibration is a harmful factor that affects the accuracy of precision machining and high precision measurement. Low-frequency micro-vibration cannot be completely eliminated by air-floating platforms. Therefore, low-frequency vibration must be measured with high-precision before being suppressed actively. A low-cost high-sensitivity low-frequency optical accelerometer is proposed. This optical accelerometer mainly consists of three components: a seismic mass, a leaf spring, and a displacement sensor (four-quadrant photodetector). When vibration is detected, the seismic mass moves up and down due to the effect of inertia, which is amplified by using an optical lever and measured by the four-quadrant photodetector. Then, the acceleration can be calculated. The resonant frequencies and elastic coefficients of various seismic structures are simulated by ANSYS software to attain the optimal detection of low-frequency low-amplitude vibration. The accelerometer is calibrated using a homemade vibration calibration system, and the calibration experimental results demonstrate that the sensitivity of the optical accelerometer is 4.92 V (m.s(-2))(-1), the measurement range of the accelerometer is 0.0095-2.58 m.s(-2), and the operating frequencies range from 5 Hz to 15 Hz. The efficacy of the optical accelerometer in measuring low-frequency and low-amplitude dynamic responses is verified.