| Project/Area Number |
07640562
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体地球物理学
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| Research Institution | National Astronomical Observatory |
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Principal Investigator |
HANADA Hideo National Astronomical Observatory, Division of Earth Rotation, Research Associate, 地球回転研究系, 助手 (60132677)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1996: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | Gravitational Acceleration / Free Fall / Fabry-Perot Interferometer / Corner Reflector / Beam Splitter / Piezoelectric Ceramics / 無人観測 / 惑星重力 / コーナーリフレクタ |
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| Research Abstract |
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.
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