Improving VLT/SPHERE without additional hardware: First on-sky correction of quasi-static aberrations using the dark hole technique

Direct imaging is the primary technique currently used to detect young and warm exoplanets and understandtheir formation scenarios. The extreme flux ratio between an exoplanet and its host star requires the use ofcoronagraphs to attenuate the starlight and create high contrast images. However, their performance is limitedby wavefront aberrations that cause stellar photons to leak through the coronagraph and on to the science detectorpreventing the observation of fainter extrasolar companions. The VLT/SPHERE instrument takes advantage ofits efficient adaptive optics system to minimize dynamical aberrations to improve the image contrast. In goodseeing conditions, the performance is limited by quasi-static aberrations caused by slowly varying aberrationsand manufacturing defects in the optical components. The mitigation of these aberrations requires additionalwavefront sensing and control algorithms to enhance the contrast performance of SPHERE. Dark hole algorithmsinitially developed for space-based application and recently performed on SPHERE calibration unit have shownsignificant improvement in contrast. This work presents a status update of dark hole algorithms applied onSPHERE and the results obtained during the on-sky tests performed on February 15th and March 15th 2022.