PRECISION ACCELEROMETERS FOR GRAVITY GRADIENT MEASUREMENTS

An accelerometer, based on a microwave sapphire resonator, is under de velopment for application in a compact gravity gradiometer. This gravi ty gradiometer potentially can be used in space gradiometry, precision navigation, and geodesy. The principle of operation of the accelerome ter is based on measurements of classical spring-proof-mass displaceme nts, which are converted to phase shifts in the output signal of a sap phire microwave resonator transducer. A prototype accelerometer has de monstrated a figure of merit sensitivity [Q(df/dx)] of 3.9 x 10(2) MHz /mum. With a proof mass of 4500 g and a cantilevered beryllium-copper spring having a spring constant of about 60,000 N/m, this result corre sponds to the detection of micro-g accelerations for low-frequency (<1 Hz) components of the acceleration vector by means of a precision fre quency reference source.