ICTS

The Einstein Telescope (ET) aims to extend ground based gravitational wave observations deep into the low frequency regime, where seismic and suspension thermal noise become a dominant limitation. The residual motion of the suspended optics significantly impact the detector sensitivity we target to achieve. This talk outlines the resulting vibration isolation requirements for ET-LF. I would be presenting ongoing work focusing on sensing reference mass motion using HoQI sensors and our OmniSens experiment which could inform demonstrations for the design of ET-like isolation systems.