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Mechanical triple pendulum transfer function for use in SQL measurement of single arm test.

November 25, 2015 @ 11:00 am - 12:30 pm

Speaker: Md Aftab Baig (EE13S008)

Gravitational waves (GWs) are transverse waves travelling with the speed of light. The waves propagate unruffled in space and carry information of the source as they weakly interact with matter. The detection of gravitational waves using ground based interferometers such as LIGO is affected with noise sources such as seismic noise, thermal noise and photon shot noise. Multi stage pendulum isolation suspension systems reduce the seismic noise caused due to ocean tides, earthquakes etc.

To aid the detection of gravitational waves, a seismic suspension system capable of detecting displacements of the order of 10-18 √Hz is needed at the AEI (Albert Einstein institute) 10m prototype. The three stage suspension, filters seismic noise of magnitude 10-8 √Hz above its resonant frequency. The alignment and control of the suspension chain in various degrees of freedom at the top and penultimate stages of the suspension is done using electro magnet actuators. Passive eddy-current damping is provided at the top mass to dampen the resonant modes of the pendulum.

A novel contact free electro-static actuation was built for longitudinal fine tuning of the Fabry-Perot cavity by actuating the mirror of the suspension chain, and the design validated using finite element simulations. The functionality of the cascaded pendulum was examined with the aid of a transfer function obtained using an optical lever along with Control data system (CDS). An analytical model of the suspension has been developed at AEI to check the appropriateness of the built triple pendulums. Optimization of the parameters was carried out to achieve a good fit between the model and suspension system and to study the effect of parameters on the resonant frequencies.

All are cordially invited.


November 25, 2015
11:00 am - 12:30 pm
Event Category:


ESB 244


Dr. Anil Prabhakar
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