Development of a Measurement Method of Gravitational Acceleration by Using a Fabry-Perot lnterferometer

本文提出了一种利用具有两个后向反射器和两个分束器的法布里-珀罗涉仪进行绝对重力测量的方法，并给出了理论分析和一些实验结果。该方法包括：1)利用压电陶瓷产生的加速度依次抛起下角反射器；2)控制上角反射器的位置，使干涉仪中的光路长度保持恒定；3)测量和分析馈入控制上角反射器的压电陶瓷的信号。在落差小于1 mm的重力加速度作用下，其灵敏度为10^~(-9)。为了获得如此高精度的重力加速度测量，需要具有大透射率的分束器和具有大反射系数的角反射器。用透射率为0.5的分束器进行的实验表明，法布里-珀罗涉仪具有预期的特性。其他实验证实，该压电陶瓷可以连续抛起6 mm以上的角反射器。利用响应速度更快的压电陶瓷将角反射器抛得更高，并控制上角反射器的位置，是今后研究的课题。这种方法适合于无人自动测量重力，例如在行星表面，因为它需要较少的机械运动。

A method of absolute gravity measurement which utillizes a Fabre-Perot interferometer with two retroreflectors and two beam splitters are proposed and theoretical evaluation and some experimental results are shown. The method consists of 1) throwing up the lower corner reflector successively by using an acceleration produced by piezoelectric ceramics, 2) controlling the position of the upper corner reflector in order that the optical path length in the interferometer should be constant, and 3) measuring and analyzing the signal fed to the piezoelectric ceramics which control the upper corner reflector. It has a sensitivity of 10^<-9> in the gravitational acceleration with falling distance of less than only 1mm. Beam splitters with large transmission coefficient and corner reflectors with large reflection coefficient are necessary in order to measure the gravitational acceleration with such a high accuracy. The experiments with a beam splitter of the transmission coefficient of 0.5 showed that the Fabry-Perot interferometer had characteristics as predicted. The other experiments confirmed that the piezoelectric ceramics could throw up the corner reflector continuously by higher than 6 mm. To throw up the corner reflector higher by using the piezoelectric ceramics with faster response and to control the position of the upper corner reflector are the subjects for a future study. This method is suitable for unmanned automatic measurement of gravity such as on the surface of the planets since it requires less mechanical motion.