M2 : Study of scattered light in the detection system of the Virgo interferometer.

Detector performance may be limited by light scattering. Indeed, if a small fraction of the light scattered by the interferometer mirrors recombines with the main beam by travelling a parasitic optical path, this risks producing noise which could limit the detector’s sensitivity. This risk is particularly acute in the vacuum-suspended optical benches that detect laser beams at the interferometer’s output ports. These benches, for which the LAPP is responsible, are called detection benches because they convert the optical signals contained in the laser beams into digital signals. The proposed internship deals with this issue. The internship will be developed along three lines. Firstly, a study of the effects of scattered light on detector sensitivity, through analysis of the data collected at the experiment site. Secondly, simulation of the effects of scattered light on instrument sensitivity. And finally, the preparation of improvements to the detection benches to be installed at the end of the next data collection. To this end, the trainee will also be able to perform scattered light measurements using an optical set-up available in one of the laboratory’s clean rooms, in order to qualify some of the elements used on the detection benches.

Possible indication of an opening towards a thesis subject: : This internship is intended to lead to a thesis. In fact, this work concerns both the Virgo detector currently installed, and its upgraded version, due to be installed in 2025.