Thermal correction of astigmatism in the gravitational wave observatory GEO 600

Wittel, H. et al. (2014) Thermal correction of astigmatism in the gravitational wave observatory GEO 600. Classical and Quantum Gravity, 31(6), 065008. (doi: 10.1088/0264-9381/31/6/065008)

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The output port of GEO 600 is dominated by unwanted higher order modes (HOMs). The current thermal actuation system, a ring heater behind one of the folding mirrors, causes a significant amount of astigmatism, which produces HOMs. We have built and installed an astigmatism correction system, based on heating this folding mirror at the sides (laterally). With these side heaters and the ring heater behind the mirror, it is possible to tune its radius of curvature in the horizontal and the vertical degree of freedom. We use this system to match the mirrors in the two arms of GEO 600 to each other, thereby reducing the contrast defect. The use of the side heaters reduces the power of the HOMs at the output of GEO 600 by approximately 37%.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Strain, Professor Kenneth
Authors: Wittel, H., Lück, H., Affeldt, C., Dooley, K.L., Grote, H., Leong, J.R., Prijatelj, M., Schreiber, E., Slutsky, J., Strain, K., Was, M., Willke, B., and Danzmann, K.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Classical and Quantum Gravity
Publisher:Institute of Physics Publishing Ltd.
ISSN (Online):1361-6382

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