Refractive index gradient lens

• US 5,861,934 A
• Filed: 05/06/1996
• Issued: 01/19/1999
• Est. Priority Date: 05/06/1996
• Status: Expired due to Fees

• Current Assignee: Essilor International SA (EssilorLuxottica SA)
• Original Assignee: Innotech, Inc. (Bimeda Holdings Ltd.)
• Inventors: Blum, Ronald D., Gupta, Amitava
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US08/643,656
• Time in Patent Office: 988 Days
• Field of Search: 359/652, 359/653, 359/654, 351/159, 351/168, 351/169, 351/170, 351/171, 351/172, 351/177, 264/2.7
• US Class Current: 351/169
• CPC Class Codes: B29D 11/00355 with a refractive index gradient
• CPC Class Codes: B29D 11/0073 Optical laminates
• CPC Class Codes: G02C 2202/12 Locally varying refractive index, gradient index lenses
• CPC Class Codes: G02C 2202/16 Laminated or compound lenses
• CPC Class Codes: G02C 7/061 Spectacle lenses with progressively varying focal power

Abstract

An optical product such as an optical lens, or semi-finished lens blank is provided comprising a composite of at least three different and separately applied layers, each layer having a different refractive index which allow for a progressive multifocal lens having a wide and natural progression of vision when looking from far to near. In addition, a method is provided for simply, quickly and inexpensively manufacturing a composite refractive gradient progressive multifocal lens. A transition zone disposed between a base and an outer layer includes a distinct and separately applied transition layer or layers having an effective refractive index which is intermediate between the refractive indices of the base and outer layers, and preferably approximates the geometric mean of the refractive indices of the base and outer layers. This transition zone may include multiple transition layers, with each transition layer having a different and distinct refractive index. The lens is substantially free of unwanted peripheral astigmatism, incorporates a wide reading zone and is easy to fit a patient and possesses a cosmetic appearance which is mostly invisible.

Claims

1. An optical product, comprising:

a base layer having a first refractive index and a region of varying thickness;

an outer layer having a second refractive index different from the first refractive index; and

a transition zone comprising at least one layer bonded between the base and outer layer, each of the layers having a different refractive index and which differs from the refractive indices of the base layer and the outer layer wherein the refractive index of each of said at least one layer is substantially constant throughout the layer and the transition zone has an effective refractive index which is approximately the geometric mean of the refractive indices of the base and outer layer.

2. The optical product of claim 1, wherein a surface depression is on a convex surface of the base layer and approximately defines a progressive multifocal zone.

3. The optical product of claim 2, wherein the second refractive index of the outer layer is greater than the first refractive index of the base layer.

4. The optical product of claim 3, wherein the first refractive index of the base layer is approximately 1.44 to 1.56.

5. The optical product of claim 4, wherein the second refractive index of the outer layer is approximately 1.56 to 1.70.

6. The optical product of claim 5, wherein the first refractive index of the base layer is approximately 1.49.

7. The optical product of claim 6, wherein the second refractive index of the outer layer is approximately 1.66.

8. The optical product of claim 1, wherein a raised region is on a convex surface of the base layer and approximately defines a progressive multifocal zone.

9. A composite ophthalmic lens, comprising:

an optical preform having first refractive index and a region of varying thickness;

an outer layer having a second refractive index different from the refractive index of the optical preform; and

a transition zone comprising at least one layer bonded between the optical preform and outer layer covering at least the region of varying thickness, wherein each of the at least one layer has a different refractive index and which differs from the refractive indices of the optical preform and the outer layer, the refractive index of each of the at least one layer being substantially constant throughout the layer and the transition zone having an effective refractive index approximately the geometric mean of the refractive indices of the optical preform and the outer layer.

10. The ophthalmic lens of claim 9, wherein a surface depression is on a convex surface of the optical preform and approximately defines a progressive multifocal zone.

11. The ophthalmic lens of claim 10, wherein the second refractive index of the outer layer is greater than the first refractive index of the optical preform.

12. The ophthalmic lens of claim 11, wherein the first refractive index of the optical preform is approximately 1.44 to 1.56.

13. The ophthalmic lens of claim 12, wherein the second refractive index of the outer layer is approximately 1.56 to 1.70.

14. The ophthalmic lens of claim 13, wherein the first refractive index of the optical preform is approximately 1.49.

15. The ophthalmic lens of claim 14, wherein the second refractive index of the outer layer is approximately 1.66.

16. The ophthalmic lens of claim 9, wherein a raised region is on a convex surface of the optical preform and approximately defines a progressive multifocal zone.

17. A method of manufacturing a composite optical product, comprising the steps of

a.) providing a base layer having a first refractive index and a surface depression;

b.) applying a transition zone comprising at least one resin layer to at least the surface depression of the base layer, the transition zone having an effective refractive index that is approximately the geometric mean of the refractive indices of the base layer and the outer layer, wherein each of said at least one layer having a different refractive index which is substantially constant throughout the layer and which differs from the refractive indices of the base layer and outer layer, and each of the at least one layer is at least partially cured before application of a subsequent layer;

c.) applying an outer layer of resin to at least the transition zone, the outer layer having a second refractive index different from the refractive index of the base layer; and

d.) curing the transition zone and the outer layer to produce a finished optical product.

18. The method of claim 17 further comprising the step of molding the outer layer to a desired curvature.

19. The method of claim 18, wherein the outer layer is a partially cured polymeric layer.

20. The method of claim 17, further comprising the step of partially curing the transition zone before applying the outer layer.

21. The method of claim 18, wherein the transition zone is partially cured using light having a wavelength of approximately 250-450 nm.

22. The method of claim 21, wherein the transition zone is partially cured using visible light having a wavelength of approximately 400-450 nm.

23. The method of claim 17, wherein the outer layer is applied to the transition layer by surface casting.

24. The method of claim 17, further comprising the step of applying at least one resin layer between the base layer and the outer layer.

25. The method of claim 17, wherein said transition layer is provided by brushing, spin coating, dip coating, or spray coating.

26. A composite ophthalmic lens, comprising:

an optical preform having a refractive index of approximately 1.49 and a surface depression on a convex surface of the optical preform, the surface depression approximately defining a progressive multifocal zone, said optical preform having a spherical power or an astigmatic power of both;

an outer plastic layer having a refractive index of approximately 1.66; and

a transition zone comprising at least one layer bonded between the optical preform and outer layer covering at least the surface depression, wherein each of the at least one layer has a different refractive index which differs from the refractive indices of the optical preform and the outer layer, said refractive index of each of the at least one layer being substantially constant throughout the layer, and the transition zone having an effective refractive index which is approximately the geometric mean of the refractive indices of the optical preform and the outer layer.

27. A method of manufacturing a composite optical product, comprising the steps of:

a.) providing a base layer having a first refractive index and a surface having a raised region;

b.) applying a transition zone comprising at least one layer of resin to at least the raised region of the base layer, the transition zone having an effective refractive index which is the geometric mean of the refractive indices of the base layer and an outer layer, wherein the each of said at least one layer comprising resin and having a different refractive index which is substantially constant throughout the layer and which differs from the refractive indices of the base layer and an outer layer, and each of the at least one layer is at least partially cured before application of a subsequent layer;

c.) applying an outer layer of resin to at least the transition zone the outer layer having a second refractive index different from the refractive index of the base layer and the effective refractive index of the transition zone; and

d.) curing the transition zone and outer layer to produce a finished optical product.

28. A composite ophthalmic lens, comprising:

an optical preform having a refractive index of approximately 1.49 and a raised region on a convex surface of the optical preform, the raised region approximately defining a progressive multifocal zone, said optical preform having a spherical power or an astigmatic power of both;

an outer plastic layer having a refractive index of approximately 1.66; and

a transition zone comprising at least one layer bonded between the optical preform and outer layer covering at least the surface depression, wherein each of the at least one layer has a different refractive index and which differs from the refractive indices of the optical preform and the outer layer, said refractive index of each of the at least one layer being substantially constant throughout the layer, and the transition zone having an effective refractive index which is approximately the geometric mean of the refractive indices of the optical preform and the outer layer.