| 主权项 |
1. A method for determining an ophthalmic lens comprising a front face and a rear face, the front face and the rear face each comprising a geometric center, a prescription being determined for a wearing of said lens by a wearer under usual wearing conditions, the method being implemented by computer and comprising steps for:
defining an optical target for said lens which complies with said prescription and a minimum thickness Wm of said lens; determining a first surface carried by a front face of a first virtual ophthalmic lens and a second surface carried by said rear face of said first virtual lens so that said first virtual lens complies with said prescription and possesses at each of its points a thickness greater than or equal to the minimum thickness Wm; determining a maximum thickness WM of said first virtual lens; determining a diameter DF and a height h; modeling a first aspherical continuous layer joining points forming a continuous surface, referenced with respect to a first datum defined by a first origin and a first system of axes, where the first continuous layer is configured so that the first origin is one of the points of the first continuous layer which comprises at this point a zero curvature according to one of said axes of said first system of axes and so that the points making up the first continuous layer which are separated from said axis by a radial distance of strictly less than DF/2 have a component according to said axis of strictly less than said height h; modeling a second aspherical continuous layer joining points forming a continuous surface, referenced with respect to a second datum defined by a second origin and a second system of axes, where the second continuous layer is configured so that the second origin is one of the points of the second continuous layer which comprises at this point a zero curvature according to one of the axes of the second system of axes; modeling an aspherical Fresnel layer on the basis of a cutting of said first continuous layer the Fresnel layer being referenced with respect to the first datum, where said Fresnel layer comprises a plurality of rings with aspherical profiles and a plurality of discontinuities located in a plane orthogonal to said axis passing through the first origin and delimiting said rings, said discontinuities being inscribed in one another, the discontinuity in which no discontinuity is inscribed being called the “first discontinuity”, said cutting is configured so that a circle of diameter DF centered on said first origin is inscribed in said first discontinuity; modeling a second virtual ophthalmic lens on the basis of the first virtual lens, where said Fresnel layer is added to one of the first or second surfaces of said first virtual lens so that the first origin is placed on the geometric center of the face which carries said Fresnel layer and where the second continuous layer is added to one of the first or second surfaces of said first virtual lens so that the second origin is placed on a predefined point of the face which carries said second continuous layer and where said second virtual lens possesses at at least one point a thickness equal to Wm; determining said Fresnel layer and said second layer by an optical optimization employing said optical target so that said second virtual lens complies with said prescription and so that it possesses a maximum thickness of strictly less than WM; and determining said ophthalmic lens as the second virtual lens. |
