Patent ID: 8387456

Claim:
A differential gravimeter comprising: a first interferometer, wherein the first interferometer comprises: a first reference arm having a first reference path length that is based on a first gravitational field, wherein the first reference arm conveys a first reference signal; a first sample arm having a first sample path length that is based on a second gravitational field, wherein the first sample arm conveys a first sample signal; a first beam splitter, wherein the first beam splitter distributes the first reference signal into a first signal and a second signal, and wherein the first beam splitter distributes the first sample signal into the first signal and the second signal; a first photodetector, wherein the first photodetector receives the first signal; and a second photodetector, wherein the second photodetector receives the second signal; wherein a change in a difference between the first reference path length and the first sample path length induces a first intensity change in the first signal and a second intensity change in the second signal, and wherein the first intensity change and the second intensity change are equal and opposite; and wherein a change in a difference between the first gravitational field and the second gravitational field induces the first intensity change of the first signal and the second intensity change of the second signal; wherein the gravimeter outputs an output signal representing a differential gravity based on a difference between the first gravitational field and the second gravitational field.