SPHERE extreme AO system On-sky operation, final performance and future improvements Fusco, Thierry ; Sauvage, Jean-Francois ; Mouilelt, David ; Beuzit, Jean-Luc ; Dohlen, Kjetil ; Petit, Cyril ; Beuzit, J. -L. ; Suarez, M. ; Soenke, C. ; Downing, M. ; Baudoz, P. ; Sevin, A. ; Baruffolo, A. ; Schmid, H. -M. ; Salasnich, B. ; Puget, P. ; Feautrier, F. ; Rochat, S. ; Moulin, T. ; Hugot, E. ; Vigan, A. ; Hubin, N. ; Puget, P. Abstract Publication: Adaptive Optics for Extremely Large Telescopes IV (AO4ELT4) Pub Date: October 2015 Bibcode: 2015aoel.confE..11F