Speaker
Description
Detector upgrades typically include increasing circulating power in the interferometer. In particular, next-generation detectors plan to have circulating powers in the MW range. Meanwhile, current detectors have achieved a few hundreds of kWs of circulating power, well below the intended design values. High power operation comes with a particular set of challenges, due to optical absorption at the test masses, which causes thermal deformation of the mirror and a shift of the cavity eigenmodes. In turn, these lead to increased optical losses and a plethora of control issues such as parametric instabilities.
Here, we present an experimental scheme using a phase camera to monitor the eigenmodes of a cavity while it is locked. In combination with the experimental scheme, we introduce a machine learning pipeline capable of deriving mirror aberrations in a table-top linear cavity from the phase camera data. This is achieved by mapping the cavity eigenmode amplitudes into Zernike mode coefficients which describe the various mirror aberrations. We will present experimentally measured modal amplitudes of an optical cavity in a tabletop set-up and discuss the next steps. Such an ability to monitor cavity mirror deformations in the presence of high circulating power will be crucial when dealing with the long thermal transients that are expected in next-generation detectors.