Patent ID: 11963868
Assignee: AST PRODUCTS, INC.
Field: Medical technology (Instruments)
Classification: CPC A  G | IPC A

Claim 0:
1. A diffractive trifocal lens comprising a lens body, the lens body comprising:
(a) a first aspheric surface; and
(b) a second aspheric surface comprising a central zone and a plurality of diffractive elements comprising concentric annular zones extending in a radial direction, each concentric annular zone having a periodically structured curve comprising two smooth turning points between two sharp turning points, wherein a slope of the periodically structured curve changes sign at each of the two smooth turning points in each of the concentric annular zones, thereby producing a near focus (f2), an intermediate focus (f1), and a distance focus (f0),
wherein a modulation transfer function (MTF) of the diffractive trifocal lens comprises a first peak at the intermediate focus (f1) and a second peak at the near focus (f2), and
wherein a most minimum value of the MTF between the first peak and the second peak is about 50% of a most maximum value of the MTF at the first peak, thereby improving vision contrast between the intermediate focus (f1) and the near focus (f2); and
wherein:
an optical power of the distance focus (f0) is greater than or equal to 0 diopters and less than or equal to 55 diopters;
an optical power of the intermediate focus (f1) is greater than the optical power of the distance focus (f0) by a first difference in optical power that is greater than or equal to 1 diopter and less than or equal to 2.5 diopters; and
an optical power of the near focus (f2) is greater than the optical power of the distance focus (f0) by a second difference in optical power that is greater than or equal to 2 diopters and less than or equal to 5 diopters.