New design of absolute gravimeter for continuous observations

We describe a new absolute gravimeter, which is suitable for long‐term continuous observations. It uses laser interferometry to measure the acceleration of a falling corner cube with reference to atomic standards. Between drops, the corner cube is lifted to the top by rotating the vacuum pipe around a horizontal axis with an angular velocity high enough to keep the cube fixed by centrifugal force. This method has an enormous advantage for making a large number of measurements since there is no complicated mechanism inside the vacuum pipe. This absolute gravimeter seems to have no source of systematic error which will exceed one part in 109 if we can reduce the amplitude of the mechanical vibration to less than about 1.5 nm. We describe here the principle and the results of the experiments that we have made to date.