PROGRESS ON THE MONOLITHIC SUSPENSION FOR ADVANCED LIGO

Advanced LIGO will feature a quadruple suspension with a lower monolithic stage of fused silica in order to meet the seismic and thermal noise requirements. Fused silica ears are silicate bonded onto the polished flats of the test/penultimate mass and fused silica fibres, which are fabricated with a computer controlled CO₂ laser pulling machine, are then laser welded onto the ears. The whole process is robust and has been successfully demonstrated with eight test suspensions to date (six in Glasgow and two at LIGO MIT). In the second quarter of 2010 a monolithic quadruple suspension will be installed into the LIGO Advanced Systems Test Interferometer (LASTI) at MIT, Boston.