A coefficient searching based vibration correction method br

Absolute gravimeter has played an important role in geophysics, metrology, geological exploration, etc. It isan instrument applying laser interferometry or atom interferometry to the measurement of gravitationalacceleration g (approximately 9.8 m/s2). To achieve a high accuracy, a vibration correction method is oftenemployed to reduce the influence of the vibration of the reference object (a retro-reflector or a mirror) on themeasurement result of absolute gravimeter. Specifically, in an atomic-interferometry absolute gravimeter, thephase noise caused by the vibration of the reference mirror, namely the vibration phase, can be calculated fromthe output signal of a sensor, either a seismometer or an accelerometer, placed below or next to the mirror.Considering this vibration phase, the fringe signal of the atomic interferometer as a function of the phase shiftset by the control system of the gravimeter can be corrected to approach to an ideal sinusoidal curve, thusreducing the fitting residual. Currently, the parameters in the algorithm of most vibration correction methodsused in atomic-interferometry absolute gravimeters are set to be constant. As a result, the performances of thesemethods may be limited when the practical transfer function between the real vibration of the reference mirrorand the signal of the sensor has a variation due to the change of measurement environments. In this paper,based on a simplified model of the practical transfer function previously proposed in an algorithm used in laser-interferometry absolute gravimeter, a new vibration correction method for atomic-interferometry absolutegravimeter is presented. Firstly, a detailed description of its principle is introduced. With a searching algorithm,the time delay and the proportional element in the simplified model can be obtained from the fringe signal ofthe atomic interferometer and the output of the vibration sensor. In this way, the parameters used to calculatethe vibration phase can be adjusted to approach to their true values in different environments, causing thefitting residual of the corrected fringe to decrease as much as possible. Then the measurement results of thehomemade NIM-AGRb-1 atomic-interferometry absolute gravimeters using this method is analyzed. It isindicated that with the vibration correction algorithm, the standard deviation of the fitting residual of themeasured fringe signal can be reduced by 58% at the best level in a quiet environment. In the future, theperformance of this vibration correction algorithm will be further improved in other atomic-interferometryabsolute gravimeters during their measurements in hostile environments