Infrared camera system and method

• US 7,477,309 B2
• Filed: 07/10/2003
• Issued: 01/13/2009
• Est. Priority Date: 07/10/2002
• Status: Active Grant

• Current Assignee: Frank J. Cuccias
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Cuccias, Frank J.
• Primary Examiner(s): Ye; Lin
• Assistant Examiner(s): SELBY, GEVELL V
• Application Number:
  US10/616,860
• Publication Number:
  US 20080309801A1
• Time in Patent Office: 2,014 Days
• Field of Search: 348/306, 348/342, 348/335, 348/222.1, 356/418, 356/419
• US Class Current: 348/342
• CPC Class Codes: H04N 23/125 Colour sequential image capture, e.g. using a colour wheel
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• CPC Class Codes: H04N 23/661 Transmitting camera control signals through networks, e.g. control via the Internet
• CPC Class Codes: H04N 23/671 in combination with active ranging signals, e.g. using light or sound signals emitted toward objects
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

Infrared (IR) camera systems for and a method of obtaining infrared images of target subjects are provided. In one embodiment, an IR camera system (10) includes a lens (12), a number of IR pass filters (14), an optical detector (16), a processor (18) mounted on a circuit board (20), a distance sensor (22), a visible light sensor (24), an IR light sensor (26), an IR illuminator (28), and a number of video outputs (30), all of which may be disposed within an appropriately configured housing (32). The filters (14) are mounted on a juke-box like rack system (34) also included within the housing (32). The processor (18) determines which pass filter is needed in order to optimize the image and sends an electronic signal to the rack system (34) directing the rack system (34) to move the appropriate filter (14) into the optical pathway between the lens (12) and the optical detector (16) and pull all of the other IR filters (14) out of the optical pathway between the lens (12) and the optical detector (16).

Claims

1. An infrared camera system comprising:

an infrared illumination source operable to transmit infrared optical energy in the direction of a subject when an ambient infrared light level is determined to be insufficient;

a lens configured to collect optical energy conveyed from the subject;

a filter providing a plurality of pass bands associated with different center wavelengths within an infrared portion of the electromagnetic spectrum, said filter being operable to pass filter optical energy collected by said lens in accordance with any selected one of its plurality of pass bands;

an optical detector operable to generate an electrical signal representing an image of the subject in response to optical energy collected by said lens, pass filtered by said filter in accordance with a desired pass band selectable from among the plurality of pass bands, and subsequently incident on said optical detector;

a control device operable to select the desired pass band from among the plurality of pass bands provided by said filter, wherein said control device comprises a microprocessor and wherein said microprocessor selects the desired pass band based on at least one of an ambient visible light level and an ambient infrared light level;

a visible light sensor operable to measure the ambient visible light level; and

an infrared light sensor operable to measure the ambient infrared light level;

wherein said infrared illumination source is operated to transmit infrared optical energy in the direction of the subject when the ambient infrared light level measured by said infrared light sensor is determined by said microprocessor to be insufficient.

2. The system of claim 1 wherein at least two of the pass bands of said filter overlap.

3. The system of claim 1 wherein none of the pass bands of said filter overlap.

4. The system of claim 1 wherein said filter comprises:

a plurality of separate filters having fixed pass bands; and

a switching device operable to interpose each of said filters in an optical pathway between said lens and said optical detector.

5. The system of claim 4 wherein said plurality of separate filters comprises first, second, third and fourth filters having pass bands centered around center wavelengths of 700 nm, 800 nm, 900 nm, and 1000 nm, respectively.

6. The system of claim 5 wherein the pass band of each of said first, second, third and fourth filters is +/−

20 nm from the center wavelength thereof.

7. The system of claim 4 wherein each said separate filter comprises glass retained within a metal ring.

8. The system of claim 7 wherein said separate filters are coupled with said switching device by a hinge attached to said metal ring, said switching device being operable to pivot said filters about said hinge in order to selectively interpose said filters into said optical pathway.

9. The system of claim 1 wherein said filter comprises:

filter pane interposed in an optical pathway between said lens and said optical detector, said filter pane providing a pass band having a center wavelength that is adjustable over a range of wavelengths in response to a voltage level applied thereto.

10. The system of claim 9 wherein the range of wavelengths over which the center wavelength of the pass band of said filter pane is adjustable ranges from a center wavelength of 700 nm to a center wavelength of 1000 nm.

11. The system of claim 10 wherein the pass band of said filter pane comprises +/−

20 nm from the center wavelength thereof.

12. The system of claim 1 wherein said filter comprises:

a filter disk having a plurality of individual filter windows, each said filter window having a fixed pass band associated with a different center wavelength, said disk being configured for rotation about an axis thereof to interpose a selected one of said filter windows in an optical pathway between said lens and said optical detector.

13. The system of claim 12 wherein the center wavelengths of the pass bands of said filter windows vary from a shorter wavelength to a longer wavelength in predetermined increments.

14. The system of claim 13 wherein the shorter wavelength is 700 nm, the longer wavelength is 1000 nm, and the predetermined increments are 10 nm.

15. The system of claim 12 wherein the pass band of each said filter window comprises +/−

20 nm from the center wavelength thereof.

16. The system of claim 1 wherein said filter comprises:

a filter disk having a pass band associated with a center wavelength that varies in a continuous manner proceeding around a circumference of said disk, said disk being configured for rotation about an axis thereof to interpose a different section of said filter disk in an optical pathway between said lens and said optical detector.

17. The system of claim 16 wherein the center wavelength of the pass band of said filter disk varies from a shorter wavelength to a longer wavelength in a predetermined increment over a predetermined distance measured along the circumference of said filter disk.

18. The system of claim 17 wherein the shorter wavelength is 700 nm, the longer wavelength is 1000 nm, the predetermined increment is 1.2 nm and the predetermined distance is 1 degree of arc.

19. The system of claim 16 wherein the pass band of said filter disk comprises +/−

5 nm from the center wavelength thereof.

20. The system of claim 1 wherein said optical detector comprises a charge-couple-device.

21. The system of claim 1 wherein said lens comprises an auto-focus lens controllable by said microprocessor, and wherein said microprocessor adjusts said auto-focus lens in order to focus the image of the subject on said optical detector based on a distance between said auto-focus lens and the subject.

22. The system of claim 21 further comprising a distance sensor operable to measure the distance between said auto-focus lens and the subject.

23. The system of claim 1 wherein said microprocessor is operable to convert the electrical signal generated by said optical sensor into a video signal.

24. The system of claim 23 further comprising at least one video connector for outputting the video signal via a wired connection.

25. The system of claim 23 further comprising a wireless transmitter for outputting the video signal via a wireless connection.

26. The system of claim 25 wherein said wireless transmitter comprises an 802.11 wireless transmitter.

27. An infrared camera system comprising:

a lens configured to collect optical energy conveyed from a subject;

a filter providing a pass band associated with a center wavelength within an infrared portion of the electromagnetic spectrum, said filter being operable to pass filter optical energy collected by said lens in accordance with its pass band;

an optical channel between said lens and said filter;

an optical detector operable to generate an electrical signal representing an image of the subject in response to optical energy collected by said lens, directed though said optical channel to said filter, pass filtered by said filter in accordance with the pass band of said filter, and subsequently incident on said optical detector; and

a micro-transmitter operable to transmit the electrical signal via at least one of a wired communications link and a wireless communications link;

wherein said lens, filter, optical channel, optical detector and micro-transmitter are mounted on one of a pair of glasses and a vest wearable by a person.

28. The system of claim 27 wherein said optical channel comprises a shielded fiber optic cable.

29. The system of claim 27 wherein a focal length of said lens is fixed.

30. The system of claim 27 wherein the pass band of said filter is fixed.

31. The system of claim 27 wherein said optical detector comprises a charge-couple-device.

32. An infrared camera system comprising:

a lens configured to collect optical energy conveyed from a subject;

a filter providing a plurality of pass bands associated with different center wavelengths within an infrared portion of the electromagnetic spectrum, said filter being operable to pass filter optical energy collected by said lens in accordance with any selected one of its plurality of pass bands, said filter comprising a filter disk having a pass band associated with a center wavelength that varies in a continuous manner proceeding around a circumference of said disk, said disk being configured for rotation about an axis thereof to interpose a different section of said filter disk in an optical pathway between said lens and said optical detector, wherein the center wavelength of the pass band of said filter disk varies from a shorter wavelength to a longer wavelength in a predetermined increment over a predetermined distance measured along the circumference of said filter disk, and wherein the shorter wavelength is 700 nm, the longer wavelength is 1000 nm, the predetermined increment is 1.2 nm and the predetermined distance is 1 degree of arc;

an optical detector operable to generate an electrical signal representing an image of the subject in response to optical energy collected by said lens, pass filtered by said filter in accordance with a desired pass band selectable from among the plurality of pass bands, and subsequently incident on said optical detector; and

a control device operable to select the desired pass band from among the plurality of pass bands provided by said filter.