Patent ID: 7305879

Claim:
A cross-component superconducting gravity gradiometer having at least one gradiometer axis, the gravity gradiometer comprising: a pair of substantially identical angular accelerometers at said at least one gradiometer axis, having spring-mass assemblies, mounted on a rigid platform, and having pivot axes thereof aligned each with respect to the other, each spring-mass assembly including a mass defined by a beam integrally joined to a housing by a flexure joint at a center of mass thereof, said flexure joint allowing elastic pivotal displacement about a corresponding pivot axis defined thereby while providing support to resist displacement in other directions, said beam having opposing end portions each being contoured to provide four sensing faces orthogonal to a common plane of said beam; said pair of angular accelerometers being interconnected by a first sensing circuit and a second substantially identical sensing circuit; each of said first and second sensing circuits including, for each angular accelerometer of said pair thereof, a pair of inductive sensing elements positioned in close proximity to a respective sensing face of said mass of said spring-mass assembly of each said angular accelerometer, an inductance of each of said pair of inductive sensing elements being in correspondence with an angular displacement of said mass of each said angular accelerometer; and a Superconducting Quantum Interference Device (SQUID) having an input coil, wherein, in each of said first and second sensing circuits, said pair of inductive sensing elements of each said angular accelerometer is connected in parallel with said input coil of said SQUID, wherein said first sensing circuit is a differential-mode sensing circuit for sensing a gravity gradient, and said second sensing circuit is a common-mode sensing circuit for sensing an angular acceleration.