An Optimized Vibration Correction Method for Absolute Gravimetry

Abstract

Accurate observations of the gravitational acceleration (<inline-formula> <tex-math notation= LaTeX >$g$ </tex-math></inline-formula>, about 9.8 m/s²) provide important geophysical data for use in geophysics, metrology, and geodesy. At present, the most widely used absolute gravimeter determines the value of <inline-formula> <tex-math notation= LaTeX >$g$ </tex-math></inline-formula> by tracking a falling retroreflector in a vacuum using a laser interferometer. The precision and accuracy of the measurement are mainly affected by ground vibration noise. When compared with a vibration isolator, vibration correction offers a simple and convenient way to reduce the influence of ground vibrations. Previous correction methods have used a low-noise seismometer as a detector. However, their performance is limited by the seismometer’s bandwidth (which usually ranges from 0.01 to 60 Hz). An optimized correction method combined with digital filtering is proposed here to increase the seismometer’s bandwidth numerically. Experimental results show that the accuracy and precision of the corrected results using the optimized method are improved in both relatively quiet and complex vibration environments. And better improvement is shown in complex vibration environment. Therefore, both the feasibility and the superiority of the proposed method have been verified. Further improvements can be achieved by using a higher-order digital filter.