| 主权项 |
1. An ophthalmic lens comprising:
an anterior surface; a posterior surface; an optic axis; and at least one diffractive grating pattern disposed on at least one of the anterior surface and the posterior surface, the at least one diffractive grating pattern including a plurality of annular zones corresponding to a plurality of distance ranges from the optic axis, each of the plurality of zones having a plurality of echelettes having a radius of curvature corresponding to a focal length, the radius of curvature for each of the plurality of zones being different from the radius of curvature for another of the plurality of zones, wherein each of the plurality of echelettes has a step height, the step height for each of the plurality of zones being the same for all of the plurality of zones, wherein the radius of curvature for each of the plurality of zones changes monotonically with a zone distance from the optic axis, wherein the focal length corresponding to the radius of curvature for each of the plurality of zones changes monotonically with a zone distance from the optic axis, wherein each zone has a depth of field, wherein the depth of field for the ophthalmic lens is extended beyond that of a single zone by blending of the depths of field of the plurality of zones, and wherein a local period of the diffractive grating pattern is given by Λ=fλ/r, where Λ is the period, f is the focal length of the diffractive surface of a zone, r is the distance from the optic axis, and λ is the wavelength of light. |
