Imaging system

• US 6,429,418 B1
• Filed: 07/19/1999
• Issued: 08/06/2002
• Est. Priority Date: 12/02/1996
• Status: Expired due to Fees

• Current Assignee: Australian National University
• Original Assignee: Australian National University
• Inventors: Srinivasan, Mandyam Veerambudi, Chahl, Javaan Singh
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Nguyen, Tu T.
• Application Number:
  US09/308,646
• Time in Patent Office: 1,114 Days
• Field of Search: 250/208.1, 250/203.2, 250/203.3, 250/203.6, 250/216, 250/201.5, 250/201.7, 250/559.12, 250/201.2, 396/123, 396/124, 356/3.05, 356/3.16
• US Class Current: 250/216
• CPC Class Codes: G08B 13/19628 of wide angled cameras and camera groups, e.g. omni-directional cameras, fish eye, single units having multiple cameras achieving a wide angle view
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof

Abstract

A system for generating an image of a space includes a camera having an image plane and a field of view. A reflective surface is positioned within the field of view of the camera and configured to reflect radiation from the space onto the image plane of the camera. The camera occludes radiation from being received at the reflective surface from an area of the space and the reflective surface is configured such that the occluded area is of substantially constant or decreasing area with increasing distance into the space.

Claims

1. A system for generating an image of a space, said system including a camera having an image plane and a field of view, a reflective surface positioned within the field of view of said camera and configured to reflect radiation from said space onto the image plane of said camera, said camera occluding radiation from being received at said reflective surface from an area of said space, and said reflective surface being configured such that said occluded area is of substantially constant or decreasing area with increasing distance into said space from said reflective surface.

2. A system as claimed in claim 1 wherein said reflective surface is circularly symmetric and the image plane of the camera is arranged on the axis of symmetry.

3. A system as claimed in claim 2 wherein said reflective surface includes concentrically arranged concave and convex portions.

4. A system as claimed in claim 3 wherein said reflective surface includes a central generally concave portion surrounded by a generally convex portion in turn surrounded by an outer generally concave portion.

5. A system as claimed in claim 1 wherein said reflective surface includes a discontinuity to prevent imaging of the occluded region.

6. A system for generating an image of a space, said system including a camera having an image plane and a field of view, a reflective surface configured to reflect radiation from said space onto a secondary reflector positioned in the field of view of said camera and configured to reflect incident radiation from said reflective surface onto the image plane of said camera, said secondary reflector occluding radiation from an area of said space from reaching said reflective surface and said reflective surface being configured such that said occluded area is of substantially constant or decreasing area with increasing distance into said space from said reflective surface.

7. A system as claimed in claim 6 wherein said reflective surface is circularly symmetric and the image plane of the camera is arranged on the axis of symmetry.

8. A system as claimed in claim 7 wherein said reflective surface includes concentrically arranged concave and convex portions.

9. A system as claimed in claim 8 wherein said reflective surface includes a central generally concave portion surrounded by a generally convex portion in turn surrounded by an outer generally concave portion.

10. A system as claimed in claim 6 wherein said reflective surface includes a discontinuity to prevent imaging of the occluded region.

11. A system as claimed in claim 6 wherein an aperture is provided centrally in the reflector surface and said radiation is reflected from said secondary reflector to said camera through the aperture.

12. A system as claimed in claim 6 wherein said secondary reflector is a generally domed surface.

13. A system as claimed in claim 12 wherein said domed surface is smoothly curved.

14. A system as claimed in claim 6 wherein said secondary reflector is the surface of a cone.

15. A system as claimed in claim 14 wherein said reflective surface is described in polar co-ordinates (r, θ

) by the equation ${\left[\frac{r_0}{r}\right]}^K=\frac{\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{\alpha <br><br>}\right)}{\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(K<br><br>\left[\mathrm{\theta <br><br>}+\mathrm{\alpha <br><br>}-{90}^0\right]+\mathrm{\alpha <br><br>}\right)}$

where K is the gain

α

is the angle between the axis of symmetry and the secondary reflector surface $r_0=d+\frac{b}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\alpha <br><br>}\right)}$

d is the distance from the apex of said cone to said image plane and b is the diameter of the base of the cone.

16. A system for projecting an image into a space said system including a device to direct light representative of said image onto a reflective surface, said reflective surface being configured to reflect said light into said space in a pattern which generates said image in said space, said device to direct light occluding light from being reflected from said reflective surface into an area of said space and said reflective surface being configured such that said occluded area is of substantially constant or decreasing area with increasing distance into said space from said reflective surface.

17. A system as claimed in claim 16 wherein said reflective surface is circularly symmetric and the device to direct light is arranged on the axis of symmetry.

18. A system as claimed in claim 17 wherein said reflective surface includes concentrically arranged concave and convex portions.

19. A system as claimed in claim 18 wherein said reflective surface includes a central generally concave portion surrounded by a generally convex portion in turn surrounded by an outer generally concave portion.

20. A system as claimed in claim 16 wherein said reflective surface includes a discontinuity to prevent imaging of the occluded region.

21. A system for projecting an image into a space said system including a device to direct light representative of said image onto a secondary reflector configured to reflect incident light onto a reflective surface, said reflective surface being configured to reflect said light into said space in a pattern which generates said image in said space, said secondary reflector occluding light from being reflected from said reflective surface into an area of said space and said reflective surface being configured such that said occluded area is of substantially constant or decreasing area with increasing distance into said space from said reflective surface.

22. A system as claimed in claim 21 wherein said reflective surface is circularly symmetric and the device to direct light is arranged on the axis of symmetry.

23. A system as claimed in claim 22 wherein said reflective surface includes concentrically arranged concave and convex portions.

24. A system as claimed in claim 23 wherein said reflective surface includes a central generally concave portion surrounded by a generally convex portion in turn surrounded by an outer generally concave portion.

25. A system as claimed in claim 21 wherein said reflective surface includes a discontinuity to prevent imaging of the occluded region.

26. A system as claimed in claims 21 wherein an aperture is provided centrally in the reflector surface and said light is directed from said device to said secondary reflector through the aperture.

27. A system as claimed in claim 21 wherein said secondary reflector is a generally domed surface.

28. A system as claimed in claim 27 wherein said domed surface is smoothly curved.

29. A system as claimed in claim 21 wherein said secondary reflector is the surface of a cone.

30. A system as claimed in claim 29 wherein said reflective surface is described in polar co-ordinates (r, θ

) by the equation ${\left[\frac{r_0}{r}\right]}^K=\frac{\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{\alpha <br><br>}\right)}{\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(K<br><br>\left[\mathrm{\theta <br><br>}+\mathrm{\alpha <br><br>}-{90}^0\right]+\mathrm{\alpha <br><br>}\right)}$

where K is the gain

α

is the angle between the axis of symmetry and the secondary reflector surface $r_0=d+\frac{b}{2<br><br>\text{\hspace{1em}<br><br>}<br><br>\sin <br><br>\text{\hspace{1em}<br><br>}<br><br>\left(2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\alpha <br><br>}\right)}$

d is the distance from the apex of said cone to said image plane and b is the diameter of the base of the cone.