Diffractive lenses for vision correction

• US 20060055883A1
• Filed: 07/13/2005
• Published: 03/16/2006
• Est. Priority Date: 08/20/2004
• Status: Active Grant

• Current Assignee: Apollo Optical Systems LLC
• Original Assignee: Apollo Optical Systems LLC
• Inventors: Morris, G. Michael, Federico, Richard J., Buralli, Dale A.
• Granted Patent: US 7,156,516 B2
• Time in Patent Office: Days
• US Class Current: 351/168
• 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 2/1648 Multipart lenses
• CPC Class Codes: A61F 2/1654 Diffractive lenses
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• 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 7/028 Special mathematical design techniques
• CPC Class Codes: G02C 7/042 Simultaneous type
• CPC Class Codes: G02C 7/044 Annular configuration, e.g. pupil tuned
• CPC Class Codes: G02C 7/06 bifocal; multifocal ; progressive G02C7/041 takes precedence

Abstract

Diffractive lenses for vision correction are provided on a lens body having a first diffractive structure for splitting light into two or more diffractive orders to different focal distances or ranges, and a second diffractive structure, referred to as a multiorder diffractive (MOD) structure, for diffracting light at different wavelengths into a plurality of different diffractive orders to a common focal distance or range. In a bifocal application, the first and second diffractive structures in combination define the base power for distance vision correction and add power for near vision correction of the lens. The first and second diffractive structures may be combined on the same surface or located on different surfaces of the lens. The first diffractive structure may have blazed (i.e., sawtooth), sinusoidal, sinusoidal harmonic, square wave, or other shape profile. A sinusoidal harmonic diffractive structure is particularly useful in applications where smooth rather than sharp edges are desirable.

Claims

1. A diffractive optical element comprising:

at least one diffractive structure having a plurality of zones wherein each of the zones has locations in accordance with the equation

$z<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{\xi <br><br>}\right)=\underset{j=1}{\overset{j_{\max }}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>a_j<br><br>\cos <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(2<br><br>\mathrm{\pi <br><br>j}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\xi <br><br>}+{\mathrm{\varphi <br><br>}}_j\right)$

wherein a_j and φ

_j are the amplitude and phase, respectively, of a finite number of terms j from 0 to j_max, and ξ

is a fractional position at or between zero and one within the zone.

2. The diffractive optical element according to claim 1 wherein said structure is smoothly varying.

3. The diffractive optical element according to claim 1 wherein said structure is continuous within each of the zones and at the boundaries between zones, thereby providing said structure without sharp edges.

4. The diffractive optical element according to claim 1 wherein said diffractive structure diffracts light into at least two diffractive orders to different focal distance or ranges.

5. The diffractive optical element according to claim 1 wherein said diffractive structure represents a first diffractive structure for diffracting light into at least two diffractive orders to different focal distance or ranges, and said diffractive optical element further comprises a second diffractive structure for diffracting light into a plurality of different diffractive orders to a common focal distance or range.

6. The diffractive optical element according to claim 1 further comprising a lens body having said diffractive structure and said lens body is shaped to provide a refractive optical power to said optical element.

7. An ophthalmic lens comprising:

a lens body having first and second surfaces;

a first diffractive structure for splitting light of different wavelengths into two or more diffractive orders to different focal distances or ranges;

a second diffractive structure for diffracting light into a plurality of different diffractive orders to a common focal distance or range, in which said first and second diffractive structures are located on the same or different ones of said first and second surfaces; and

said first and second diffractive structures in combination provide at least near and distance vision correction, in which said first diffractive structure represents a sinusoidal harmonic diffractive structure having a plurality of zones that is continuous within each of the zones and at the boundaries between zones.

8. The lens according to claim 7 wherein said lens represents a contact lens, said one of said first and second surfaces upon which said first diffractive element is located represents the surface of said lens to be positioned onto an eye of a user.

9. The lens according to claim 8 wherein said lens when positioned onto the eye of the user is worn comfortably by the user as said first diffractive structure is without sharp edges capable of irritating the eye.

10. The lens according to claim 7 wherein:

said second diffractive structure has a second power;

said first diffractive structure has at least two different first powers in accordance with each of said diffractive orders of said first diffractive structure;

said lens has a base power for said distance vision correction in accordance with the combination of said second power of said first diffractive structure with one of said first powers of said first diffractive structure; and

said lens has an add power for said near vision correction in accordance with the combination of said second power of said second diffractive structure with another one of said first powers of said first diffractive structure.

11. The lens according to claim 10 wherein said second power of said second diffractive structure mainly or entirely contributes in said combination with said first diffractive structure to said base power of said lens.

12. The lens according to claim 7 wherein said second diffractive structure represents a multiorder diffractive structure characterized by a plurality of zones which define zone boundaries at which light incident on the diffractive structure experiences an optical phase shift, and which diffract light of each of said wavelengths in a different diffractive order, m, such that the magnitude of m≧

1, to the focal distance or range for the diffractive structure.

13. The lens according to claim 7 wherein said lens body has two sides providing said first and second surfaces, respectively, and said first surface is along one of said sides representing the front of said lens, and said second surface is along another one of said sides representing the back of said lens.

14. The lens according to claim 7 wherein said lens body has two sides providing said first and second surfaces, respectively, and said second surface is along one of said sides representing the front of said lens, and said first surface is along another one of said sides representing the back of said lens.

15. The lens according to claim 7 wherein said lens body has zero or near zero refractive power.

16. The lens according to claim 7 wherein said lens body provides refractive power to said lens.

17. The lens according to claim 7 wherein said first and second diffractive structures are combined into a single diffractive structure along one of said first or second surfaces.

18. The lens according to claim 17 further comprising an optical element integrated with said lens along said one of said first and second surfaces, and said optical element provides said lens with a smooth outer surface.

19. The lens according to claim 7 wherein said lens is part of an intraocular implant.

20. The lens according to claim 7 wherein said lens represents a contact lens.

21. The lens according to claim 7 wherein said lens represents a spectacle lens.

22. The lens according to claim 7 wherein at least one of said first and second diffractive structures corrects for astigmatism.

23. The lens according to claim 7 wherein at least one of said first and second diffractive structures has refractive curvature which corrects for astigmatism.

24. The lens according to claim 7 wherein said lens body is composed of a single optical element.

25. The lens according to claim 7 wherein said lens body is composed of a plurality of optical elements integrated together.

26. The lens according to claim 7 wherein said first diffractive structure splits light energy substantially equally in each of the orders of said first diffractive structure.

27. The lens according to claim 7 wherein said first diffractive structure provides a certain amount of light into each of the orders of said first diffractive structure.

28. The lens according to claim 7 wherein said lens body is sufficiently thin for use in IOL or contact applications.

29. The lens according to claim 7 wherein said first diffractive structure splits light into two diffractive orders, and said first and second diffractive structures in combination provide a bifocal one of said lens with near and distance vision correction.

30. The lens according to claim 7 wherein said first diffractive structure splits light into three diffractive orders, and said first and second diffractive structures in combination provide a trifocal one of said lens with near, intermediate, and distance vision correction.

31. The lens according to claim 7 wherein said first diffractive structure is a diffractive structure having a plurality of zones wherein each of the zones has locations in accordance with the equation

32. The lens according to claim 7 further comprising an optical element, wherein said optical element is integrated with said one of said first and second surfaces upon which said second diffractive structure is located to provide a smooth surface.

33. The lens according to claim 32 wherein said optical element represents one of a substrate or coating.

34. A method for providing a bifocal ophthalmic lens having a base power and an add power comprising the steps of:

selecting a first diffractive structure for the lens for diffracting light in a plurality of different diffractive orders to a common focal distance or range in accordance with needed base power of the lens; and

selecting a second diffractive structure for the lens for splitting light into two or more diffractive orders to different focal distances or ranges in which the base power for distance vision correction and add power for near vision correction are in accordance with a combination of said first and said second diffractive structures, in which said second diffractive structure represents a sinusoidal harmonic diffractive structure having a plurality of zones that is continuous within each of the zones and at the boundaries between zones.

35. The method according to claim 34 wherein said second diffractive structure is a diffractive structure having a plurality of zones wherein each of the zones has locations in accordance with the equation

36. The method according to claim 34 wherein lens has first and second surfaces, and said first and second diffractive structures are located on the same or different ones of said first and second surfaces.

37. The method according to claim 34 wherein said first diffractive structure represents a multiorder diffractive structure characterized by a plurality of zones which define zone boundaries at which light incident on the diffractive structure experiences an optical phase shift, and which diffract light of each of said wavelengths in a different diffractive order, m, such that the magnitude of m≧

1, to the focal distance or range for the diffractive structure.

38. The method according to claim 34 wherein lens has first and second surfaces, and said method further comprises the step of:

adding to the surface of said lens having said second diffractive element an optical substrate providing a smooth surface.

39. The method according to claim 34 further comprising the step of:

selecting the body of said lens to have zero or approximately zero refractive power.

40. The method according to claim 34 further comprising the step of:

selecting the body of said lens to have refractive power.

41. The method according to claim 34 wherein at least one of said first and second diffractive structures corrects for astigmatism.

42. The method according to claim 34 wherein at least one of said first and second diffractive structures has refractive curvature to correct for astigmatism.

43. An optical element comprising:

a lens body having first and second surfaces;

a first diffractive structure for splitting light into two or more diffractive orders to different focal distances or ranges;

a second diffractive structure for diffracting light into a plurality of different diffractive orders to a common focal distance or range, in which said first and second diffractive structures are located on the same or different ones of said first and second surfaces; and

said first diffractive structure and said second diffractive structure in combination provide a plurality of different focal distances or ranges for vision correction at different distances or ranges, in which said first diffractive structure represents a sinusoidal harmonic diffractive structure.

44. The optical element according to claim 43 wherein said different focal distances or ranges are two to provide a bifocal lens having near and far distance correction.

45. The optical element according to claim 43 wherein said different focal distances or ranges are three to provide a trifocal lens having near, intermediate, and far distance correction.

46. An ophthalmic lens comprising a lens body having a sinusoidal harmonic diffractive structure for splitting light of different wavelengths into two or more diffractive orders to different focal distances or ranges to provide two or more different powers, and said lens body provides refractive base optical power to the lens.

47. The lens according to claim 46 wherein said lens body further comprises a multiorder diffractive structure for diffracting light into a plurality of different diffractive orders to a common focal distance or range which combines with said refractive optical power to provide the base optical power of the lens.

48. The lens according to claim 46 wherein said sinusoidal harmonic diffractive structure has a plurality of zones wherein each of the zones has locations in accordance with the equation

49. The lens according to claim 46 wherein said lens is part of one of an intraocular implant, a contact lens, or a spectacle lens multiple optical elements.

50. The lens according to claim 46 wherein said lens body is provided by a single or