Active infrared signature detection device

• US 20020100875A1
• Filed: 01/31/2001
• Published: 08/01/2002
• Est. Priority Date: 01/31/2001
• Status: Active Grant

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Greene, Michael L.
• Granted Patent: US 6,448,558 B1
• Time in Patent Office: Days
• US Class Current: 250/353
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/025 Interfacing a pyrometer to an external device or network; User interface
• CPC Class Codes: G01J 5/026 Control of working procedures of a pyrometer, other than calibration; Bandwidth calculation; Gain control
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0806 Focusing or collimating elements, e.g. lenses or concave mirrors
• CPC Class Codes: G01J 5/0815 Light concentrators, collectors or condensers
• CPC Class Codes: G01J 5/0818 Waveguides

Abstract

The present invention is a device for detecting modulated or active infrared light comprises a photodiode mounted on the base aperture of a wave guide for focusing infrared light onto the photodiode. The wave guide is preferably pyramid shaped and has a reflective surface on the inner surface. The apex of the wave guide comprises an acute angle from about 5 degrees to about 10 degrees. Units to process the signal and amplify the signal are attached thereto. The device may also include a Fresnel lens and a means to adjust the voltage of the active infrared signal processing means to improve detection capabilities.

Claims

1. An active infrared light detection device, comprising:

a photodiode;

a wave guide having an inner surface comprising a reflective surface for focusing active infrared light onto the photodiode resulting in an active infrared signal;

an apex within the wave guide comprising an acute angle from about 5 degrees to about 10 degrees; and

,

means for processing the active infrared signal connected to the photodiode wherein the active infrared signal can be displayed visually or audibly.

2. The active infrared light detection device of claim 1, wherein the reflective surface comprises a first surface mirror.

3. The active infrared light detection device of claim 2, wherein the wave guide comprises a pyramid shape having a base aperture and a receipt aperture.

4. The active infrared light detection device of claim 3, wherein the base aperture comprises an area of from about 0.1 square inches to about 0.2 square inches.

5. The active infrared light detection device of claim 4, wherein the receipt aperture comprises an area from about 2 square inches to about 4 square inches.

6. The active infrared light detection device of claim 5, wherein the photodiode comprises a location substantially adjacent to the base aperture.

7. The active infrared light detection device of claim 6, wherein the photodiode can detect infrared light in a wave range from about 780 nanometers to about 1300 nanometers.

8. The active infrared light detection device of claim 7, wherein the apex comprises an angle of about 8 degrees.

9. The active infrared light detection device of claim 8, wherein the active infrared signal processing means comprises a voltage sensitive amplifier to discriminate frequencies of the active infrared signal.

10. The active infrared light detection device of claim 2, further comprising a lens located between the receipt aperture and an incoming infrared wave.

11. The active infrared light detection device of claim 10, wherein the lens comprises a location approximately adjacent to the receipt aperture.

12. The active infrared light detection device of claim 11, wherein the lens comprises a Fresnel lens.

13. The active infrared light detection device of claim 12, wherein the lens comprises a focal length greater than a distance between the base aperture and the receipt aperture.

14. The active infrared light detection device of claim 13, further comprising means for visual and audio output connected to the active infrared signal processing means.

15. The active infrared light detection device of claim 14, wherein the visual and audio output means comprise an LED and a speaker.

16. The active infrared light detection device of claim 1, further comprising means for adjusting the voltage of the infrared signal processing means.

17. The active infrared light detection device of claim 7, further comprising a Fresnel lens located approximately adjacent to the receipt aperture.

18. The active infrared light detection device of claim 17, further comprising means for adjusting the voltage of the active infrared signal processing means.

20. The method of claim 19, wherein the device further comprises a Fresnel lens located approximately adjacent to the receipt aperture.

19. A method of detecting active infrared light, comprising the steps of:

obtaining a device comprising a photodiode, a wave guide for focusing active infrared light onto the photo diode having an inner surface comprising a first surface mirror, an apex within the wave guide comprising an acute angle from about 5 degrees to about 10 degrees, means for processing an infrared signal connected to the photodiode wherein the active infrared signal can be displayed visually or audibly; and

,

initiating the device; and

,

pointing the wave guide towards an area to detect any active infrared light.