Abstract

Low-frequency vibration is a harmful factor that affects the accuracy of micro/nano-measuring machines. Low-frequency vibration cannot be completely eliminated by passive control methods, such as the use of air-floating platforms. Therefore, low-frequency vibrations must be measured before being actively suppressed. In this study, the design of a low-cost high-sensitivity optical accelerometer is proposed. This optical accelerometer mainly comprises three components: a seismic mass, a leaf spring, and a sensing component based on a four-quadrant photodetector (QPD). When a vibration is detected, the seismic mass moves up and down due to the effect of inertia, and the leaf spring exhibits a corresponding elastic deformation, which is amplified by using an optical lever and measured by the QPD. Then, the acceleration can be calculated. The resonant frequencies and elastic coefficients of various seismic structures are simulated 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 1.74 V (m·s−2)−1, the measurement range of the accelerometer is 0.003–7.29 m·s−2, and the operating frequencies range of 0.4–12 Hz. The standard deviation from ten measurements is under 7.9 × 10−4 m·s−2. The efficacy of the optical accelerometer in measuring low-frequency, low-amplitude dynamic responses is verified.

Highlights

  • In ultra-precision measurement, ultra-precision machining, metrological verification and similar applications, the low-frequency micro-vibration caused by human activity and natural factors has great influence

  • The accelerometer used in measuring environmental vibration must be designed for low frequency and high sensitivity

  • We used a sine is 50 μm, the resolution is 0.72 nm, and the maximum nonlinearity error is less than 1%

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Summary

Introduction

In ultra-precision measurement, ultra-precision machining, metrological verification and similar applications, the low-frequency micro-vibration caused by human activity and natural factors has great influence. Its amplitude is extremely small (in the micron range) and it cannot be eliminated completely by passive control methods, such as the use of air-floating platforms. A vibration control technique is a good solution. The main problems of active vibration isolation techniques involve the design of appropriate sensor techniques and control schemes. In terms of vibration frequency, the vibration generated by certain human activities, transportation, and mechanical devices ranges of 1–10 Hz [1,2]. The accelerometer used in measuring environmental vibration must be designed for low frequency and high sensitivity

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