Omni-directional radiation source and object locator

• US 20040104334A1
• Filed: 09/16/2003
• Published: 06/03/2004
• Est. Priority Date: 03/20/2001
• Status: Abandoned Application

• Current Assignee: Wave Group Ltd.
• Original Assignee: Wave Group Ltd.
• Inventors: Eyal, Reuven, Gal, Ehud, Liteyga, Gennadiy, Graisman, Gil
• Application Number:
  US10/471,958
• Publication Number:
  US 20040104334A1
• Time in Patent Office: Days
• US Class Current: 250/203.6
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Abstract

The current invention describes a method for determining azimuth and elevation angles of a radiation source or other physical objects located anywhere within an cylindrical field of view. The invention makes use of an omni-directional imaging system comprising of reflective surfaces, an image sensor and an optional optical filter for filtration of the desired wavelengths. The said imaging system is designed to view an omni-directional field of view using a single image sensor and with no need for mechanical scan for coverage of the full field of view. Use of two such systems separated by a known distance, each providing a different reading of azimuth and elevation angle of the same object, enables classic triangulation for determination of the actual location of the object. The invention is designed to enable use of low cost omni-directional imaging systems for location of radiation sources or objects. Many additional needs and applications are envisaged for such a method. Those needs include: location of flares and torches in search and rescue operations at sea or over land, detection of aircraft in close proximity for flight safety in VFR flight conditions, detection and location of weapon systems that employ Laser Range Finders, detection and warning of Laser Target Designators used in conjunction with surface launched or air dropped precision guided munitions, operation of Infra-red countermeasures, location of sparks resulted by enemy fire etc.

Claims

1. A method for determining elevation angle of an object imaged by a focal plane array sensor, comprising the following stages:

a. Imaging a cylindrical field of view using an omni-directional imaging system which comprises of an omni-directional lens assembly and a focal plane array.

b. Detection of an object imaged by a first sensor element on the said focal plane array.

c. Registration of the coordinates of said first sensor element relative to its position on the said focal plane array.

d. Registration of the coordinates of a second sensor element which occupies the center of the entire image, relative to its position on the said focal plane array.

e. Determination of the distance between said first sensor element and said second sensor element.

f. Determination of a transformation function, which assigns each said distance the appropriate elevation angle value, said transformation function is compatible to the design of the omni-directional imaging system.

g. Extraction of elevation angle value which corresponds to the said distance value from the said transformation function.

Wherein said focal plane array images an omni-directional field of view.

2. A method of claim 1, wherein said omni-directional lens assembly comprises reflective lenses.

3. A method of claim 1, wherein said detection of an object is accomplished by software processing of the image.

4. A method of claim 1, wherein said detection of an object is performed by an electronic circuit connected to said focal plane array.

5. An electronic circuit of claim 4, designed to detect charge changes on the said focal plane array and register the coordinates of sensor elements in which changes have been detected.

6. A method of claim 1, further comprising placement of an optical filter, anywhere along the optical path of light rays captured by the said omni-directional imaging system, selected to insure filtration of specific wavelengths, and covering the entire field of view.

7. An optical filter of claim 6, comprising of a multitude of optical filters.

8. A method of claim 1, wherein said object is a radiation source.

9. A radiation source of claim 8, which emits in the visible spectrum.

10. A radiation source of claim 8, which emits in the invisible spectrum.

11. A method for determining azimuth angle of an object imaged by a focal plane array sensor, comprising the following stages:

a. Imaging a cylindrical field of view using an omni-directional imaging system which comprises of an omni-directional lens assembly and a focal plane array.

b. Detection of an object imaged by a first sensor element on the said focal plane array.

c. Registration of the coordinates of said first sensor element relative to its position on the said focal plane array.

d. Registration of the coordinates of a second sensor element which occupies the center of the entire image, relative to its position on the said focal plane array.

e. Determination of the distance between said first sensor element and said second sensor element.

f. Superposition of a virtual two dimensional coordinate system upon said focal plane array, in a way that the origin of said coordinate system coincides with the said second sensor element.

g. Alignment of one of the axes of said coordinate system with true north.

h. Determination of the angle between the line connecting said first sensor element with said second sensor element and the axis aligned with true north—

said angle being the azimuth angle

Wherein said focal plane array images an omni-directional field of view.

12. A method of claim 11, wherein said omni-directional lens assembly comprises reflective lenses.

13. A method of claim 11, wherein said detection of an object is accomplished by software processing of the image.

14. A method of claim 11, wherein said detection of an object is performed by an electronic circuit connected to said focal plane array.

15. An electronic circuit of claim 14, designed to detect charge changes on the said focal plane array and register the coordinates of sensor elements in which changes have been detected.

16. A method of claim 11, further comprising placement of an optical filter, anywhere along the optical path of light rays captured by the said omni-directional imaging system, selected to insure filtration of specific wavelengths, and covering the entire field of view.

17. An optical filter of claim 16, comprising of a multitude of optical filters.

18. A method of claim 11, wherein said object is a radiation source.

19. A radiation source of claim 18, which emits in the visible spectrum.

20. A radiation source of claim 18, which emits in the invisible spectrum.