Interferometer utilizing free masses as a device for measuring gravitational gradients

A Fabn-Perot-Michelson optical interferometer utilizing suspended mirrors i s considered as a device for measuring low-frequency variations of the Eart h's gravitational field. The operating principles of the instrument, the sy stem for maintaining the angular alignment of the mirrors at the operating point, and a simplified model of the gravitational field are all described. The variations of the field tit the location of the interferometer are mod eled numerically and estimates are given of the magnitudes of the measurabl e effects. The results are used as a basis for modeling the operation of th e instrument as a whole.