Design of optical surfaces conform the hyperbolic Monge-Ampère equation M.W.M.C. Bertens, M.J.H. Anthonissen, W.L. IJzerman and J.H.M. ten Thije Boonkkamp EPJ Web Conf., 266 (2022) 02003 Published online: 13 October 2022 DOI: 10.1051/epjconf/202226602003