Multifocal birefringent lens system

• US 4,981,342 A
• Filed: 08/01/1988
• Issued: 01/01/1991
• Est. Priority Date: 09/24/1987
• Status: Expired due to Fees

• Current Assignee: Werner J. Fiala
• Original Assignee: Allergan Incorporated (Abbvie Incorporated)
• Inventors: Fiala, Werner J.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Lerner, Martin
• Application Number:
  US07/226,669
• Time in Patent Office: 883 Days
• Field of Search: 350/379, 350/403, 350/405, 350/411, 350/397, 351/161, 351/164, 351/168, 351/171
• US Class Current: 359/489.18
• CPC Class Codes: A61F 2/1618 Multifocal lenses
• CPC Class Codes: A61F 2/1648 Multipart lenses
• CPC Class Codes: A61F 2002/1699 Additional features not otherwise provided for
• CPC Class Codes: G02B 3/10 Bifocal lenses; Multifocal lenses
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02C 2202/16 Laminated or compound lenses
• CPC Class Codes: G02C 2202/22 Correction of higher order and chromatic aberrations, wave front measurement and calculation
• CPC Class Codes: G02C 7/02 Lenses; Lens systems ; Methods of designing lenses
• CPC Class Codes: G02C 7/028 Special mathematical design techniques
• CPC Class Codes: G02C 7/041 bifocal; multifocal
• CPC Class Codes: G02C 7/042 Simultaneous type
• CPC Class Codes: G02C 7/049 Contact lenses having special fitting or structural features achieved by special materials or material structures
• CPC Class Codes: G02C 7/06 bifocal; multifocal ; progressive G02C7/041 takes precedence
• CPC Class Codes: G02C 7/12 Polarisers

Abstract

A multifocal birefringent lens system is described together with applications of the lens system such as ophthalmic lenses (including those of the intraocular, contact and spectacle type) and optical instruments and devices including photographic cameras, telescopes, microscopes, copiers, spectrographic instruments, etc.

Claims

1. A multifocal non-achromatized birefringent lens system which comprises:

(a) a first lens component which is a first birefringent lens possessing two positive or negative powers Do_a and De_a in which Do_a is the value of the power of the lens associated with the ordinary rays of said lens and De_a is the value of the power of the lens associated with the extraordinary rays of said lens, the ratio Do_a /De_a being determined by the indices of refraction and the orientation of the crystal optic axis of the lens; and

,

(b) a second lens component adjacent to said first lens component, the curvatures of the opposed surfaces of the first and second lens components being substantially identical or complementary, said second lens component being selected from the group consisting of

(i) a second birefringent lens possessing two different positive or negative powers Do_b and De_b in which Do_b is the value of the power of the lens associated with the ordinary rays of said lens and De_b is the value of the power of the lens associated with the extraordinary rays of said lens, the ratio Do_b /De_b being determined by the indices of refraction and the orientation of the crystal optic axis of the lens, and

(ii) an isotropic lens possessing a positive, negative, or zero power D,

provided that in the case of the lens system comprising first birefringent lens (a) and second birefringent lens (b) (i), said first birefringent lens (a) and said second birefringent lens (b) (i) are shaped and positioned such that at least two out of the four resulting powers Do_a +Do_b, Do_a +De_b, De_a +Do_b and De_a +De_b of the lens systems are selectable independently from one another, and

in the case of the lens system comprising first birefringent lens (a) and isotropic lens (b) (ii), said first birefringent lens (a) and said isotropic lens (b) (ii) are shaped and positioned such that both of the resulting powers Do_a +D and De_a +D are selectable independently from one another,

said lens system exhibiting no unwanted power or powers, and

said lens system employed as a contact lens.

2. The lens system of claim 1 wherein any one surface of first lens component (a) or second lens component (b) is given a curvature in independence of said preselected arbitrary powers and in independence of the orientation of the extraordinary rays of first birefringent lens (a) relative to the crystal optic axis of lens (a).

3. The lens system of claim 1 wherein a first lens component (b) is positioned in front of lens component (a) and a second lens component (b) is positioned behind lens component (a), any one surface of lens component (a) or either of lens components (b) being given a curvature in independence of said preselected powers and all extraordinary rays of lens component (a) being perpendicular to the crystal optic axis of lens component (a).

4. The lens system of claim 1 wherein at least one birefringent lens is fabricated from a polymeric birefringent material.

5. The lens system of claim 1 possessing three or more independently selected powers.

6. The lens system of claim 1 further comprising at least one polarizer means other than a birefringent lens and/or at least one polarizing filter.

7. The lens system of claim 6 wherein the polarizer means is positioned in front of and/or between the lens components and the polarizing filter, where present, is positioned in front of and/or in between and/or behind the lens components.

8. The lens system of claim 6 wherein at least one of the polarizer means, the birefringent lens and the polarizing filter exhibits a degree of freedom for rotation about the lens system axis.

9. A bifocal, birefringent lens system having two powers D_a and D_b which comprises

(a) a first lens component which is a birefringent lens possessing two positive or negative powers, one of which, D_2o,bl, is for ordinary rays of blue light, the other of which, D_2e,bl, is for extraordinary rays of blue light,

(b) a second lens component which is an isotropic lens exhibiting a power, D₁,bl, for blue light, and

(c) a third lens component which is an isotropic lens exhibiting a power, D₃,bl, for blue light,

said system satisfying the following equation wherein:

n'"'"'_2e,bl =n_2e,bl -1 with n_2e,bl being the extraordinary index of refraction of lens component (a) for blue light,

n'"'"'_2o,bl =n_2o,bl -1 with n_2o,bl being the ordinary index of refraction of lens component (a) for blue light,

n'"'"'_2e,r =n_2e,r -1 with n_2e,r being the extraordinary index of refraction of lens component (a) for red light,

n'"'"'₁,r =n₁,r -1 with n₁,r being the index of refraction of lens component (b) for red light,

n'"'"'₁,bl =n₁,bl -1 with n₁,bl being the index of refraction of lens component (b) for blue light,

D_a,bl and D_a,r are respective powers for blue and red light for said D_a power, and

D_b,bl is power for blue light for said D_b power, ##EQU11## wherein D_a,bl, D_a,r and D_b,bl are preselected arbitrary values.

10. The lens system of claim 9, wherein the curvature of at least one lens component is given a value such that all extraordinary rays of lens component (a) are perpendicular to the crystal optic axis of said lens component, (a).

11. The lens component of claim 9, wherein the curvatures of at least two lens components are given values such that the extraordinary rays of at least one birefringent lens component are perpendicular with the crystal optic axis of said birefringent lens component.

12. The lens system of claim 9 exhibiting no unwanted power or powers.

13. The lens system of claim 9, further comprising at least one polarizing means other than a birefringent lens and/or at least one polarizing filter.

14. The lens system of claim 13, wherein at least one of the polarizing means, the birefringent lens and the polarizing filter exhibits a degree of freedom for rotation about the lens system axis.

15. The lens system of claim 13, wherein at least one of the polarizer means, the birefringent lens and the polarizing filter exhibits a degree of freedom for rotation about the lens system axis.

16. A multifocal, birefringent lens system exhibiting at least two powers D_a and D_b, comprising

(a) a first lens component which is a birefringent lens possessing two positive or negative powers, one of which, D_2o,bl, is for ordinary rays of blue light, the other of which, D_2e,bl, is for extraordinary rays of blue light,

(b) a second lens component which is a birefringent lens possessing two positive or negative powers, one of which, D_3o,bl, is for ordinary rays of blue light, the other of which D_3e,bl, is for extraordinary rays of blue light,

(c) a third lens component which is an isotropic lens exhibiting a power, D₁,bl, for blue light, and

(d) a fourth lens component which is an isotropic lens exhibiting a power, D₄,bl, for blue light,

said system satisfying the following equation wherein n'"'"'_2o,r =n_2o,r -1 with n_2o,r being the ordinary index of refraction of lens component (a) for red light,

n'"'"'_2o,bl =n_2o,bl -1 with n_2o,bl being the ordinary index of refraction of lens component (a) for blue light,

n'"'"'_2e,bl =n_2e,bl -1 with n_2e,bl being the extraordinary index of refraction of lens component (a) for blue light,

n'"'"'_2e,r =n_2e,r -1 with n_2e,r being extraordinary index of refraction of lens component (a) for red light,

n'"'"'_3e,bl =n_3e,bl -1 with n_3e,bl being the extraordinary index of refraction of lens component (b) for blue light,

n'"'"'_3o,bl =n_3o,bl -1 with n_3o,bl being the ordinary index of refraction of lens, component (b) for blue light,

n'"'"'_3e,r =n_3e,r -1 with n_3e,r being the extraordinary index of refraction of lens component (b) for red light,

n'"'"'_3o,r =n_3o,r -1 with n_3o,r being the ordinary index of refraction of lens component (b) for red light,

n'"'"'₁,r =n₁,r -1 with n₁,r being the index of refraction of lens component (c) for red light,

n'"'"'₁,bl =n₁,bl -1 with n₁,bl being the index of refraction of lens component (c) for blue light,

n'"'"'₄,r =n₄,r -1 with n₄,r being the index of refraction of lens component (d) for red light,

n'"'"'₄,bl =n₄,bl -1 with n₄,bl being the index of refraction of lens component (d) for blue light,

D_a,bl and D_a,r are respective powers for blue and red light for said D_a power, and

D_b,bl and D_b,r are respective powers for blue and red light for said D_b power, ##EQU12## wherein D_a,bl, D_a,r, D_b,bl and D_b,r are preselected arbitrary values.

17. The lens system of claim 16, wherein the curvature of at least one lens component is given a value such that all extraordinary rays of lens component (a) are perpendicular to the crystal optic axis of said lens component (a).

18. The lens component of claim 16, wherein the curvature of at least two lens components are given values such that the extraordinary rays of at least one birefringent lens component are perpendicular with the crystal optic axis of said birefringent lens component.

19. The lens system of claim 16 exhibiting no unwanted power or powers.

20. The lens system of claim 16, further comprising at least one polarizer means other than a birefringent lens and/or at least one polarizing filter.