Matrix Heater in the Gravitational Wave Observatory GEO 600

TL;DR

This paper presents a thermal projection system with 108 individually controllable heaters that improves the optical quality of GEO 600's beam splitter by reducing thermal lensing effects caused by surface imperfections.

Contribution

The study demonstrates a practical implementation of a targeted thermal heating system with optimized spatial profile to mitigate thermal lensing in gravitational wave detector optics.

Findings

Effective reduction of thermal lensing effects in GEO 600

Implementation of a 108-element thermal projector system

Enhanced optical performance of the beam splitter

Abstract

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.