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EP0351471B1
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Multifocal diffractive optical device
Assignee: Individual
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Filing: 1988-11-10
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Granted: 1996-01-31
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Expires: 2008-11-10
Abstract
Abstract A multifocal ophthalmic lens having diffractive power has a central zone and a plurality of peripheral annular concentric zones. The peripheral zones include a stepped facet, each stepped facet having an outer corner with at least one outer corner being defined by a smooth curve. At least one inner corner can also be defined by a smooth curve. The facet profile preferably varies smoothly without discontinuities. <IMAGE>
Inventors
- 👤 Allen L. Dr. Cohen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 18:33
CPC Classifications
G; G02; G02C; G02C7/00; G02C7/02; G02C7/04; G02B; G02B5/00; G02B5/18; G02B5/1876; G02B5/189; G02B5/1895; G02C7/024; G02C7/028; G02C7/041; G02C7/042; G02C7/044; G02C7/06; G02C2202/00; G02C2202/20
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
Multifocal diffractive optical element comprising a zone plate containing annular concentric zones which are spaced substantially proportional to √n being an integer, said zones including a facet having a facet depth D₀ and having a profile for introducing a difference in optical path length, characterized in that said profile is shaped such that for a predetermined design wavelength the facet depth D₀ is less than one half of said design wavelength divided by the difference of the refractive indices of the element material and the surrounding medium and such that the intensity of light of said design wavelength is substantially equally distributed in two of the diffractive foci of the lens.
Claim 2
Dependent Claim
45 words
A multifocal diffractive optical element according to claim 1 wherein said profile is designed such as to direct light of said design wavelength to said two diffractive foci with intensities about 0.40 of the intensity of the design wavelength light incident upon said optical element.
Claim 3
Dependent Claim
19 words
A multifocal diffractive optical element according to claim 1 or 2 wherein the facet profile varies smoothly without discontinuities.
Claim 4
Dependent Claim
71 words
A multifocal diffractive optical element according to claim 1, 2, or 3 wherein the profile satisfies the following equation: d = D 0 x {½ + ½ x cos (π x r 2 /b 2 )} where d is the depth of the repetitive profile, r is the radial position of the zone, b is the radius of the 1st zone, and D₀ is the facet depth at the design wavelength.
Claim 5
Dependent Claim
26 words
A multifocal diffractive optical element according to any one of the preceding claims wherein each stepped facet has an outer corner defined by a smooth curve.
Claim 6
Dependent Claim
26 words
A multifocal diffractive optical element according to any one of the preceding claims wherein each stepped facet has an inner corner defined by a smooth curve.
Claim 7
Dependent Claim
22 words
A multifocal diffractive optical element according to any one of the preceding claims wherein light of the design wavelength is yellow light.
Claim 8
Dependent Claim
20 words
A multifocal diffractive optical element according to any one of the preceding claims in the form of an ophthalmic lens.
Claim 9
Dependent Claim
22 words
A multifocal diffractive optical element according to claim 8 in the form of one of a contact lens or an intraocular lens.
Claim 10
Dependent Claim
35 words
An ophthalmic contact lens containing at least two phase zone plates within its optic zone, at least one of which contains a multifocal diffractive optical element according to any one of claims 1 to 7.
Claim 11
Dependent Claim
34 words
An ophthalmic contact lens having within its optic zone: a phase zone plate which contains a multifocal diffractive optical element according to any one of claims 1 to 7 and a pure refractive portion.
Claim 12
Dependent Claim
24 words
A multifocal diffractive ophthalmic lens according to any one of the preceding claims having stepped facets, each stepped facet having a rounded outer corner.
References Cited (Backward Citations)
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