Lens system and optical apparatus

Abstract

A lens system includes a first lens which is formed of a medium exhibiting negative refraction and a second lens which is formed of a medium having a positive refractive index. Abbe's number for a material which forms the first lens differs from Abbe's number for a material which forms the second lens. Moreover, a lens system includes a first lens which is formed of a medium exhibiting negative refraction and a second lens which is formed of a medium exhibiting negative refraction. Abbe's number for a material which forms the first lens differs from Abbe's number for a material which forms the second lens.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a structure of a lens system according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a relationship between an angular frequency and a refractive index;

FIG. 3 is a diagram showing a structure of a lens system according to a modified embodiment;

FIG. 4 is a diagram showing a structure of a lens system according to a second embodiment;

FIG. 5 is a diagram showing a structure of a lens system according to a third embodiment of the present invention;

FIG. 6 is a diagram showing a structure of a lens system according to another modified embodiment;

FIG. 7 is a diagram showing a first concrete example of a photonic crystal 340;

FIG. 8 is a diagram showing a second concrete example of the photonic crystal 340;

FIG. 9 is a diagram for describing an image formation by a plane-parallel plate 380 which is formed of a negative refractive index medium 301; and

FIG. 10 is a diagram for describing a chromatic aberration.

Claims

1. A lens system comprising: a first lens which is formed of a medium exhibiting negative refraction; anda second lens, whereina sign of Abbe's number for a material which forms the first lens differs from a sign of Abbe's number for a material which forms the second lens.

2. The lens system according to claim 1, wherein the second lens which is formed of a medium having a positive refractive index.

3. The lens system according to claim 1, wherein the second lens which is formed of a medium exhibiting negative refraction.

4. A lens system comprising: a first lens which is formed of a medium exhibiting negative refraction; anda second lens, whereina sign of Abbe's number for a material which forms the first lens is same as a sign of Abbe's number for a material which forms the second lens.

5. The lens system according to claim 4, the second lens which is formed of a medium having a positive refractive index.

6. The lens system according to claim 4, wherein the second lens which is formed of a medium exhibiting a negative refraction.

7. The lens system according to one of claims 1 to 3, wherein a sign of a focal length of the first lens is same as a sign of a focal length of the second lens.

8. The lens system according to claim 7, which includes the first lens and the second lens.

9. The lens system according to one of claims 1 to 3, wherein an following expression 123 is satisfied:

10. The lens system according to one of claims 4 to 6, wherein a sign of a focal length of the first lens differs from a sign of the focal length of the second length.

11. The lens system according to claim 10, which includes the first lens and the second lens.

12. The lens system according to one of claims 4 to 6, wherein an following expression 123 is satisfied:

13. An optical apparatus comprising: the lens system according to one of claims 1 to 6.

14. The lens system according to one of claims 1 to 6, wherein the medium exhibiting the negative refraction is a negative refractive index medium.

15. The lens system according to one of claims 1 to 6, wherein the medium exhibiting the negative refraction is a medium which exhibits properties of perfect imaging.

16. The lens system according to one of claims 1 to 6, wherein the medium exhibiting the negative refraction is a photonic crystal.

17. The lens system according to claim 16, wherein the photonic crystal is used as the medium exhibiting negative refraction, and an axis of the photonic crystal for which a rotational symmetry is optimum is directed toward an optical axis of the optical system.

18. The lens system according to one of claims 1 to 6, wherein the medium exhibiting negative refraction satisfies following expression 5-8: −8.0≦∈′≦−0.2  expression (5-8)where ∈′=∈/∈c ∈ is a dielectric constant of the medium of the lens, and ∈c is a dielectric constant of the medium around the lens.

19. The lens system according to one of claims 1 to 6, wherein a refractive index of the material exhibiting negative refraction satisfies following expression 142: −10≦ns≦−0.1  expression 142where ns is a refractive index of the negative refractive index medium for vacuum.

20. The lens system according to one of claims 1 to 6, wherein Abbe's number for the medium exhibiting negative refraction satisfies following expression 147: 0.01≦|ν|≦10000  expression 147where ν is Abbe's number for the medium exhibiting negative refraction.