Method and device for imaging test objects by means of electromagnetic waves, in particular for inspecting individuals for suspicious items

• US 7,609,196 B2
• Filed: 03/07/2008
• Issued: 10/27/2009
• Est. Priority Date: 09/07/2005
• Status: Active Grant

• Current Assignee: Friedrich-Alexander-Universitat Erlangen-Nurnberg, Smiths Heimann GmbH (Smiths Group International Holdings Ltd.)
• Original Assignee: Smiths Heimann GmbH (Smiths Group International Holdings Ltd.)
• Inventors: Weinzierl, Jochen, Gumbmann, Frank, Tran, Hue-Phat, Schmidt, Lorenz-Peter, Jeck, Michael
• Primary Examiner(s): Lobo; Ian J
• Application Number:
  US12/044,218
• Publication Number:
  US 20080211713A1
• Time in Patent Office: 599 Days
• Field of Search: 342/22, 342/25.A
• US Class Current: 342/25.00A
• CPC Class Codes: G01S 13/02 Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 13/9082 Rotating SAR [ROSAR]
• CPC Class Codes: G01S 13/9088 Circular SAR [CSAR, C-SAR]
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation

Abstract

A method for imaging test objects by means of electromagnetic waves, in particular for the purpose of checking individuals for suspicious articles, in which method the test object is illuminated by electromagnetic waves, the scattered waves are received and evaluated for an imaginal representation of the test object on the basis of the synthetic aperture principle (SAR). A synthetic aperture is produced by the waves output by an antenna being concentrated initially in spatial terms, the point of high concentration being moved on a reflector along a circle.

Claims

1. A method for imaging test objects or inspecting individuals for suspicious items by electromagnetic waves, comprising the steps of

providing a synthetic aperture by first spatially concentrating electromagnetic waves emitted by an antenna to provide multiple locations of high concentration of said electromagnetic waves,

manipulating at least one location of high concentration to provide a moving virtual antenna;

illuminating a test object or individual with said moving virtual antenna of said electromagnetic waves; and

receiving and analyzing scattered electromagnetic waves resulting from said illuminating step using synthetic aperture imaging (SAR) to display an image of the test object.

2. The method according to claim 1, wherein said electromagnetic waves comprise millimeter waves having a frequency between 1 GHz and 10 THz.

3. The method according to claim 1, wherein parallel diverging cones of rays are sequentially produced by a quasi-optical element through rotation of the antenna.

4. The method according to claim 1, wherein parallel diverging cones of rays with a changing angle of inclination are sequentially produced by a quasi-optical element through rotation of the antenna so that the cones of rays remain aimed at a substantially same point in space.

5. The method according to claim 1, wherein said electromagnetic waves comprise millimeter waves having a frequency between 30 GHz and 300 GHz.

6. The method according to claim 1, comprising projecting said electromagnetic waves emitted from said antenna onto a rotating component from which the waves are reflected and concentrated onto a reflector, wherein the reflector emits a moving, diverging cone of rays.

7. The method according to claim 1, wherein said antenna which emits said electromagnetic waves is a rotatable antenna, and said electromagnetic waves are projected onto a focusing element, from which focusing element said electromagnetic waves are concentrated onto a quasi-optical element, and wherein the quasi-optical element emits a diverging cone of rays that are displaced in parallel during rotational motion of the virtual antenna.

8. The method according to claim 1, wherein a virtual source is produced by a Nipkow disk, which covers a strip upon which the waves emitted by an antenna are focused.

9. The method according to claim 1, wherein at least one transmitting antenna and at least one spatially separated receiving antenna are used to provide a moving virtual antenna.