A 6D interferometric inertial isolation system

TL;DR

This paper introduces a 6D interferometric inertial isolation system that significantly improves low-frequency inertial motion reduction, enhancing gravitational-wave detector sensitivity through a novel two-stage, closed-loop control scheme.

Contribution

The paper presents a new 6D interferometric sensing-based inertial isolation system with over 100x motion reduction at 100 mHz, advancing low-frequency seismic isolation technology.

Findings

Achieves over two orders of magnitude reduction in inertial motion at 100 mHz.

Enables substantial improvements in gravitational-wave detector sensitivity.

Uses a two-stage, closed-loop control with high gain to transfer low-noise reference mass motion.

Abstract

We present a novel inertial-isolation scheme based on six degree-of-freedom (6D) interferometric sensing of a single reference mass. It is capable of reducing inertial motion by more than two orders of magnitude at 100\,mHz compared with what is achievable with state-of-the-art seismometers. This will enable substantial improvements in the low-frequency sensitivity of gravitational-wave detectors. The scheme is inherently two-stage, the reference mass is softly suspended within the platform to be isolated, which is itself suspended from the ground. The platform is held constant relative to the reference mass and this closed-loop control effectively transfers the low acceleration-noise of the reference mass to the platform. A high loop gain also reduces non-linear couplings and dynamic range requirements in the soft-suspension mechanics and the interferometric sensing.