Electromagnetic scanning imager

• US 7,626,400 B2
• Filed: 02/14/2006
• Issued: 12/01/2009
• Est. Priority Date: 02/15/2005
• Status: Active Grant

• Current Assignee: Walleye Technologies, Inc.
• Original Assignee: Walleye Technologies, Inc.
• Inventors: Holbrook, David S., Adams, Christopher P.
• Primary Examiner(s): Dole; Timothy J
• Application Number:
  US11/353,882
• Publication Number:
  US 20070046525A1
• Time in Patent Office: 1,386 Days
• Field of Search: 324637-646, 342/22
• US Class Current: 324/642
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/426 Scanning radar, e.g. 3D radar G01S13/66 takes precedence
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: H01Q 19/065 Zone plate type antennas

Abstract

In one aspect, the present invention provides an imager, preferably portable, that includes a source of electromagnetic radiation capable of generating radiation with one or more frequencies in a range of about 1 GHz to about 2000 GHz. An optical system that is optically coupled to the source focuses radiation received therefrom onto an object plane, and directs at least a portion of the focused radiation propagating back from the object plane onto an image plane. The imager further includes a scan mechanism coupled to the optical system for controlling thereof so as to move the focused radiation over the object plane. A detector optically coupled to the lens at the image plane detects at least a portion of the radiation propagating back from a plurality of scanned locations in the object plane, thereby generating a detection signal. A processor that is in communication with the detector generates an image of at least a portion of the object plane based on the detection signal.

Claims

1. An imaging system, comprising:

a housing adapted for movement over an object plane,

at least one sensor coupled to the housing for generating data indicative of locations and orientations of the housing over said object plane, wherein said housing comprises;

a source of electromagnetic radiation for generating radiation with one or more frequencies in a range of about 1 GHz to about 2000 GHz,

an optical system optically coupled to said source so as to focus radiation received therefrom onto the object plane, said optical system directing at least a portion of the focused radiation propagating back from the object plane onto an image plane,

a scan mechanism coupled to said optical system for controlling thereof so as to move the focused radiation over the object plane,

a detector optically coupled to said optical system at the image plane to detect at least a portion of the radiation propagating back from a plurality of scanned locations in the object plane, thereby generating a time-dependent detection signal, and

a processor in communication with the detector to generate an image of at least a portion of the object plane based on said detection signal.

2. The imaging system of claim 1, wherein said processor maps variation of said varying detection signal to one or more respective locations in the object plane from which the back-propagating radiation giving rise to that detection signal originates.

3. The imaging system of claim 1, further comprising a position sensor coupled to the scan mechanism for determining a position thereof relative to a reference position.

4. The imaging system of claim 3, wherein said position sensor is in communication with said processor to communicate the position of the scan mechanism to the processor.

5. The imaging system of claim 1, further comprising a display in communication with said processor for displaying said image.

6. The imaging system of claim 1, wherein said scan mechanism causes the optical system to generate a generally elliptical scan pattern of the radiation over the object plane.

7. The imaging system of claim 6, wherein said scan mechanism causes the optical system to generate a circular scan pattern of the radiation over the object plane.

8. The imaging system of claim 1, wherein said housing is adapted to be moved by a user so as to scan the radiation, in combination with said scan mechanism, in two dimensions in the object plane.

9. The imaging system of claim 8, wherein said processor maps a variation of said detection signal to said scanned locations so as to generate an image of a region in said object plane including said scanned locations.

10. The imaging system of claim 8, wherein for each image point coordinate corresponding to one of said scanned locations, the display presents a brightness proportional to a strength of the detection signal corresponding to back-propagating radiation from that scanned location.

11. The imaging system of claim 8, further comprising means for communicating said data indicative of locations and orientations of the housing to the processor, said processor utilizing said data to map the detection signal to the scanned locations.

12. The imaging system of claim 1, wherein said radiation source and said detector are formed as a single transmit/receive module operating in said frequency range of about 1 GHz to about 2000 GHz.

13. The imaging system of claim 1, wherein the housing is a portable housing containing said radiation source, said optical system, said scan mechanism and said detector.

14. The imaging system of claim 13, further comprising an electronic processing and display module (EPDM) that includes said processor.

15. The imaging system of claim 14, wherein said EPDM is integrated within said portable housing.

16. The imaging system of claim 14, further comprising a second housing, separate from said portable housing, for containing said EPDM, said second housing being in data or signal communication with said portable housing.

17. The imaging system of claim 14, wherein said EPDM comprises a display module for displaying said image.

18. The imaging system of claim 1, wherein the processor operates on said time-dependent signal to generate a plurality of overlapping image frames and correlates said image frames to form said image.

19. The imaging system of claim 18, wherein said processor utilizes one or more pixels in an overlap region of two image frames as reference to determine relative positions of the other pixels in the two image frames.

20. The imaging system of claim 1, wherein said optical system is rotatable about a rotation axis that is substantially parallel with and displaced from an optical axis thereof so as to move said focused radiation, in combination with the movement of the housing, over a plurality of locations corresponding to said plurality of scanned locations in a two dimensional region of the object plane.

21. The imaging system of claim 1, wherein said optical system includes at least one optical element rotatable about a rotation axis that is substantially parallel with and displaced from an optical axis thereof so as to move said focused radiation, in combination with the movement of the housing, over a plurality of locations corresponding to said plurality of scanned locations in a two dimensional region of the object plane.

22. The imaging system of claim 21, wherein said at least one optical element is a focusing element.

23. The imaging system of claim 21, wherein said at least one optical element is a radiation transmissive element.

24. The imaging system of claim 21, wherein said at least one optical element is a diffractive optical element.

25. A portable imager, comprising:

a portable housing adapted for movement over an object plane, comprising;

a source for generating electromagnetic radiation with one or more frequency components in a range of about 1 GHz to about 2000 GHz,

means for directing radiation from the source to an object plane and directing at least a portion of the radiation propagating back from the object plane to an image plane,

means coupled to the radiation-directing means for controlling thereof so as to scan the radiation over at least a portion of the object plane,

means for generating signals indicative of locations and orientations of said housing over said object plane,

means for detecting radiation propagating back from a plurality of scanned locations in the object plane and generating a detection signal, and

means for analyzing said detection signal and said signals indicative of the locations and orientations of the housing so as to generate an image of at least a portion of the object plane.

26. An imaging system, comprising:

a handheld housing, comprising

a source of electromagnetic radiation for generating radiation having one or more frequencies in a range of about 1 GHz to about 2000 GHz,

an optical system for directing radiation generated by the source onto an object plane and directing at least a portion of the radiation propagating back from the object plane onto an image plane,

a scan mechanism coupled to said focusing system for controlling thereof so as to provide a one-dimensional scan of the radiation over the object plane,

a detector optically coupled to said optical system at the image plane to detect at least a portion of said back-propagating radiation to generate a time-dependent detection signal,

at least one sensor coupled to the handheld housing for generating data indicative of locations and orientations of the handheld housing, and

a processor coupled to the detector to receive said detection signal,

wherein said housing is adapted for movement so as to scan the radiation, in combination with said one-dimensional scan, over a plurality of locations in a two-dimensional region of the object plane.

27. The imaging system of claim 26, wherein the processor generates an image of said region based on the detection signal corresponding to the scanned locations.

28. The imaging system of claim 27, wherein the processor maps the detection signal temporally to one or more of said scanned locations for generating said image.

29. The imaging system of claim 27, further comprising a display in communication with said processor for displaying said image.

30. The imaging system of claim 26, wherein said one-dimensional scan is characterized by a generally elliptical path over the object plane.

31. An imaging system, comprising:

a housing adapted for movement over a surface located at a distance from an object plane,

a transmit/receive module disposed in said housing for generating and detecting electromagnetic radiation,

an optical system optically coupled to the transmit/receive module to focus radiation received therefrom onto the object plane,

said optical system directing at least a portion of radiation propagating back from the object plane onto the transmit/receive module,

a scanning mechanism coupled to the optical system for rotating a focusing element of the optical system about a rotation axis thereby moving said focused radiation over a region of the object plane,

a position sensor in communication with said scanning mechanism to generate signals indicative of position of the focusing element relative to a reference position,

a location-determining subsystem disposed in said housing for generating signals indicative of locations and orientations of said housing on the surface as the housing is moved over that surface, and

a processor in communication with said transmit/receive module, said position sensor and said subsystem,

wherein said processor generates an image of at least a portion of said object plane based on said detected back-propagating radiation and signals generated by said position sensor and said subsystem.

32. The imaging system of claim 31, wherein said optical system and scanning mechanism are disposed in the housing.

33. The imaging system of claim 31, wherein said location-determining subsystem comprises one or more inertial sensors.

34. The imaging system of claim 31, further comprising a display in communication with said processor for displaying said image.

35. The imaging system of claim 34, wherein said processor applies a plurality of image drive signals to said display so as to effect display of said image.

36. The imaging system of claim 31, wherein said processor generates a set of image point coordinates in a coordinate space of the object plane based on signals received from said position sensor and said location-determining subsystem.

37. The imaging system of claim 31, wherein said focusing element comprises a diffractive optical element.

38. The imaging system of claim 37, wherein said diffractive optical element comprises diffractive zones disposed about an optical axis that is offset from said rotation axis.

39. The imaging system of claim 31, wherein said location-determining subsystem comprises one or more optical sensors.

40. The imaging system of claim 31, wherein said location-determining subsystem comprises a tracking ball having orthogonal rotation encoding devices.

41. A method of imaging, comprising:

providing a handheld housing adapted for movement over an object plane and having a source of electromagnetic radiation for generating radiation with one or more frequency components in a range of about 1 GHz to about 2000 GHz, said housing further including at least one sensor for generating signals indicative of locations and orientations of the housing as it is moved over the object plane,

providing a focusing element in said housing that is optically coupled to said source, utilizing the focusing element to focus radiation from the source onto the object plane,

scanning the focused radiation over at least a portion of the object plane moving the housing over the object plane so as to illuminate, in combination with said scanning of the focused radiation, a plurality of locations over a two-dimensional region of the object plane,

detecting at least a portion of the radiation propagating back from said illuminated locations on the object plane thereby generating a time-dependent detection signal, and

analyzing said detection signal and said signals generated by said at least one sensor to form an image of the scanned portion of the object plane.

42. The method of claim 41, wherein the step of focusing radiation further comprises directing the radiation to the object plane along a direction forming a non-zero angle relative to a normal to the object plane.

43. The method of claim 42, wherein said angle is about 7 degrees.