Holographic arrays for threat detection and human feature removal

• US 7,034,746 B1
• Filed: 03/24/2005
• Issued: 04/25/2006
• Est. Priority Date: 03/24/2005
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: McMakin, Douglas L., Lechelt, Wayne M, Sheen, David M., Severtsen, Ronald H., Hall, Thomas E.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US11/088,555
• Time in Patent Office: 397 Days
• Field of Search: 342/21, 342/22, 342 25 R- 25 F, 342/175, 342/176, 342/179, 342/188, 342190-197, 342/351, 342361-366
• US Class Current: 342/179
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195

Abstract

A method and apparatus to remove human features utilizing at least one transmitter transmitting a signal between 200 MHz and 1 THz, the signal having at least one characteristic of elliptical polarization, and at least one receiver receiving the reflection of the signal from the transmitter. A plurality of such receivers and transmitters are arranged together in an array which is in turn mounted to a scanner, allowing the array to be passed adjacent to the surface of the item being imaged while the transmitter is transmitting electromagnetic radiation. The array is passed adjacent to the surface of the item, such as a human being, that is being imaged. The portions of the received signals wherein the polarity of the characteristic has been reversed and those portions of the received signal wherein the polarity of the characteristic has not been reversed are identified. An image of the item from those portions of the received signal wherein the polarity of the characteristic was not reversed is then created.

Claims

1. A method to remove human features in an imaging system having at least one transmitter transmitting electromagnetic radiation between 200 MHz and 1 THz and at least one receiver receiving the reflective signal from said transmitter comprising the steps of:

a. transmitting a signal having at least one characteristic of elliptical polarization towards an item,

b. receiving a reflection of said signal,

c. identifying those portions of said received signal wherein the polarity of said characteristic is reversed and those portions of said received signal wherein the polarity of said characteristic is not reversed,

d. creating an image from those portions of said received signal wherein the polarity of said characteristic is not reversed.

2. The method of claim 1 wherein said elliptical polarization is circular polarization.

3. The method of claim 1 wherein said characteristic is selected from the group of right handedness and left handedness.

4. The method of claim 1 wherein said signal is fully-polarimetric.

5. The method of claim 1 wherein a plurality of receivers and transmitters are arranged in an array and are passed adjacent to the surface of the item being imaged.

6. The method of claim 5 wherein said the step of passing the array adjacent to the surface of the item being imaged is selected from the group of circling the array around the surface of said item, and moving the array in a rectilinear plane parallel to the surface of said item.

7. An imaging system comprising:

a. at least one transmitter configured to transmit electromagnetic radiation at an item between 200 MHz and 1 THz and having at least one characteristic of elliptical polarization,

b. at least one receiver capable of receiving at least one characteristic of elliptical polarization from a reflected signal from said transmitter,

c. a computer configured to identify those portions of said received signal wherein the polarity of said characteristic is reversed and those portions of said received signal wherein the polarity of said characteristic is not reversed, and create an image from those portions of said received signal wherein the polarity of said characteristic is not reversed.

8. The imaging system of claim 7 wherein said elliptical polarization is circular polarization.

9. The imaging system of claim 7 wherein said characteristic is selected from the group of right handedness and left handedness.

10. The imaging system of claim 7 wherein said signal is fully-polarimetric.

11. The imaging system of claim 7 wherein a plurality of receivers and transmitters are arranged in an array and are mounted on a scanner capable of passing the array adjacent to the surface of the item being imaged.

12. The imaging system of claim 11 wherein the scanner is capable of rotating the array around the surface of said item.

13. The imaging system of claim 11 wherein the scanner is capable of passing the array in a rectilinear plane parallel to the surface of said item.