Multifocal diffractive ophthalmic lens using suppressed diffractive order
View Patent ↗A multifocal ophthalmic lens includes an ophthalmic lens and a diffractive element. The ophthalmic lens has a base curvature corresponding to a base power. The diffractive element produces constructive interference in at least four consecutive diffractive orders corresponding a range of vision between near and distance vision. The constructive interference produces a near focus, a distance focus corresponding to the base power of the ophthalmic lens, and an intermediate focus between the near focus and the distance focus. A diffraction efficiency of at least one of the diffractive orders is suppressed to less than ten percent.
1. A multifocal ophthalmic lens, comprising:
an ophthalmic lens having an anterior surface and a posterior surface; and
a diffractive element disposed on at least one of the anterior surface and the posterior surface, the diffractive element including a plurality of annular diffractive steps and four consecutive diffractive orders;
wherein:
the ophthalmic lens produces a near focus, an intermediate focus, and a distance focus each corresponding to a different one of the four consecutive diffractive orders; and
the plurality of annular diffractive steps of the diffractive element are configured such that one of the four diffractive orders is suppressed and at least a portion of the energy associated with that suppressed diffractive order is redistributed to one of the near focus, the intermediate focus, and the distance focus.
2. The lens of claim 1 , wherein the lens is an intraocular lens (IOL).
3. The lens of claim 2 , wherein the IOL is a posterior chamber IOL.
4. The lens of claim 3 , wherein the posterior chamber IOL is configured to be implanted in a capsular bag.
5. The lens of claim 1 , wherein:
the four consecutive diffractive orders include a lowest diffractive order, a highest diffractive order, and two intermediate diffractive orders; and
the suppressed diffractive order is one of the two intermediate diffractive orders.
6. The lens of claim 1 , wherein the four consecutive diffractive orders are (0, +1, +2, +3).
7. The lens of claim 6 , wherein the suppressed diffractive order is the +1 diffractive order.
8. The lens of claim 7 , wherein at least a portion of the energy associated with the +1 diffractive order is redistributed to the distance focus.
9. The lens of claim 1 , wherein the near focus corresponds to vision at 40 cm, and the intermediate focus corresponds to vision at 60 cm.
10. A multifocal ophthalmic lens, comprising:
an ophthalmic lens having a base curvature, an anterior surface, and a posterior surface; and
a diffractive element disposed on at least one of the anterior surface and the posterior surface, the diffractive element including a plurality of annular diffractive steps each having a corresponding step height relative to the base curvature, the plurality of annular diffractive steps including at least two repeating sets of three diffractive steps, the step heights for the three diffractive steps of each repeating set being defined as follows:
y
i
=
A
i
x
i
-
x
i
-
1
(
x
-
x
i
-
1
)
+
ϕ
i
(
i
=
1
,
2
,
3
)
wherein:
A i is a step height relative to the base curvature,
y i is a sag (height above or below the x-axis) in a segment i,
φ i is a relative phase delay from the x-axis, and
x i is a position of the step along the x-axis.