干涉法测量重力加速度
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摘要
利用大学物理教学实验仪器搭建了一个干涉法测量重力加速度的装置.在迈克耳孙干涉仪光路中,将动镜平置于吸入式电磁铁移动杆的顶端.电磁铁线圈通电后移动杆被快速吸回,使动镜自由下落.用示波器记录下落过程中的干涉光强信号,利用局部正弦曲线拟合可得到远小于半波长的位移分辨率.利用二次函数拟合位移-时间曲线,得到重力加速度.根据多次测量10 ms(位移约0.5 mm)的下落数据,得到北京地区重力加速度为9.803±0.003 m/s~2.
A laser interferometer to measure gravitational acceleration is built from low cost college laboratory apparatus. The device is basically a Michelson interferometer,in which the movable mirror is placed horizontally on the flat end of the plunger of an electromagnet. When the electromagnet coil is energized,the plunger will be quickly sucked back,leaving the movable mirror fall freely in air. At the stage of falling,the interference light intensity is recorded by an oscilloscope,and by fitting the signal with local sine waves,position of the movable mirror can be obtained at a precision much higher than the half wavelength of the laser. Finally,gravitational acceleration is extracted from the displacement-time curve of the movable mirror by a quadratic fitting. By using the data of 10 ms falling,which corresponds to displacement about 0. 5 mm,repeatable result of the gravitational acceleration in Beijing is obtained as 9. 803 ± 0. 003 m/s~2.
A laser interferometer to measure gravitational acceleration is built from low cost college laboratory apparatus. The device is basically a Michelson interferometer,in which the movable mirror is placed horizontally on the flat end of the plunger of an electromagnet. When the electromagnet coil is energized,the plunger will be quickly sucked back,leaving the movable mirror fall freely in air. At the stage of falling,the interference light intensity is recorded by an oscilloscope,and by fitting the signal with local sine waves,position of the movable mirror can be obtained at a precision much higher than the half wavelength of the laser. Finally,gravitational acceleration is extracted from the displacement-time curve of the movable mirror by a quadratic fitting. By using the data of 10 ms falling,which corresponds to displacement about 0. 5 mm,repeatable result of the gravitational acceleration in Beijing is obtained as 9. 803 ± 0. 003 m/s~2.
引文
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[2]吴彬,王肖隆,等.冷原子干涉型重力仪的发展现状与趋势[J]导航与控制,2015,14(2):2-9.
[3]冯金扬,李春剑,粟多武,等.绝对重力仪的发展现状及重力计量体系介绍[J].导航与控制,2015,14(2):10-16.
[4]胡华,伍康,申磊,等.新型高精度绝对重力仪[J].物理学报,2012,61(9):542-549
[5]赵凯华.新概念物理教程:光学[M].高等教育出版社,2004.
[6]FENG Jin-yang,WU Shu-qing,LI Chun-jian,et al.Free-fall absolute gravity measurement based on double interferometers[J].Optics and Precision Engineering,2015,23(10):2740-2746.