固定相位振动噪声对绝对重力测量的影响  

Effect of vibration noise with fixed phase on absolute gravimetry applying vibration isolator

作　　者：要佳敏 庄伟[1] 冯金扬[1] 王启宇 赵阳[1] 王少凯[1] 吴书清[1] 李天初[1] Yao Jia-Min;Zhuang Wei;Feng Jin-Yang;Wang Qi-Yu;Zhao Yang;Wang Shao-Kai;Wu Shu-Qing;Li Tian-Chu(National Institute of Metrology,China,Beijing 100029,China)

机构地区：[1]中国计量科学研究院,北京100029

出　　处：《物理学报》2021年第21期401-413,共13页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2018YFF0212401,2016YFF0200206);中国计量科学研究院基本科研业务费(批准号:29-AKY1922-20,AKYZD2002)资助的课题。

摘　　要：绝对重力仪在地球物理等领域有着广泛的应用,其普遍采用激光干涉式或原子干涉式的测量原理.现有的绝对重力仪主要利用垂直隔振系统来减小地面振动对参考镜的影响以提升仪器的测量精密度.但在激光干涉式绝对重力仪中,隔振系统对仪器自振效应等固定相位振动噪声的响应可能引入系统误差,即影响测量准确度;在原子干涉式绝对重力仪中也可能有尚未标定的振动来源通过隔振系统引入系统误差.本文对现有绝对重力仪中使用的4种典型隔振系统进行理论分析及仿真建模,以自振脉冲、地脉动和随机振动这3种典型信号为输入,分析激光干涉式绝对重力仪中隔振系统内参考镜的真实振动及其对重力测值的影响,并通过实验对比评估了其中两种系统在实际重力仪中的性能.结果表明,当仪器运行期间存在自振脉冲等固定相位振动噪声时,隔振系统中参考镜振动引入的系统误差可能达到10μGal (1μGal=1×10^(–8) m/s^(2))及以上.使用性能更好的隔振系统或在实际测量中对该系统误差进行修正,有望进一步提高国产激光干涉式绝对重力仪的测量精度.Absolute gravimeter,an instrument which is applied to laser interferometry or atom interferometry for measuring the gravitational acceleration g(approximately 9.8 m/s^(2)),plays an important role in metrology,geophysics,geological exploration,etc.To achieve a high accuracy of several microGals(μGal,1μGal=1×10^(–8) m/s^(2)),a vertical vibration isolator is widely employed in the absolute gravimeter to protect the reference object(a retro-reflector or a mirror)from being disturbed by ground vibration noises.However,the reference object in vibration isolator may still move due to isolator’s response to the impulse caused by the self-vibration effect in laser-interferometry gravimeter,or the forced vibration of the ferromagnetic component in the isolator under the varying magnetic field of magneto-optical traps(MOTs)in atom-interferometry gravimeter.This vibration of the reference object has a fixed phase relative to the detection of the free-fall of a falling object or atoms,leading an additional systematic error to be introduced into measured g value.In this paper,the physical models of four typical vertical vibration isolators used in the current absolute gravimeters are introduced,i.e.a passive Minus K isolator,a passive Lacoste isolator,a one-stage active isolator,and a double-stage active isolator.The simulation models of these isolators are also created with specific resonance periods.Taking a laser-interferometry gravimeter for example,the responses of these isolators under impulse input are analyzed,proving that the real vibration of the reference object,namely the output of each isolator,has a fixed phase relative to the detection of the fringe signal,which indicates the trajectory of the free-falling object,hence resulting in an additional systematic error.To provide a detailed evaluation,firstly the vibration of the reference object under an impulse,a seismic noise,and a random noise,which represent typical ground vibrations,are obtained by running the simulation.Then the corresponding errors in th

关 键 词：绝对重力仪 垂直隔振系统 自振效应 系统误差 

分 类 号：P223.1[天文地球—大地测量学与测量工程]