Variation on a Zernike wavefront sensor theme: Optimal use of photons V. Chambouleyron, O. Fauvarque, J-F. Sauvage, K. Dohlen, N. Levraud, A. Vigan, M. N’Diaye, B. Neichel and T. Fusco A&A, 650 (2021) L8 Published online: 15 June 2021 DOI: 10.1051/0004-6361/202140870