Three-dimensional holographical imaging

• US 9,046,605 B2
• Filed: 11/05/2012
• Issued: 06/02/2015
• Est. Priority Date: 11/05/2012
• Status: Active Grant

• Current Assignee: Curators of the University of Missouri (University of Missouri)
• Original Assignee: Curators of the University of Missouri (University of Missouri)
• Inventors: Ghasr, Mohammad Tayeb, Zoughi, Reza
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US13/668,445
• Publication Number:
  US 20140125516A1
• Time in Patent Office: 939 Days
• Field of Search: 342/22, 342 25 R- 25 F, 342/173, 342/179
• US Class Current: 1/1
• CPC Class Codes: G01S 13/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques

Abstract

A holographic imaging system including a transmission line coupled to an antenna at one end and to a signal source at another end. The antenna defines an aperture through which a signal generated by the signal source is transmitted incident to an object located remotely from the aperture and through which a signal reflected from the object is received by the antenna aperture. A standing wave probe phase-referenced to the antenna aperture samples the reflected signal. A detector connected to the standing wave probe receives the sampled reflected signal and provides an output signal that represents a real-valued signal proportional to an in-phase component of the reflected signal from the object. A processor executes an imaging algorithm for generating a multi-dimensional profile representative of the object based on the output signal from the detector.

Claims

1. A holographic imaging system comprising:

an antenna having a transmission line coupled thereto, said transmission line coupled to the antenna at one end and coupled to a signal source at another end, said antenna defining an aperture through which a signal generated by the signal source is transmitted incident to an object located remotely from the aperture and through which a signal reflected from the object is received by the antenna aperture;

a standing wave probe located at a distance from the antenna aperture, wherein the distance of the standing wave probe from the antenna aperture is a fraction of a wavelength of the signal generated by the signal source such that the standing wave probe is phase-referenced to the antenna aperture for sampling the reflected signal;

a detector connected to the standing wave probe and configured to receive the sampled reflected signal, the detector providing an output signal that represents a real-valued signal proportional to an in-phase component of the reflected signal from the object and determining a reflection coefficient from the remote object measured at the aperture of the antenna; and

a processor configured to execute an imaging algorithm for generating a multi-dimensional profile representative of the object based on the output signal from the detector.

2. The imaging system of claim 1, wherein the detector comprises a diode and wherein the output voltage of the diode is proportional to a real component of the reflected signal.

3. The imaging system of claim 1, further comprising a receiver operatively connected to the detector for receiving a signal proportional to the magnitude of the standing wave.

4. The imaging system of claim 1, wherein the standing wave probe is located adjacent to the aperture.

5. The imaging system of claim 1, wherein the distance of the standing wave probe from the aperture is defined as d≦

λ

_g/4, where λ

_g is a guide wavelength at a mid-band frequency of the source signal.

6. The imaging system of claim 1, wherein the output signal is phase-referenced to the antenna aperture at substantially all frequencies.

7. The imaging system of claim 1, wherein the detector is further configured to determine the reflection coefficient of the object based on a plurality of measured voltages of the reflected signal from the object.

8. An imaging system, comprising:

a network device having a first port, a delta port, a second port, and a summing port, said network device having a signal source providing a very high frequency signal connected to the summing port, and said network device splitting the very high frequency signal into a first signal and second signal;

a reference line connected to the first port of the network device, the reference line receiving the first signal;

a reference load connected to the reference line, the reference load configured to reflect the first signal to produce a first reflected signal transmitted from the reference load along the reference line to the network device, wherein the first reflected signal comprises a reference signal;

an antenna line connected to the second port of the network device, the antenna line receiving the second signal, wherein the antenna line and the reference line are configured to have substantially equal electrical properties and substantially equal electrical lengths;

an antenna connected to the antenna line, the antenna configured to;

transmit the second signal to a remote object,

receive at least one second reflected signal from the remote object, and

transmit the second reflected signal along the antenna line to the network device, wherein the first reflected signal transmitted along the reference line and the second reflected signal transmitted along the antenna line combine within the network device to form a combined signal;

a detector connected to the delta port, said detector sampling the combined signal such that the detector measures a real part of the combined signal; and

a processor configured to execute an imaging algorithm to generate a multi-dimensional profile representative of the object based on a received output voltage proportional to the real part of the reflected signal from the detector;

wherein the detector is configured for measuring a phase difference between the second reflected signal and the reference signal.

9. The imaging system of claim 8, further comprising an isolator connected between the signal source and the summing port.

10. The imaging system of claim 8, wherein the summing port is interchangeable with the delta port.

11. The system of claim 8 wherein the reference line and the antenna line are configured to have substantially the same electrical lengths and substantially the same electrical properties to compensate for delay and phase change from the antenna to the detector with the same delay and phase change from the reference load to the detector.

12. The imaging system of claim 8, wherein the network device is a magic-tee arrangement.

13. The imaging system of claim 8, wherein the phase of the second reflected signal substantially equals the phase of the reference signal and thereby cancels any signal dispersion.

14. The imaging system of claim 13, wherein the detector measures a voltage proportional to an in-phase component of the second reflected signal.

15. A method of imaging a remote object using an antenna, the method comprising:

transmitting a signal from a source via the antenna and incident to the object, the signal source configured to provide an electromagnetic energy source ranging in frequencies up to and including a tetrahertz frequency range;

receiving, by a detector probe, a signal reflected from the object, said detector probe positioned at a distance d from an aperture of the antenna such that the detector probe is phase-referenced to the aperture of the antenna, wherein the detector probe is configured to sample a magnitude of the reflected signal, and wherein d is defined as;

d≦

λ

_g/4, where λ

_g is a guide wavelength at a mid-band frequency of the signal generated by the signal source;

determining a reflection coefficient from the remote object measured at the aperture of the antenna;

receiving a voltage output from the detector probe, wherein the voltage represents a real-valued signal proportional to an in-phase component of the reflected signal from the object; and

generating, by a processor executing an imaging algorithm, a multi-dimensional profile representative of the object based on the received output voltage.