Small aperture multifocal
First Claim
1. An optical device comprising an optical region disposed about an optical axis and a phase zone plate disposed in the optical region for causing light passing through the phase zone plate to converge to a plurality of focal points, the phase zone plate comprising a plurality of blazed facets which include a plurality of annular concentric zones spaced according to the formula ##EQU5## where k is an integer zone number measured along the device radially outward from the optical axis to the periphery of the phase zone plate, and rk are half-period zone radii, the zones including odd and even zones in accordance with the value of k as k alternates progressively odd and even from the optical axis to the periphery of the phase zone plate, the depth of the zones at the even zone radii r2, r4, r6, . . . being about one-half the depth of the zones at the odd zone radii r1, r3, r5, . . . , a discontinuous interface being disposed between selected pairs of adjacent odd and even half-period zones at the odd zone radii r1, r3, r5, . . . , each selected pair of adjacent odd and even zones forming a continuous profile.
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Accused Products
Abstract
An optical device suitably employable in intraocular and contact lenses that employs a phase zone plate of a Cohen lens design that relies on a small number of zones to provide multifocal images.
164 Citations
34 Claims
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1. An optical device comprising an optical region disposed about an optical axis and a phase zone plate disposed in the optical region for causing light passing through the phase zone plate to converge to a plurality of focal points, the phase zone plate comprising a plurality of blazed facets which include a plurality of annular concentric zones spaced according to the formula ##EQU5## where k is an integer zone number measured along the device radially outward from the optical axis to the periphery of the phase zone plate, and rk are half-period zone radii, the zones including odd and even zones in accordance with the value of k as k alternates progressively odd and even from the optical axis to the periphery of the phase zone plate, the depth of the zones at the even zone radii r2, r4, r6, . . . being about one-half the depth of the zones at the odd zone radii r1, r3, r5, . . . , a discontinuous interface being disposed between selected pairs of adjacent odd and even half-period zones at the odd zone radii r1, r3, r5, . . . , each selected pair of adjacent odd and even zones forming a continuous profile.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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5. The optical device of claim 1 wherein the phase zone plate includes a surface having a parabolic repetitive profile.
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6. The optical device of claim 1 in the form of either an intraocular or contact lens.
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7. The optical device of claim 2 in the form of either an intraocular or contact lens.
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8. The optical device of claim 3 in the form of either an intraocular or contact lens.
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9. The optical device of claim 4 in the form of either an intraocular or contact lens.
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10. The optical device of claim 5 in the form of either an intraocular or contact lens.
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11. The optical device of claim 6 in the form of an intraocular lens.
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12. The optical device of claim 7 in the form of an intraocular lens.
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13. The optical device of claim 8 in the form of an intraocular lens.
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14. The optical device of claim 9 in the form of an intraocular lens.
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15. The optical device of claim 6 in the form of a contact lens.
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16. The optical device of claim 7 in the form of a contact lens.
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17. The optical device of claim 8 in the form of a contact lens.
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18. The optical device of claim 9 in the form of a contact lens.
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19. The optical device of claim 10 in the form of a contact lens.
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20. A diffractive bifocal ophthalmic ocular lens comprising annular concentric zones spaced according to the formula ##EQU6## where k is a positive integer representing the respective zones, λ
- is a design wavelength in the visible spectrum, d is the first order focal length, and rk represents the respective zone radii, a discontinuous step being disposed only at the odd zone radii r1, r3, r5, . . . , each step having an optical path length approximately equal to λ
/2.
- is a design wavelength in the visible spectrum, d is the first order focal length, and rk represents the respective zone radii, a discontinuous step being disposed only at the odd zone radii r1, r3, r5, . . . , each step having an optical path length approximately equal to λ
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21. An ophthalmic ocular lens with two primary focal points, the lens comprising a central zone and a plurality of peripheral blazed annular concentric zones, the zones being spaced substantially proportional to √
- k, with k being an integer zone number, each zone having a zone boundary, and a discontinuous step being disposed only at the odd zone boundaries, the discontinuous steps having a depth substantially equal to two times the depth of the central zone, the zones being disposed so that approximately 40% of the incident light at a design wavelength λ
in the visible spectrum is focussed to each of the two primary focal points. - View Dependent Claims (22, 23, 24, 25, 26, 27)
- k, with k being an integer zone number, each zone having a zone boundary, and a discontinuous step being disposed only at the odd zone boundaries, the discontinuous steps having a depth substantially equal to two times the depth of the central zone, the zones being disposed so that approximately 40% of the incident light at a design wavelength λ
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28. A diffractive bifocal ophthalmic ocular lens for focusing light to two bifocal powers, the lens comprising a central zone and a plurality of peripheral blazed annular concentric zones disposed about the central zone, selected zones being separated by steps, the steps having essentially the same step height, the step height being substantially equal to two times the depth of the central zone, the annular area between adjacent steps being substantially equal to two times the annular area of the central zone, the zones being disposed so that the intensity of light focussed at each of the two bifocal powers is equal to about 0.40 of the incident light at a design wavelength λ
- within the visible spectrum.
- View Dependent Claims (29, 30, 31, 32, 33, 34)
Specification