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

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