发展深地探测技术对于推进地球物理发展有重要意义.基于重力梯度的深地传感技术具备自身独有的优势,可以有效弥补现有主要方法的局限.本文提出了一种基于光纤Sagnac干涉仪的重力梯度测量原理,将重力梯度转化为角加速度并利用光纤角加速度计进行精密传感.本文设计了重力梯度原型样机,并利用ANSYS有限元仿真论证了其可行性与稳定性,在此基础上对光纤重力梯度原型样机进行了长达14天的连续静态测试,得到角加速度测量本底噪声低于3×10-10rad·s-2·Hz-1/2,对应重力梯度测量噪声达0.68 E·Hz-1/2.基于光纤Sagnac干涉仪的重力梯度测量没有对传感单元一致性的要求,无需复杂的环境控制与辅助设备,测试结果展现了其高灵敏度特性以及应用于深地探测的巨大潜力.
It is of great significance to develop deep earth exploration technology for advancing the development of geophysics.Deep earth exploration technology based on gravity gradient has its own unique advantages and can effectively make up for the limitations of existing methods.In this paper,a gravity gradient measurement principle based on fiber-optic Sagnac interferometer is proposed.The gravity gradient is converted into angular acceleration and the fiber-optic angular accelerometer is used for precision sensing.The structure of the prototype is designed,and its feasibility and stability are demonstrated by finite element simulation using ANSYS software.On this basis,the static test of the prototype is carried out continuously for 14 days.The results show that the self-noise of angular acceleration measurement is lower than 3X10-10 rad·s-2·Hz-1/2,and the corresponding contribution for the gravity gradient measurement is estimated to 0.68 E·Hz-1 2.The gravity gradient measurement based on fiber-optic Sagnac interferometer has no requirement on the consistency of sensing units and the complex environmental control equipment.The test results show its high sensitivity and great potential for deep earth exploration.