关键词: 冷原子/
原子干涉仪/
冷原子重力仪/
绝对重力测量
English Abstract
Measurement of absolute gravity based on cold atom gravimeter at large tilt angle
Wu Bin1,Cheng Bing1,
Fu Zhi-Jie2,
Zhu Dong1,
Zhou Yin1,
Weng Kan-Xing1,
Wang Xiao-Long1,
Lin Qiang1
1.Center for Optics and Optoelectronics Research, College of Science, Zhejiang University of Technology, Hangzhou 310023, China;
2.Institute of Optics, Department of Physics, Zhejiang University, Hangzhou 310027, China
Fund Project:Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFC0601602, 2016YFF0200206) and the National Natural Science Foundation of China (Grant Nos. 61727821, 61475139, 61478069, 11604296, 11404286).Received Date:08 June 2018
Accepted Date:20 July 2018
Published Online:05 October 2018
Abstract:The tilt angle of a cold atom gravimeter (CAG) could have a significant influence on the measurement of absolute gravity. The measurement, manipulation, and compensation of the tilt for CAG need to be conducted in order to obtain a high-accuracy absolute gravity measurement. In this paper, firstly, the influences of tilt on absolute gravity measurement under four different conditions are analyzed theoretically by taking into account the position of vacuum system relative to Raman retro-reflection mirror. Then, the experimental investigation is carried out and it is found that the measured results agree well with the theoretical prediction curves. According to the analysis above, we design a scheme for absolute gravity measurement based on two inclinometers, mainly to solve the problem of long-term tilt drift of CAG especially in harsh measurement environment. In this scheme, a high-resolution inclinometer is used to record the tilt angle of Raman retro-reflection mirror, which is fixed on a passive vibration isolation platform. Besides, another inclinometer is utilized to monitor the tilt angle of vacuum chamber of the CAG. By doing so, the vibration noise can be suppressed and the tilt data can be measured with a high precision. Finally, the experimental verification of this proposal is carried out based on our homemade compact cold atom gravimeter, and the high accuracy absolute gravity measurement is realized in a complex workshop environment. Since the vibration noise of Raman mirror is improved by using the vibration isolation platform, the sensitivity of our CAG can reach 319 μGal √Hz. Besides, we measure the long-term changes of gravity with time and find that the experimental results are consistent with the curves calculated by theoretical tidal model. Moreover, due to the precise measurement and compensation for the tilt drift, the accuracy of our CAG is estimated at 12.3 μGal. In order to evaluate this system accuracy, a comparison between our CAG and the FG5 at the same measured site is made. The absolute gravity values determined by both gravimeters coincide with each other. In this paper, we provide a feasible scheme for measuring the absolute gravity in the complex environment. The experimental demonstration of this measurement scheme is performed thereby acquiring some valuable reference data for the practical use of CAG.
Keywords: cold atom/
atom interferometer/
cold atom gravimeter/
absolute gravity measurement
