COMPRESSIVE PASSIVE MILLIMETER WAVE IMAGER

• US 20130257646A1
• Filed: 03/28/2012
• Published: 10/03/2013
• Est. Priority Date: 03/28/2012
• Status: Active Grant

• Current Assignee: UChicago Argonne LLC
• Original Assignee: UChicago Argonne LLC
• Inventors: Elmer, Thomas W., Koehl, Eugene R., Heifetz, Alexander, Raptis, Apostolos C., GOPALSAMI, Nachappa, Liao, Shaolin
• Granted Patent: US 8,941,061 B2
• Time in Patent Office: Days
• US Class Current: 342/179
• CPC Class Codes: G01K 11/006 using measurement of the effect of a material on microwaves or longer electromagnetic waves, e.g. measuring temperature via microwaves emitted by the object G01K17/003, G01J5/00 take precedence; measuring the effect of a material on X-, gamma- or particle radiation G01K11/30
• CPC Class Codes: G01S 13/89 for mapping or imaging

Abstract

A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is position to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

Claims

1. A method for millimeter-wave imaging comprising:

positioning a portion of an extended Hadamard mask within an opening of a template with an opening of size p×

q, the extended Hadamard mask having a size (2p−

1)×

(2q−

1) wherein p and q are prime numbers, the Hadamard mask receiving millimeter waves from a source;

transmitting a portion of the millimeter waves through transmit pixels in the Hadamard mask;

reflecting a portion of the millimeter waves by reflect pixels in the Hadamard mask;

focusing the transmitted portion of the millimeter waves; and

receiving the focused millimeter waves at a detector.

2. The method of claim 1, wherein pixel size is s>

λ

/2 where λ

s the wavelength of the received millimeter waves.

3. The method of claim 1, further comprising imaging an object through an imaging lens, wherein an image plane is projected.

4. The method of claim 3, wherein the extended Hadamard mask is positioned at the image plane.

5. The method of claim 4, wherein the portion of the Hadamard mask is at least 40 pixels by 40 pixels.

6. The method of claim 1, further comprising the application of a relaxation technique to reconstruct the image.

7. The method of claim 5, wherein image is reconstructed according to

8. The method of claim 1, wherein q=p+2.

9. A system for passive millimeter wave imaging a source comprising:

an extended Hadamard mask comprising a plurality of pixels, the pixels including transmitting pixels and non-transmitting pixels, the transmitting pixels allowing millimeter waves to pass through;

a template with an opening smaller than the extended Hadamard mask, the template positioned between the source and the extended Hadamard mask

a focusing lens positioned behind the extended Hadamard mask relative to the source and positioned to receive millimeter waves from the extended Hadamard mask;

a receiving antenna associated with the focusing lens to receive millimeter waves; and

a radiometer in communication with the receiving antenna.

10. The system of claim 9, further comprising an imaging lens positioned between the source and the extended Hadamard mask.

11. The system of claim 10, wherein the extended Hadamard mask is positioned at the imaging lens'"'"' image plane.

12. The system of claim 9, further comprising a 2-axis stage in communication with the extended Hadamard mask

13. The system of claim 9, wherein the extended Hadamard mask has a size a size (2p−

1)×

(2q−

1) and the template opening has a size p×

q.

14. The system of claim 13, wherein p and q are prime numbers.

15. The system of claim 9 wherein pixel size is s>

λ

/2 where λ

s the wavelength of the millimeter waves

16. A computer-implemented machine for imaging an object, comprising:

a processor; and

a tangible computer-readable medium operatively connected to the processor and including computer code configured to control;

imaging an object via an imaging lens at an image plane;

positioning a Hadamard mask at the image plane;

interacting millimeter waves from the object with the Hadamark mask;

transmitting a portion of the millimeter waves through transmit pixels in the Hadamark mask;

focusing the transmitted portion of the millimeter waves; and

receiving the focused millimeter waves.

17. The computer-implemented machine of claim 16, wherein the positioning of the Hadamard mask comprises selecting a Hadamard mask.

18. The computer-implemented machine of claim 16, wherein selecting the Hadamard mask comprises selecting an area of size p×

q from an extended Hadamard mask of size (2p−

1)×

(2q−

1).

19. The computer-implemented machine of claim 18, wherein selecting the Hadamard mask comprises selecting a subset of the pixels starting at every nth pixel of the extended Hadamard mask, where n is greater than 1.

20. The computer implemented machine of claim 16, further including computer code configured to control the application of a relaxation technique to reconstruct the image.