Development of Fused Silica Suspensions for aLIGO and the spin-off into MEMS


Development of Fused Silica Suspensions for aLIGO and the spin-off into MEMS

Hercus Theatre
Physics South Building


The Laser Interferometer Gravitational Wave observatory comprises two detectors located in Hanford, WA and Livingston LA. These detectors are 4km long Fabry-Perot Michelson interferometers and the most sensitive length measuring devices in the world. They are able to sense a length change equivalent to 1/1000th the diameter of a proton over their 4km baseline. In 2015 the gravitational wave window on the Universe was opened with the detection of the gravitational wave signal form a pair of binary black holes (GW150914). Additional signals which followed in observing run 2 included further binary black holes and GW170817, a neutron star binary. This latter signal enabled the most precise constraint on the speed of gravity and a measurement of the Hubble constant. Essential to the improvement in the low frequency performance of the aLIGO detectors, and the subsequent detections, is the UK designed and built fused silica suspensions. This activity is led by University of Glasgow and required techniques to fabricate and test glass suspensions capable of suspending 40kg optics on four 400 micron diameter fibres. In this talk, I will describe the motivation for using glass suspensions, the R&D required to build/commission aLIGO, and the activities which I lead on the suspension design & development for future upgrades including A+. I will also describe my work in translating fundamental research from the field of gravitational wave detection into applied gravity sensing; with applications in oil & gas prospecting, security & defence and environmental monitoring. I will detail the design of the Glasgow MEMS gravimeter system, a collaboration between Physics & Engineering funded under the UK Quantum technology programme, including the novel low frequency flexure architecture and the construction of a high sensitivity, long term stable, optical shadow sensor. I will detail the development of a field portable system that can operate outside of the laboratory, capable of measuring vertical gravity changes within the Physics building in Glasgow. Finally, I will provide an outlook of the direction of the research group, the current efforts to commercialise this technology


  • Professor Giles Hammond
    Professor Giles Hammond, University of Glasgow