Developments toward monolithic suspensions for advanced gravitational wave detectors alastair heptonstall, caroline cantley, david crooks, alan cumming

The proposed upgrades to both the LIGO and Virgo gravitational wave observatories will seek to improve detector sensitivity by reducing thermal noise. Based on technologies first implemented at the GEO600 detector, the test mass mirrors will be suspended using fused silica fibres of either circular or rectangular cross section to form monolithic suspensions. In GEO600 cylindrical fused silica fibres were produced using a hydrogen-oxygen flame based machine. Here we report on a new CO2 laser based fibre pulling system under development in Glasgow designed to achieve higher tolerances and reduce contamination of fibres. Preliminary testing of a laser welding process suitable for constructing full scale monolithic suspensions for advanced detectors is described. © 2008 World Scientific Publishing Co. Pte. Ltd.