Gradiometer determining gravity variations - has laser beam and modulator generating frequency difference between beam circular polarisation (NL 4.12.79)

摘要

The gradiometer has a laser (2) whose beam (3) has several circular polarisations, and a modulator (12) with a photoelastic element in the laser beam (3) path for differential changes of circular polarisations as a function of a load. The modulator (12) centre is stationary relative to the beam (3) path. Two mass dipoles (16, 18) perpendicular to each other are connected to the modulator (12) ends, so that a gravity gradient in a plane perpendicular to the beam (3) path generates torques in the above mass dipoles (16, 18), and thus a frequency different between the circular polaridation. This frequency difference is measured by a device (30).