DUAL FOCAL LENGTH LENS SYSTEM

• US 20090135502A1
• Filed: 11/27/2007
• Published: 05/28/2009
• Est. Priority Date: 11/27/2007
• Status: Active Grant

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Eastman Kodak Company
• Inventors: Bietry, Joseph R., Border, John N., Cahall, Scott C., Griffith, John D.
• Granted Patent: US 7,764,440 B2
• Time in Patent Office: Days
• US Class Current: 359/721
• CPC Class Codes: G02B 17/0896 with variable magnification or multiple imaging planes, including multispectral systems systems with only refractive elements G02B15/14

Abstract

A dual focal length optical system includes a first optical system and a second optical system. The first optical system is positioned along an optical axis and includes an optical structure having an object side surface and an image side surface. The object side surface and the image side surface include a refractive surface portion and a reflective surface portion. The first optical system has a focal length. The second optical system is positioned on the same optical axis and has a focal length. The focal length of the first optical system is longer than the focal length of the second optical system.

Claims

1. A dual focal length optical system comprising:

a first optical system positioned along an optical axis, the first optical system including an optical structure having an object side surface and an image side surface, the object side surface and the image side surface including a refractive surface portion and a reflective surface portion, the first optical system having a focal length; and

a second optical system positioned on the same optical axis, the second optical system having a focal length, the focal length of the first optical system being longer than the focal length of the second optical system.

2. The system of claim 1, wherein the reflective surface portion of the image side surface of the optical structure has optical power.

3. The system of claim 2, the refractive surface portion of the object side surface of the optical structure having optical power, wherein the optical power of the object side surface of the optical structure is less than the optical power of the image side surface of the optical structure.

4. The system of claim 2, wherein the image side surface of the optical structure includes an aspheric surface.

5. The lens system of claim 1, wherein the refractive surface portion of the object side surface of the optical structure has optical power.

6. The system of claim 5, wherein the object side surface of the optical structure includes an aspheric surface.

7. The system of claim 1, wherein the object side surface and the image side surface of the optical structure of the first optical system make up portions of the same optical element.

8. The system of claim 7, wherein the optical element is a solid material element.

9. The system of claim 8, wherein the solid material element comprises two elements cemented together.

10. The system of claim 1, further comprising:

a first image sensor associated with the first optical system; and

a second image sensor associated with the second optical system.

11. The system of claim 10, further comprising:

an additional optical element positioned between the first image sensor and the first optical system.

12. The system of claim 11, wherein the additional optical element is moveable positioned in order to affect a change in focal length, focus, or both.

13. The system of claim 10, wherein one or both of the first image sensor and the second image sensor is moveable along its associated optical path to affect a change in focus.

14. The system of claim 10, further comprising:

a controller configured to perform a digital zooming function using both the images produced by the first optical system and the second optical system.

15. The system of claim 1, the refractive surface portion of the object side surface of the optical structure having a first refractive surface portion and a second refractive surface portion, wherein the first refractive surface portion is associated with the first optical system and the second refractive surface portion is associated with the second optical system.

16. The system of claim 15, wherein the first refractive surface portion and the second refractive surface portion of the object side surface of the optical structure form a continuous surface.

17. The system of claim 16, wherein the first refractive surface portion and the second refractive surface portion of the object side surface of the optical structure have the same radius of curvature.

18. The system of claim 15, further comprising:

a first image sensor associated with the first optical system; and

a second image sensor associated with the second optical system.

19. The system of claim 10, further comprising:

an additional optical element positioned between the second image sensor and the second refractive surface portion of the optical structure.

20. The system of claim 19, wherein the additional optical element is moveable positioned in order to affect a change in focal length, focus, or both.

21. The system of claim 1, wherein at least one of the focal length of the first optical system and the focal length of the second optical system is a fixed focal length.