Large scale laser interferometric gravitational wave detectors (GWDs), such as GEO 600 require high quality optics to reach their design sensitivity. The inevitable surface imperfections, inhomogeneities and light-absorption induced thermal lensing in the optics can convert laser light from the fundamental mode to unwanted higher order modes, and pose challenges to the operation and sensitivity of the GWDs. Here we demonstrate the practical implementation of a thermal projection system which reduces those unwanted effects via targeted spatial heating of the optics. The thermal projector consists of 108 individually addressable heating elements which are imaged onto the beam splitter of GEO 600. We describe the optimization of the spatial heating profile and obtained results.
@article{arxiv.1806.01652,
title = {Matrix Heater in the Gravitational Wave Observatory GEO 600},
author = {Holger Wittel and Christoph Affeldt and Aparna Bisht and Suresh Doravari and Hartmut Grote and James Lough and Harald Lück and Emil Schreiber and Kenneth A. Strain and Karsten Danzmann},
journal= {arXiv preprint arXiv:1806.01652},
year = {2018}
}