GRAVITY AND DIFFERENTIAL GRAVITY SENSOR, AND SYSTEM AND METHOD FOR MONITORING RESERVOIRS USING SAME

摘要

A gravity sensor is disclosed which includes a first mass adapted to free fallwhenselectively released from an initial position. The mass has optical elementsadapted tochange a length of an optical path in response to movement of the mass. Thesensoroutput is coupled to a beam splitter. One output of the splitter is coupledsubstantiallyoptically directly to an interferometer. Another output of the splitter iscoupled to theinterferometer through an optical delay line. A frequency of the interferencepattern isdirectly related to gravity at the mass. A second such mass having similaroptics,optically coupled in series to the first mass and adapted to change the pathlength inopposed sign, when selectively dropped to cause time coincident movement ofthe twomasses, generates an interference pattern having frequency related to gravitydifference.