METHOD FOR DETERMINING A SURFACE OF AN OPHTHALMIC LENS COMPRISING A CARRIER AND A FRESNEL MEMBRANE, AND OPHTHALMIC LENS COMPRISING SUCH A SURFACE

摘要

The invention relates to a method for determining a surface of an ophthalmic lens comprising a carrier and a Fresnel membrane lying on the carrier. The invention also relates to an ophthalmic lens comprising such a surface. The invention especially relates to a method for determining a surface of an ophthalmic lens, where said surface comprises a Fresnel membrane and a carrier supporting said Fresnel membrane. Said carrier has a geometric centre, a first central region (10) and an annular peripheral region (15), and a rotational symmetry. Said Fresnel membrane, the first central region and the peripheral region are centered on said geometric centre, the first central region being defined by a first circular border, and the peripheral region being defined by a second circular border and by the edge of the surface. The method comprises steps of:(SI) determining a first curvature profile of said carrier in said first central region and a second curvature profile of said carrier in said peripheral region; (S10) determining a first radius (R1) of said first border and a second radius (R2) of said second border; (S20) determining a third curvature profile of a transition region (12) of said carrier, where said transition region is adjacent to the first central region and to said peripheral region; (S30) determining a target curvature profile of the surface where said target curvature profile is identical in said first central region to the first curvature profile of the carrier; (S40) determining a continuous curvature profile for the Fresnel membrane from a difference between said target curvature profile and said curvature profile of the carrier; and (S50) determining the Fresnel membrane by cutting said continuous curvature profile for the Fresnel membrane.