Advanced LIGO Two-Stage Twelve-Axis Vibration Isolation and Positioning Platform. Part 1: Design and Production Overview

TL;DR

This paper details the design and production of a sophisticated two-stage vibration isolation platform for Advanced LIGO, combining active and passive methods to achieve unprecedented vibration suppression in a vacuum environment.

Contribution

It introduces a novel multi-stage, imbricated vibration isolation platform with advanced sensors and control systems tailored for gravitational wave detectors.

Findings

Achieves platform motion below 10^(-12) m/Hz^(0.5) at 10 Hz

Combines active and passive isolation for broad frequency suppression

Supports construction and testing of multiple units for LIGO

Abstract

New generations of gravity wave detectors require unprecedented levels of vibration isolation. This paper presents the final design of the vibration isolation and positioning platform used in Advanced LIGO to support the interferometers core optics. This five-ton two-and-half-meter wide system operates in ultra-high vacuum. It features two stages of isolation mounted in series. The stages are imbricated to reduce the overall height. Each stage provides isolation in all directions of translation and rotation. The system is instrumented with a unique combination of low noise relative and inertial sensors. The active control provides isolation from 0.1 Hz to 30 Hz. It brings the platform motion down to 10^(-11) m/Hz^(0.5) at 1 Hz. Active and passive isolation combine to bring the platform motion below 10^(-12) m/Hz^(0.5) at 10 Hz. The passive isolation lowers the motion below 10^(-13) m/Hz^(0.5) at 100 Hz. The paper describes how the platform has been engineered not only to meet the isolation requirements, but also to permit the construction, testing, and commissioning process of the fifteen units needed for Advanced LIGO observatories.