ANAMORPHIC LENS SYSTEM

• US 3,749,477 A
• Filed: 08/16/1971
• Issued: 07/31/1973
• Est. Priority Date: 08/16/1971
• Status: Expired due to Term

• Current Assignee: Barry G. Broome, John H. Willoughby
• Original Assignee: Barry G. Broome, John H. Willoughby
• Inventors: Willoughby, John H., Broome, Barry G.
• Primary Examiner(s): Corbin, John K.
• Application Number:
  US05/171,942
• Time in Patent Office: 715 Days
• Field of Search: 350/181,190,212
• US Class Current: 359/671
• CPC Class Codes: G02B 13/08 Anamorphotic objectives

Abstract

An anamorphic lens system is disclosed for attachment to cameras having low effective aperture prime lenses. The lens system comprises a plurality of plastic lens elements having a low dispersion property. The lens elements are characterized in that the aberration introduced by one or more elements in the positive sense is matched by one or more elements in the negative sense. These capabilities enable the lens system to be manufactured more economically, while still having a high degree of aberration control.

Claims

1. A plastic anamorphic cylindrical lens system for providing an increased angular field of view resulting from a different magnification of image rays in each of two perpendicular directions comprising:

a first diverging group of plastic cylindrical lens elements aligned to have a power plane in one direction and a traverse non-power plane in another direction, at least one cylindrical lens element introducing negative cylindrical oblique ray aberrations in both the power plane and the non-power plane and a second plastic converging cylindrical lens element introducing positive cylindrical oblique ray aberrations to apply a concurrent correction in both the power plane and the non-power plane of the oblique ray aberrations, the plastic of each lens having a low dispersion factor and approximately the same index of refraction.

2. The invention of claim 1 wherein said plastic material is methyl methacrylate.

3. The invention of claim 2 wherein said elements are shaped and grouped to introduce a relatively small amount of bending to a fan of rays at any chosen object point.

4. The invention of claim 1 wherein said elements comprise four elements poisitioned along an optical axis, the first three elements forming a group which diverges the fan of rays entering the first element to introduce a net amount of negative cylindrical oblique aberration, the fourth element converging the fan of rays in a manner to introduce a net amount of positive cylindrical oblique aberration which matches the aberration produced by the first three elements.

5. The combination of claim 1 where the focal length of the plastic lens system is short enough to prevent significant chromatic aberrations.

6. A plastic anamorphic cylindrical lens system adapted for attachment to cameras having low effective aperture prime lenses to provide an increased angular field of view resulting from a different magnification of image rays in each of two perpendicular directions comprising:

a first diverging group of plastic cylindrical lens elements aligned to have a power plane in one direction and a traverse non-power plane in another direction, at least one cylindrical lens element introducing negative cylindrical oblique ray aberrations in both the power plane and the non-power plane and a second plastic converging cylindrical lens element introducing positive cylindrical oblique ray aberrations to apply a concurrent correction in both the power plane and the non-power plane of the oblique ray aberrations, all of the lenses in the system consisting of only methyl methacrylate.

7. A plastic anamrophic cylindrical lens system adapted for attachment to cameras having low effective aperture prime lenses to provide an increased angular field of view resulting from a different magnification of image rays in each of two perpendicular directions comprising:

a first group of three plastic cylindrical lens elements aligned to have a power plane in one direction and a traverse non-power plane in another direction, the three elements forming a group which diverges the fan of rays entering the first element to introduce a net amount of negative cylindrical oblique aberration, in both the power plane and the non-power plane and a second plastic cylindrical lens element introducing a net amount oF positive cylindrical oblique aberration which matches the aberration produced by the first three elements to apply a concurrent correction in both the power plane and the non-power plane of the oblique ray aberrations, all of the lenses in the system consisting of only plastic material.

8. The invention of claim 7 wherein each element is made from a plastic material having a low dispersion property.

9. The invention of claim 8 wherein said plastic material is methyl methacrylate.

10. The invention of claim 9 wherein said elements are shaped and grouped to introduce a relative small amount of bending to a fan of rays at any chosen object point.

11. The invention of claim 7 wherein the first element comprises a lens having a convex cylindrical surface having a radius of 1.2541 inches and a concave cylindrical surface having a radius of 0.5000 inches.

12. The invention of claim 11 wherein said seond element comprises a lens having a first convex cylindrical surface having a radius of 4.0000 inches, said first surface facing the concave surface of said first element, said second element further having a second convex cylindrical surface having a radius of 1.2330 inches.

13. The invention of claim 12 wherein said third element comprises a lens having a first concave cylindrical surface having a radius of 0.8225 inches, said first concave surface facing the second convex surface of said second element, said third element having a second concave cylindrical surface having a radius of 0.7400 inches.

14. The invention of claim 13 wherein said fourth element comprises a lens having a planar surface facing the second surface of said third element and a convex surface having a radius of 0.6335 inches.

15. The inventioof claim 12 wherein the airspace between the first two elements at the optic axis is 0.3034 inches.

16. The invention of claim 13 wherein the airspace between the second and third elements at the optic axis is 0.0837 inches.

17. The invention of claim 14 wherein the airspace between the third and fourth elements at the optic axis is 0.3250 inches.

18. The invention of claim 11 wherein the thickness of the first element along the optic axis is 0.2500 inches.

19. The invention of claim 12 wherein the thickness of the second element along the optic axis is 0.2550 inches.

20. The invention of claim 13 wherein the thickness of the third element along the optic axis is 0.0600 inches.

21. The invention of claim 14 wherein the thickness of the fourth element along the optic axis is 0.1850 inches.

22. The invention of claim 7 wherein the index of refraction for each of the elements is 1.4920.