One optical design pattern/method of a cost effective IR lens

Abstract

An optical design pattern/method was invented to control the total cost including the material and the manufacturing of IR imaging lenses. This optical design pattern/method comprises a molded lens and an aberration correction lens. This design pattern/method leads to cost-effective IR imaging lenses because the unit cost of the molded lens is low for a volume production and the unit cost of the aberration correction lens is low for its very small manufacturing. This optical design pattern/method comprises any imaging and spectral applications for any partial band of 1 to 14 micron, such as (but not limited to) SWIR, MWIR, and LWIR.

Claims

1. A lens system comprising: a first lens element having a first and second surface, one of the first and second surfaces being a concave surface and the other of the first and second surfaces being a convex surface, and one of the first and second surfaces of the first lens element being a diffractive surface, the first lens element comprising chalcogenide glass, and a second lens element having a planar surface and no diffractive surfaces, the second lens element comprising a material selected from the group consisting of Germanium, Silicon, ZnSe, ZnS, CdTe, KBr, CaF2, BaF2, MgF2, SiO2, and GaAs, wherein the optical power of the first lens element is greater than the optical power of the second lens element, and wherein the second lens element provides aberration correction.

2. The lens system of claim 1, wherein the focal length of the lens system is about 22.5 mm.

3. The lens system of claim 1, wherein the second lens element comprises an aspheric surface opposite the planar surface.

4. The lens system of claim 1, wherein the first lens element comprises an aspheric surface.

5. The lens system of claim 1, wherein the first lens element comprises a spherical surface.

6. An imaging system comprising the lens system of claim 1, the imaging system comprising a focal plane array (FPA), wherein the second lens element is between the first lens element and FPA, the lens system configured to direct light incident on the first lens element in a wavelength range between 1 to 14 micron on the FPA.

7. The lens system of claim 6, wherein the lens system has no other lens elements positioned between the first lens element and the second lens element.

8. The lens system of claim 7, wherein there are no other lens elements positioned between the second lens element and the FPA.

9. An imaging system comprising the lens system of claim 1, the imaging system comprising a focal plane array (FPA), wherein the first lens element is between the second lens element and FPA, the lens system configured to direct light incident on the second lens element in a wavelength range between 1 to 14 micron on the FPA.

10. The lens system of claim 9, wherein there are no other lens elements positioned between the second lens element and the FPA.

11. The lens system of claim 10, wherein there are no other lens elements positioned between the first lens element and the second lens element.

12. A lens assembly comprising: a first lens element comprising chalcogenide glass, the first lens element having a first and second surface, one of the first and second surfaces being a concave surface and the other of the first and second surfaces being a convex surface, one of the first and second surfaces of the first lens element being a diffractive surface; and a second lens element having a planar surface and no diffractive surfaces, the second lens element comprising a material selected from the group consisting of Germanium, Silicon, ZnSe, ZnS, CdTe, KBr, CaF2, BaF2, MgF2, SiO2, and GaAs, wherein the optical power of the second lens element is less than the optical power of the first lens element, and wherein the second lens element provides aberration correction.

13. The lens assembly of claim 12, wherein the second lens element comprises an aspheric surface opposite the planar surface.

14. The lens assembly of claim 12, wherein the first lens element comprises an aspheric surface.

15. The lens assembly of claim 12, wherein the first lens element comprises a spherical surface.

16. The optical system of claim 12, wherein the lens assembly has no other lens elements positioned between the first lens element and the second lens element.

17. An optical system comprising: a molded lens having an optical power, the molded lens having a first and second surface, one of the first and second surfaces being a concave surface and the other of the first and second surfaces being a convex surface, and one of the first and second surfaces of the first lens element being a diffractive surface, the molded lens comprising chalcogenide glass, and an aberration correction element having no diffractive surfaces, the aberration correction element comprising a material selected from the group consisting of Germanium, Silicon, ZnSe, ZnS, CdTe, KBr, CaF2, BaF2, MgF2, SiO2, and GaAs, wherein optical power provided by the aberration correction element is less than the optical power of the molded lens, and wherein the aberration correction element comprises a planar surface.

18. The optical system of claim 17, wherein the aberration correction element comprises an aspheric surface opposite the planar surface.

19. The optical system of claim 17, wherein the molded lens comprises an aspheric surface.

20. The optical system of claim 17, wherein the molded lens comprises a spherical surface.

21. The optical system of claim 17, wherein the optical system has no other lens elements positioned between the molded lens and the aberration correction element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following figures are intended only to further illustrate the invention and are not intended to limit the scope of the invention which is defined by the claims.

(2) FIG. 1 is one kind of optical configuration of this kind of optical design pattern/method with a front aberration correction lens and a back molded lens with one aspheric+diffractive surface.

(3) FIG. 2 is one kind of optical configuration of this kind of optical design pattern/method with a front aberration correction lens and a back molded lens with one aspheric+diffractive surface.

(4) FIG. 3 is one kind of optical configuration of this kind of optical design pattern/method with a back aberration correction lens and a front molded lens with one aspheric+diffractive surface.

(5) FIG. 4 is one kind of optical configuration of this kind of optical design pattern/method with a back aberration correction lens and a front molded lens with one aspheric+diffractive surface.

(6) FIG. 5 is one kind of optical configuration of this kind of optical design pattern/method with a front aberration correction lens and a back molded lens with one aspheric+diffractive surface.

(7) FIG. 6 is one kind of optical configuration of this kind of optical design pattern/method with a front aberration correction lens and a back molded lens with one aspheric+diffractive surface.

(8) FIG. 7 is one kind of optical configuration of this kind of optical design pattern/method with a back aberration correction lens and a front molded lens with one aspheric+diffractive surface.

(9) FIG. 8 is one kind of optical configuration of this kind of optical design pattern/method with a back aberration correction lens and a front molded lens with one aspheric+diffractive surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(10) The embodiments described herein can be implemented by integrating a cost effective molded lens and a cost effective aberration correction lens.

(11) The molded lens is a molded chalcogenide glass lens that has an optical power that is almost same as the optical power of the whole lens assembly.

(12) The aberration correction lens is a low-cost lens that is primarily for the consideration of the aberration correction of the molded lens. This lens has a small manufacturing requirement to control its cost.

(13) The following examples are intended only to further illustrate the invention and are not intended to limit the scope of the invention which is defined by the claims.

(14) Referring to FIG. 1, the front aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA (Focal Plane Array), 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is an aspheric surface, surface 5 is a planar surface, surface 6 is a spherical surface, and surface 7 is an aspheric+diffractive surface.

(15) Referring to FIG. 2, the front aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is a planar surface, surface 5 is an aspheric surface, surface 6 is a spherical surface, and surface 7 is an aspheric+diffractive surface.

(16) Referring to FIG. 3, the back aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is an aspheric+diffractive surface, surface 5 is a spherical surface, surface 6 is a planar surface, and surface 7 is an aspheric surface.

(17) Referring to FIG. 4, the back aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is an aspheric+diffractive surface, surface 5 is a spherical surface, surface 6 is an aspheric surface, and surface 7 is a planar surface.

(18) Referring to FIG. 5, the front aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is an aspheric surface, surface 5 is a planar surface, surface 6 is an aspheric+diffractive surface, and surface 7 is a spherical surface.

(19) Referring to FIG. 6, the front aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is a planar surface, surface 5 is an aspheric surface, surface 6 is an aspheric+diffractive surface, and surface 7 is a spherical surface.

(20) Referring to FIG. 7, the back aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 is a spherical surface, surface 5 is an aspherical+diffractive surface, surface 6 is a planar surface, and surface 7 is an aspheric surface.

(21) Referring to FIG. 8, the back aberration correction lens has an aspheric surface and a planar surface. Here, 1 is the front element, 2 is the back element, 3 is the FPA, 4 is the front surface of the front element, 5 is the back surface of the front element, 6 is the front surface of the back element, and 7 is the back surface of the back element. In this optical configuration, surface 4 a spherical surface, surface 5 is an aspheric+diffractive surface, surface 6 is an aspheric surface, and surface 7 is a planar surface.

Example 1

(22) A lens sample was shown here. This lens is an optically a-thermalized lens for the wavelength range from 8-12 micron. The focal length, F #, and the angular FOV (Field of View) of it are 22.5 mm, 1.4, and 22.6, respectively.

(23) 1. The first optical element is an aberration correction lens with the following features/specifications/parameters. a. The material of it is Germanium. b. The first surface is an aspheric surface with maximum sag of 23 micron. c. The second surface is a planar surface.

(24) 2. The second optical element is a molded lens with the following features/specifications/parameters. a. The material of it is one kind of chalcogenide glass, As.sub.40Se.sub.60. b. The first surface is a concave spherical surface. c. The second surface is a convex aspheric+diffractive surface.

(25) Both the molded lens and the aberration correction are cost-effective. The total cost including the material and the manufacturing is significantly lower than the conventional lenses of the same optical performance and specifications for volume production.