Showing papers by "S. M. Aston published in 2004"
TL;DR: In this paper, a hydraulic external pre-isolator for low frequency alignment and control, a two-stage active isolation platform designed to give a factor of ~1000 attenuation at 10 Hz, and a multiple pendulum suspension system that provides passive isolation above a few hertz.
Abstract: To meet the overall isolation and alignment requirements for the optics in Advanced LIGO, the planned upgrade to LIGO, the US laser interferometric gravitational wave observatory, we are developing three sub-systems: a hydraulic external pre-isolator for low frequency alignment and control, a two-stage active isolation platform designed to give a factor of ~1000 attenuation at 10 Hz, and a multiple pendulum suspension system that provides passive isolation above a few hertz. The hydraulic stage uses laminar-flow quiet hydraulic actuators with millimeter range, and provides isolation and alignment for the optics payload below 10 Hz, including correction for measured Earth tides and the microseism. This stage supports the in-vacuum two-stage active isolation platform, which reduces vibration using force feedback from inertial sensor signals in six degrees of freedom. The platform provides a quiet, controlled structure to mount the suspension system. This latter system has been developed from the triple pendulum suspension used in GEO 600, the German/UK gravitational wave detector. To meet the more stringent noise levels required in Advanced LIGO, the baseline design for the most sensitive optics calls for a quadruple pendulum, whose final stage consists of a 40 kg sapphire mirror suspended on fused silica ribbons to reduce suspension thermal noise.
44 citations
TL;DR: In this article, a polarisation based homodyne interferometer that demonstrates a promising sensitivity of approximately 1.3 u 10 ǫ 12 m /Hz 1 /2 is discussed.
Abstract: We discuss a polarisation based homodyne interferometer that demonstrates a promising sensitivity of approximately. This performance figure is limited above 10 Hz by the resolution of the current analogue-to-digitalconverter (ADC). Sensitivity below 10 Hz is influenced by environmental factors a nd / or noise inherent in the laser. Wethen describe the development of a compact interferometric sensor, undertaken at The University of Birmingham,discussing its application as a zero-stiffness sensor for drag-free satellites and suggest a geometry of electrostatic actuator also with zero-stiffness.3 u 10 12 m /Hz 1 / 2 Keywords: capacitive sensing, drag-free, homodyne, interferometer, laser-diode, VCSEL, zero-stiffness 1. INTRODUCTION The development of drag-free technology is central to the exploitation of space as an environment for missions in Fundamental Physics. Missions such as Gravity Probe B 1 , LISA 2 and STEP 3 are key space missions that exploit drag-free technology to achieve their scientific goals. The performance criteria required for the sensor in a drag-free systemhas been considered in previous articles
3 citations