Lens focusing device, system and method for use with multiple light wavelengths

• US 6,750,435 B2
• Filed: 09/21/2001
• Issued: 06/15/2004
• Est. Priority Date: 09/22/2000
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Ford, Gordon D.
• Primary Examiner(s): DANG, HUNG XUAN
• Application Number:
  US09/960,629
• Publication Number:
  US 20020159165A1
• Time in Patent Office: 998 Days
• Field of Search: 250/201.2, 250/201.1, 359/210
• US Class Current: 250/201.2
• CPC Class Codes: G02B 13/146 with corrections for use in multiple wavelength bands, such as infrared and visible light, e.g. FLIR systems
• CPC Class Codes: G02B 3/10 Bifocal lenses; Multifocal lenses
• CPC Class Codes: G02B 7/04 with mechanism for focusing or varying magnification
• CPC Class Codes: G02B 7/16 Rotatable turrets

Abstract

A lens focusing system provides a lens in an optical path between a scene and a photosensitive detector to properly focus a first set of wavelengths of light. At least one representation of the scene is captured. The focal point is adjusted for a second different set of wavelengths of light. This focal adjustment may be made by moving the lens and/or the detector, offsetting the position of the lens from the first position by a predetermined amount. An alternative method would impose at least a second lens in the optical path, thereby providing focus for a different wavelength. This alternative system may include various combinations of fixed and movable lenses. At least one representation of the image is captured using this different set of wavelengths of light. The different sets of wavelengths of light can include infrared light, visible light, and subsets and combinations thereof. In at least one embodiment, one of the recorded representations is an infrared defect map that can be combined with visible light representations to form an improved image.

Claims

1. A method of focusing separate wavelengths of light from a scene, the method comprising:

focusing a first set of wavelengths of light onto a detector, wherein focusing the first set of wavelengths comprises positioning at least one lens a first distance from at least one detector; and

focusing a second set of wavelengths of light onto the at least one detector, the second set of wavelengths being different from the first set of wavelengths, and wherein focusing the second set of wavelengths comprises positioning the at least one lens a second distance from the at least one detector.

2. The method as in claim 1, wherein the second set of wavelengths of light comprises predominantly infrared light.

3. The method as in claim 1, wherein the at least one lens is positioned using a stepper motor, and wherein the second distance is a predetermined number of steps from the first distance.

4. The method as in claim 1, wherein:

the first distance from the at least one detector is determined using an automatic focusing system capable of focusing a set of wavelengths comprising visible light; and

wherein

the second distance from the at least one detector is a predetermined offset from the first distance.

5. The method as in claim 1, wherein the method is implemented in a scanner.

6. A lens focusing system comprising at least one lens capable of focusing at least two different sets of wavelengths of light from a scene onto a detector by altering the distance from said at least one lens to said detector.

7. The lens focusing system as in claim 6, wherein:

one of said at least two different sets of wavelengths of light comprises primarily visible light; and

wherein

another of said at least two different sets of wavelengths of light comprises primarily infrared light.

8. The lens focusing system as in claim 7, further comprising a motor capable of altering said distance from said at least one lens to said detector.

9. The lens focusing system as in claim 8, wherein said motor is capable of moving said at least one lens to alter said distance from said at least one lens to said detector.

10. The lens focusing system as in claim 8, wherein said motor is capable of moving said detector to alter said distance from said at least one lens to said detector.

11. The lens focusing system as in claim 8, wherein said motor is a stepper motor capable of being stepped a predetermined number of times to alter said distance from said at least one lens to said detector.

12. The lens focusing system as in claim 6, wherein:

a first distance from said at least one lens to said detector is determined using an automatic focusing system, said first distance capable of focusing a first set of wavelengths of light; and

wherein

a second distance from said at least one lens to said detector is a predetermined offset from said first distance determined using said automatic focusing system.

13. The lens focusing system as in claim 6, wherein said lens focusing system is implemented in a scanner.

14. An image capturing system comprising:

at least one illumination source capable of providing illumination in the infrared portion of the electromagnetic radiation spectrum;

at least one illumination source capable of providing illumination in the visible portion of the electromagnetic radiation spectrum;

a detector capable of generating electrical signals in response to light; and

a lens focusing system comprising at least one lens capable of focusing at least two different sets of wavelengths of light from a scene onto said detector by altering the distance from said at least one lens to said detector.

15. The image capturing system as in claim 14, wherein:

one of said at least two different sets of wavelengths of light comprises primarily visible light; and

wherein

another of said at least two different sets of wavelengths of light comprises primarily infrared light.

16. The image capturing system as in claim 14, further comprising a motor capable of altering said distance from said at least one lens to said detector.

17. The image capturing system as in claim 16, wherein said motor is capable of moving said at least one lens to alter said distance from said at least one lens to said detector.

18. The image capturing system as in claim 16, wherein said motor is capable of moving said detector to alter said distance from said at least one lens to said at least one detector.

19. The image capturing system as in claim 16, wherein said motor is a stepper motor capable of being stepped a predetermined number of times to alter said distance from said at least one lens to said detector.

20. The image capturing system as in claim 14, wherein:

a first distance from said at least one lens to said detector is determined using an automatic focusing system, said first distance capable of focusing a first set of wavelengths of light; and

wherein

a second distance from said at least one lens to said detector is a predetermined offset from said first distance determined using said automatic focusing system.

21. The image capturing system as in claim 14, wherein said image capturing system is a scanner.

22. A method of focusing separate wavelengths of light from a scene, the method comprising:

focusing a first set of wavelengths of light onto a detector, the first set of wavelengths of light comprising predominantly visible light;

focusing a second set of wavelengths of light onto the detector, the second set of wavelengths of light comprising predominantly infrared light;

wherein the step of focusing the first set of wavelengths of light comprises interposing a first lens combination in an optical path between the physical medium and the detector; and

wherein the step of focusing the second set of wavelengths of light comprises interposing a second lens combination in the optical path between the physical medium and the detector, the second lens combination being different from the first lens combination.

23. The method as in claim 22, wherein interposing a first lens combination comprises maintaining a stationary lens in the optical path of light traveling from a scene to the detector.

24. The method as in claim 23, wherein interposing a second lens combination comprises positioning at least one movable lens, in addition to the stationary lens, in the optical path of light traveling from a scene to the detector.

25. The method as in claim 23, wherein interposing a first lens combination further comprises positioning at least a first movable lens, in addition to the stationary lens, in the optical path of light traveling from a scene to the detector.

26. The method as in claim 25, wherein interposing a second lens combination comprises removing the at least a first movable lens from the optical path of light traveling from a scene to the detector, and positioning at least a second movable lens into the optical path of light traveling from a scene to the detector.

27. The method as in claim 22, wherein interposing a first lens combination comprises positioning at least a first movable lens in the optical path of light traveling from a scene to the detector.

28. The method as in claim 27, wherein interposing a second lens combination comprises removing the at least a first movable lens from the optical path of light traveling from a scene to the detector, and positioning at least a second movable lens into the optical path of light traveling from a scene to the detector.

29. The method as in claim 22, wherein interposing a second lens combination comprises maintaining a stationary lens in the optical path of light traveling from a scene to the detector.

30. The method as in claim 29, wherein interposing a first lens combination comprises positioning at least one movable lens, in addition to the stationary lens, in the optical path of light traveling from a scene to the detector.

31. The method as in claim 29, wherein interposing a second lens combination further comprises positioning at least a first movable lens, in addition to the stationary lens, in the optical path of light traveling from a scene to the detector.

32. The method as in claim 31, wherein interposing a first lens combination comprises removing the at least a first movable lens from the optical path of light traveling from a scene to the detector, and positioning at least a second movable lens into the optical path of light traveling from a scene to the detector.

33. The method as in claim 22, wherein interposing a second lens combination comprises positioning at least a first movable lens in the optical path of light traveling from a scene to the detector.

34. The method as in claim 33, wherein interposing a first lens combination comprises removing the at least a first movable lens from the optical path of light traveling from a scene to the detector, and positioning at least a second movable lens into the optical path of light traveling from a scene to the detector.

35. The method as in claim 22, wherein the method is implemented in a scanner.