Low frequency noise reduction control system for the IMGC-02 absolute gravimeter

A gravimeter is a scientific instrument used to measure Earth’s gravitational acceleration, which is crucial for geophysical studies, mineral exploration, environmental monitoring, and aerospace applications. The primary objective of this research is to reduce the residual noise that affect the measurement of gravitational acceleration within the IMGC-02 gravimeter. To achieve this, we have implemented a dual control system designed to mitigate low-frequency residual noise on the quasi-inertial system, realized with a modified seismometer, that affect measurement accuracy. The first component developed is a passive control system, besed on a customized hydraulic suspension, to dampen vibrations. This system is engineered to absorb and dissipate kinetic energy, thereby reducing the transmission of low-frequency vibrations to the reference mirror of the interferometer. The second component is an active control system, which employs a magnetic force generated by a voicecoil integrated in the modified sismometer. This system dynamically counteracts residual vibrations by producing controlled magnetic forces that oppose to the detected movements. Our experimental results demonstrate a significant reduction in measurement noise, enhancing the accuracy of gravitational acceleration measurments. The combined passive and active control systems exhibit superior performance in isolating the system from low-frequency disturbances compared to the original configuration. The findings from this research provide valuable insights into low frequency vibration isolation techniques plus commercially avaible and contribute to the development of enhanced gravimetric measurement instruments. This dual approach could be further refined and applied to other precision measurement systems where vibration isolation is critical.