Speaker
Description
Optical aberrations in gravitational wave detectors arise mainly from laser absorption in coatings and manufacturing defects in the optics along the beam path. If left uncorrected, these distortions drive the interferometer away from its optimal operating point, degrading both stability and sensitivity. Future detectors, such as the Einstein Telescope–High Frequency, will operate with unprecedented circulating power, further increasing the impact of these aberrations.
In Advanced Virgo, axisymmetric aberrations are compensated using thermal actuators and CO₂–based correction systems. However, residual non–axisymmetric wavefront distortions remain a significant challenge in the next–generation detectors due to the increase of circulating power. We investigate the use of Deformable Mirrors (DMs) as a flexible solution to compensate for these asymmetric distortions. By shaping the phase of an auxiliary CO₂ beam upon reflection, DMs can project the required non–axisymmetric intensity pattern onto the compensation plates, where the CO2 radiation is locally and fully absorbed to produce a corrective thermal lens for the main beam of the interferometer, without introducing frequency–dependent noise within the detector sensitive band.
We present the numerical tools developed to model the projection strategy and to demonstrate the feasibility of reproducing the typical target intensity patterns. We also discuss the experimental study that confirms the capability of DMs to generate the required corrective profiles and the impact of the DM-based correction in the Advanced Virgo upgraded layout for O5.