Nulling and measuring system

摘要

A gravity meter includes a support framework which supports a suspension system having a weight beam to which a reaction mass is attached. The reaction mass includes a dielectric mass which extends partially within first and second cavities formed between respective first and second pairs of conductors. Changes in either the ambient gravitational field or the electric potential on the conductors causes the dielectric mass to move into the first cavity between the first pair of conductors and out of the second cavity between the second pair of conductors or vice-versa, with the force on the dielectric mass being linearly proportional to the voltage between the conductors. An optical detector system determines the position of the weight beam, thus the position of the dielectric mass, and is connected to the voltage source for the plates so that, by adjusting the electric potential between the plates, the weight beam can be moved to a nulled position. Subsequent changes in the ambient gravitational field caused either by movement of the meter or by a change in the ambient gravitational field over time will cause the reaction mass to move and cause the dielectric to move between the respective pairs of conductors. Thus, the required change in the electric potential necessary to renull the system allows remote calculation of the change in the gravitational field.