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

Abstract

A lens system for infrared (IR) imaging, including a molded first lens element and an aberration correction second lens element. The first lens element is made of chalcogenide glass and has a first and second surface, one of the first and second surfaces of the first lens element being a diffractive surface. The second lens element has a first and second surface, one of the first and second surfaces being a planar surface and neither of the first and second surfaces being a diffractive surface. The second lens element is of a different material than the second lens element.

Claims

1. A lens system for infrared (IR) imaging, comprising: a molded first lens element comprising chalcogenide glass and having a first and second surface, one of the first and second surfaces of the first lens element being a diffractive surface, and an aberration correction second lens element having a first and second surface, one of the first and second surfaces being a planar surface and neither of the first and second surfaces being a diffractive surface, 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, and the optical power of the first lens element being greater than the optical power of the second lens element, wherein the aberration correction second lens element corrects for aberration in light output by the molded first lens element.

2. The lens system of claim 1, wherein the second lens element comprises Germanium.

3. The lens system of claim 1, wherein the second lens element comprises Silicon.

4. The lens system of claim 1 wherein the second lens element comprises a material selected from the group consisting of ZnSe and ZnS.

5. The lens system of claim 1, wherein the second lens element comprises a material selected from the group consisting of CdTe, KBr, CaF2, BaF2, and MgF2.

6. The lens system of claim 1, wherein the second lens element comprises SiO2.

7. The lens system of claim 1, wherein the second lens element comprises GaAs.

8. The lens system of claim 1, wherein the optical power of the first lens element is almost the same as the optical power of the lens system.

9. The lens system of claim 1, wherein one of the first and second surfaces of the first lens element comprises a concave surface and the other of the first and second surfaces of the first lens element comprises a convex surface.

10. The lens system of claim 9, wherein the first surface of the first lens element is an aspherical diffractive surface.

11. The lens system of claim 9, wherein the second surface of the first lens element is an aspherical diffractive surface.

12. The lens system of claim 9, wherein the first surface of the first lens element is a spherical surface.

13. The lens system of claim 9, wherein the second surface of the first lens element is a spherical surface.

14. The lens system of claim 1, further 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 FPA in a wavelength range between 1 to 14 microns.

15. The lens system of claim 1, further 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 FPA in a wavelength range between 1 to 14 microns.

16. The lens system of claim 1, wherein the second lens element comprises an aspherical surface with a maximum sag of 23 microns.

17. The lens system of claim 16, wherein the first and second lens elements are configured to direct light in a wavelength range of 8-12 microns.

18. The lens system of claim 16, wherein the second lens element comprises Germanium.

19. The lens system of claim 16, wherein the first lens element comprises a concave spherical surface.

20. The lens system of claim 19, wherein the first lens element comprises a convex aspherical and a diffractive on the second surface.

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.