用于绝对重力仪的落体旋转评估方法

Evaluation Method of Falling Object Rotation for Absolute Gravimeter

介绍了一种自主搭建的测量落体在自由下落过程中旋转角速度的装置,评估了不同落体旋转角速度引入的旋转误差对重力测量的影响。针对具有旋转初速度的落体在真空腔内自由下落的运动模型,该装置采用光杠杆原理,将高精度位置传感器(PSD)作为光跟踪设备,研究并推导出落体由旋转所导致的反射光位移与下落时间的关系。然后,对PSD采集记录的时间位移曲线进行拟合,求解落体单次下落的旋转角速度值。在调整真空腔垂直度后,最大旋转角速度值可减小为16.88 mrad/s,引入的重力测值不确定度为0.57μGal,即该状态下落体的释放更加平稳。实验表明,该装置不仅可以进一步提升绝对重力仪中落体传动机构的装调精度,还可以对光学干涉绝对重力仪工作过程中的落体姿态进行监测,进一步降低落体旋转所引入的测量不确定度。

A self-built device for measuring the angular velocity of falling object in the process of free falling is introduced,and the influence of rotation error caused by different angular velocities of falling object on gravity measurement is evaluated.Aiming at the free-falling motion model of a falling object with an initial rotation speed in a vacuum cavity,the device adopts the principle of optical lever and uses a high-precision position sensitive detector(PSD)as a light tracking device to study and deduce the relationship between the reflected light displacement caused by rotation and the falling time.Then,the time displacement curve recorded by PSD is fitted to solve the rotation angular velocity of the single fall of the falling object.After adjusting the verticality of the vacuum cavity,the maximum rotational angular velocity value can be reduced to 16.88 mrad/s,the introduced gravity measurement uncertainty is 0.57μGal,indicating that the falling object is released more stably at this state.The experimental results show that the device can not only further improve the installation and adjustment accuracy of the falling object transmission structure in the absolute gravimeter,but also monitor the attitude of the falling object in the working process of the optical interference absolute gravimeter,and further reduce the measurement uncertainty introduced by the falling object rotation.