Diffractive multi-focal lens

• US 5,760,871 A
• Filed: 11/30/1993
• Issued: 06/02/1998
• Est. Priority Date: 01/06/1993
• Status: Expired due to Fees

• Current Assignee: Holo Ltd.
• Original Assignee: Holo Ltd.
• Inventors: Kedmi, Joseph, Levy, Uri, Grossinger, Israel, Kosoburd, Tatiana
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US08/159,728
• Time in Patent Office: 1,645 Days
• Field of Search: 351/160 R, 351/160 H, 351/161, 351/162, 359/569, 359/571, 359/574, 359/665, 623/6
• US Class Current: 623/6.3
• CPC Class Codes: A61F 2/1613 having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
• CPC Class Codes: A61F 2/1618 Multifocal lenses
• CPC Class Codes: A61F 2/1654 Diffractive lenses
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08
• CPC Class Codes: G02B 5/1895 such optical elements having dioptric power
• CPC Class Codes: G02C 2202/20 Diffractive and Fresnel lenses or lens portions
• CPC Class Codes: G02C 7/042 Simultaneous type
• CPC Class Codes: G02C 7/044 Annular configuration, e.g. pupil tuned

Abstract

A tri-focal diffractive lens defining three foci, for viewing a band of light having a representative wavelength of λ, including a diffractive surface having a number of optical heights, h_o, wherein the difference between the highest and the lowest optical heights is, modulo λ, substantially different from λ/2, wherein each of the foci receives at least 20% of light incident on the lens.

Claims

1. A multi-focal diffractive lens having a diffractive surface and a plurality of diffractive orders, the surface having an optical height, h_o, relative to a bese reference surface which is a periodic function, each period of which is given by:

space="preserve" listing-type="equation">H·

exp{ (u-u.sub.0)/W.sub.1 !.sup.m1 } for u≦

u.sub.0 ;

and

space="preserve" listing-type="equation">H·

exp{ (u-u.sub.0)/W.sub.2 !.sup.m2 } for u≧

u.sub.0,

wherein u₀ =2 π

W₁ /(W₁ +W₂), wherein H, W₁, W₂, m₁ and m₂ are preselected constants, wherein W₁ may be the same as or different from W₂ and m₁ may be the same as or different from m₂, wherein u is a function of r namely u(r) and, wherein the imaging efficiency of each of the diffractive order is not less than twenty percent.

2. A multi-focal lens according to claim 1 wherein the fraction of the total incident energy carried by each of three of the dominant orders is substantially equal.

3. A multi-focal lens according to claim 1 wherein the phase of said periodic function is preselected so as to provide a different proportion of the incident light to at least one of the foci at different lens openings.

4. A multi-focal diffractive lens according to claim 1 comprising a diffractive surface, having a surface topography including local minima and maxima, operative to focus light in accordance with a plurality of dominant diffraction orders defining a plurality of respective foci, wherein the imaging efficiency of each of the orders is not less than twenty percent and wherein the radius of curvature of the diffractive surface, at any given point on the surface, is equal to at least twice the difference in topographical height between the local minimum nearest to the given point and the local maximum nearest to the given point.

5. A multi-focal lens according to claim 4 wherein the radius of curvature of the diffractive surface, at any given point on the surface, is equal to at least ten times the difference in topographical height between the local minimum nearest to the given point and the local maximum nearest to the given point.

6. A multi-focal lens according to claim 1 wherein the lens is a contact lens adapted for placement on the cornea of a wearer.

7. A multi-focal lens according to claim 1 wherein the lens is an intraocular lens adapted for replacement of the natural lens of a wearer.

8. A multi-focal lens according to claim 1 comprising a first portion and a second portion each having two surfaces and an edge, wherein the diffractive surface comprises a surface of the first portion facing a surface of the second portion.

9. A multi-focal lens according to claim 8 wherein the diffractive surface touches the facing surface of the second portion, and wherein the edges of the two portions are sealed to form a sandwich structure having the diffractive surface interior to the sandwich.

10. A multi-focal lens according to claim 1 usable with light within a given wavelength band, wherein the band is represented by a typical wavelength.

11. A multi-focal lens according to claim 10 wherein the typical wavelength is approximately equal to 0.555 micrometers.

12. A multi-focal lens according to claim 6 comprising a refractive surface.

13. A multi-focal lens according to claim 7 comprising a refractive surface.

14. A multi-focal lens according to claim 1 wherein the lens is a contact lens adapted for placement on the cornea of a wearer.

15. A multi-focal lens according to claim 3 wherein the lens is a contact lens adapted for placement on the cornea of a wearer.

16. A multi-focal lens according to claim 1 comprising a first portion and a second portion each having two surfaces and an edge, wherein the diffractive surface comprises a surface of the first portion facing a surface of the second portion.

17. A multi-focal lens according to claim 3 comprising a first portion and a second portion each having two surfaces and an edge, wherein the diffractive surface comprises a surface of the first portion facing a surface of the second portion.

18. A multi-focal lens according to claim 1 wherein the sum of the efficiencies of three of the diffractive orders is at least 85%.

19. A multi-focal lens according to claim 3 wherein the sum of the efficiencies of three of the diffractive orders is at least 85%.

20. A multi-focal lens according to claim 1 and further comprising a refractive surface.

21. A multi-focal lens according to claim 3 and further comprising a refractive surface.

22. A multi-focal diffractive lens according to claim 4 wherein the radius of curvature of the diffractive surface, at any given point on the surface, is equal to at least fifty times the difference in topographical height between the local minimum nearest to the given point and the local maximum nearest to the given point.

23. A multi-focal diffractive lens comprising a diffractive surface, having a surface topography including local minima and maxima, operative to focus light in accordance with a plurality of dominant diffraction orders defining a plurality of respective foci,

wherein the surface topography of the diffractive surface has no discontinuities in the first derivative;

wherein the imaging efficiency of each of the dominant orders is not less than twenty percent,

and wherein the radius of curvature of the diffractive surface, at any given point on the surface, is equal to at least twice the difference in topographical height between the local minimum nearest to the given point and the local maximum nearest to the given point.

24. A multi-focal lens according to claim 23 wherein the radius of curvature of the diffractive surface, at any given point on the surface, is equal to at least ten times the difference in topographical height between the local minimum nearest to the given point and the local maximum nearest to the given point.

25. A multi-focal lens according to claim 23 wherein the radius of curvature of the diffractive surface, at any given point on the surface, is equal to at least fifty times the difference in topographical height between the local minimum nearest to the given point and the local maximum nearest to the given point.

26. A multi-focal lens according to claim 23 wherein the fraction of the total incident energy carried by each of the dominant orders is substantially equal.

27. A multi-focal lens according to claim 23 wherein the lens is a contact lens adapted for placement on the cornea of a wearer.

28. A multi-focal lens according to claim 23 comprising a first portion and a second portion each having two surfaces and an edge, wherein the diffractive surface comprises a surface of the first portion facing a surface of the second portion.

29. A multi-focal lens according to claim 24 comprising a first portion and a second portion each having two surfaces and an edge, wherein the diffractive surface comprises a surface of the first portion facing a surface of the second portion.

30. A multi-focal lens according to claim 23 wherein the sum of the efficiencies of three of the dominant diffraction orders is at least 85%.

31. A multi-focal lens according to claim 24 wherein the sum of the efficiencies of three of the dominant diffraction orders is at least 85%.

32. A multi-focal lens according to claim 25 wherein the sum of the efficiencies of three of the dominant diffraction orders is at least 85%.

33. A multi-focal lens according to claim 23 and further comprising a refractive surface.

34. A contact lens comprising:

a first portion and a second portion each having two surfaces and an edge, wherein at least one surface of one of the portions comprises a diffractive surface wherein the diffractive surface faces a surface of the second portion, wherein the two portions are sealed to form a sandwich structure having a sealed third interior portion which is filled with a liquid and having the diffractive surfaces interior to the sandwich and wherein one of outer surfaces of the sandwich structure is adapted to contact the cornea of a user.

35. A contact lens according to claim 34 wherein the diffractive surface touches the facing surface of the second portion.

36. A composite contact lens comprising:

a first portion and a second portion forming a sandwich structure;

said first portion having at least one optical element in relief thereon;

said second portion having generally smooth interior and exterior surfaces;

wherein said interior surface faces said optical element;

wherein the top of the relief of the optical element touches the interior surface thereby spacing the two portions and forming a well defined optical structure and wherein the optical structure between the two portions is filled with a liquid.

37. A lens according to claim 36 and wherein the spacing between said two portions defines a sealed interior portion.

38. A contact lens according to claim 36 wherein the optical element in relief is a diffractive element.

39. A composite contact lens comprising:

a first portion and a second portion forming a sandwich structure;

said first portion having at least one optical element in relief thereon;

said second portion having at least one smooth surface facing said optical element;

wherein the distance from a point on said facing surface, opposite the base of the relief of said optical element, is substantially equal to the height of the top of the relief;

wherein the sandwich structure between the first portion and second portion is filled with a liquid.

40. A contact lens according to claim 39 wherein the optical element in relief is a diffractive element.