绝对重力仪落体质心光心调整技术研究

In development of the absolute gravimeter, the optical center of the falling body will rotates around the centre of mass while these two centers are not coincided. This rotation will generate the additional acceleration, which is one of the most important sources of the systematic error. Because of the difficulty of measuring this angular velocity, we can not correct this systematic error from the final measurement results. This project focus on desiginning a adjusting device based on the laser interferometer principle to find the distance between the optical center and the center of the mass of the falling body.And by using the result, the location of the center of the mass can be adjusted until conciding with the optical center at the micron level. And this misalignment can only introduce measurement error less than 1 μGal and finally this adjusting technology, as an Exploratory Research, can be used in improving the accuracy of the absolute gravimeter. And in the same time, this technology can also be used in the industrializationas of the domestic high precision absolute gravimeter as technical reserves.

在绝对重力仪的研制中，落体在自由下落过程中由于角立体棱镜的光心与落体的整体质心不重合会产生光心围绕质心旋转的现象。这种旋转将会产生一个附加的加速度，成为最终测量系统偏差的重要组成部分。由于旋转角速度测量的困难和不确定性，故不能通过估算从最终测量结果中修正消除。本研究通过基于激光干涉原理的落体质心位置检测方法研究，设计一套检测调整装置，测量落体质心相对于光心的距离，并通过调整落体附加质量块调整质心位置，实现落体质心与光心在微米级的重合，使得由此引入的绝对重力测量系统偏差缩小到1微伽以内，为进一步提高自主研发高精度绝对重力仪的测量精度进行探索性研究，并为我国高精度绝对重力仪的产业化提供技术储备。

经典的激光干涉绝对重力仪研究中，核心测量部件是用于敏感地球重力场的落体。由于绝对重力测量的基本原理是基于落体自由下落时落体的光心和参考棱镜的光心之间形成的点干涉图样，而重力场则是直接作用在落体的质心上，因此落体的光心和质心不重和会引入较大的测量误差，一般会达到几十至100微伽量级。本项目基于激光干涉原理，构建一套可以在大气环境下完成落体质心光心重合度检测机构，完成落体光心质心不重合度的测量，通过调整落体上的质心位置精调螺母，将落体的质心与光心重合误差缩小到30um，由此引入的测量误差缩小到1uGal以内，从而完成高精度落体的制造。利用该技术可以科学高效的完成落体的光心质心重合度的检测、调整，从而消除由此引入的绝对重力测量误差，是构建具有自主知识产权的高精度激光干涉绝对重力测量仪器的核心技术之一。