Improved compensation of vibrational noise in the laser interferometer with applications in absolute gravimetry

该项目致力于开发和实现一种创新的概念--振动补偿双臂激光位移干涉仪，以提高绝对重力测量的精度。在这一概念中，第一个通道(绝对重力仪)测量重力和振动加速度的相加组合，第二个通道仅同步测量作用于参考反射器、与加速度计刚性耦合的振动加速度。根据发展起来的绝对重力仪频域分析理论，计算了相应的改正，并对测量结果进行了应用。这一概念在日本东京大学地震研究所的自由落体绝对重力仪实验中得到了验证，在实验中观察到精度提高了100倍。在这一后续项目中，有必要在不同的绝对重力仪上实施项目开发，并使所开发的数据处理算法适应实际测量条件。主要步骤包括开发和修改自适应滤波算法和振动补偿系统，开发对称升降绝对重力仪的数字条纹信号处理方法，以及德国汉诺威莱布尼茨大学大地测量研究所、意大利计量研究所和日本地震研究所改进后的仪器的计量特性。绝对重力测量精度的提高将对地球物理学、火山学、大地测量学、惯性导航和基本计量学产生重大影响。

The project is devoted to the development and realization of an innovative concept of the vibration-compensated two-arm laser displacement interferometer in order to improve accuracy of absolute gravimetry. Within this concept the first channel (an absolute gravimeter) measures an additive combination of gravitational and vibrational accelerations, and the second one synchronously measures only vibrational accelerations, acting on the reference reflector, rigidly coupled with an accelerometer. Based on the developed theory of frequency-domain analysis of an absolute gravimeter, the relevant correction is computed and applied to the measurement result. The concept was proven during experiments with the free-fall absolute gravimeter of the Earthquake Research Institute of the University of Tokyo in Japan, where improvement of precision by factor 100 was observed. Within this continued project it is necessary to implement the project developments in different absolute gravimeters and adapt the developed data processing algorithms to actual measurement conditions. The main steps include development and modifications of the self-adaptive filtering algorithms and vibration compensation systems, development of digital fringe signal processing methods for symmetrical rise-and-fall absolute gravimeters and metrological characterization of the improved instruments at the Institute for Geodesy at the Leibniz University of Hanover (LUH) in Germany, Institute for Metrological Research (INRIM) in Italy and Earthquake Research Institute in Japan. The improved accuracy of absolute gravity measurements will have strong impacts on geophysics, volcanology, geodesy, inertial navigation and fundamental metrology.