Three-dimensional imaging utilizing low frequency magnetic fields

Patent metadata

Field	Value
Publication number	US-10416244-B2
Application number	US-201715716771-A
Country	US
Kind code	B2
Filing date	Sep 27, 2017
Priority date	Sep 28, 2016
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

A planar sensor array capable of three-dimensional magnetic field sensing is disclosed. The sensor array may be utilized, for example, in connection with security inspections and detection of concealed electronics and contraband. Each sensor pixel may comprise a planar spiral inductor to measure a magnetic field of interest in a first dimension, a first Hall effect sensor to measure the magnetic field of interest in a second dimension, and a second Hall effect sensor to measure the magnetic field of interest in the third dimension.

First claim

What is claimed is:

1. A system for three-dimensional imaging of a magnetic field, the system comprising:
a plurality of sensor pixels arranged in a planar grid, each sensor pixel comprising:
a planar spiral inductor disposed on a first side of a printed circuit board;
a first Hall effect sensor disposed on a second side of the printed circuit board opposite the first side; and
a second Hall effect sensor disposed on the second side of the printed circuit board and orthogonal to the first Hall effect sensor.

2. The system of claim 1 , wherein the plurality of sensor pixels is configured as a 2×8 array.

3. The system of claim 1 , wherein each sensor pixel in the planar grid of sensor pixels further comprises an operational amplifier coupled to the planar spiral inductor, the first Hall effect sensor, and the second Hall effect sensor.

4. The system of claim 3 , wherein the operational amplifier amplifies a signal from the planar spiral inductor by a first magnitude, and wherein the operational amplifier amplifies a signal from the first Hall effect sensor and a signal from the second Hall effect sensor by a second magnitude smaller than the first magnitude.

5. The system of claim 4 , wherein the first magnitude is 100 volts/volt (V/V) and the second magnitude is 10 V/V.

6. The system of claim 1 , further comprising a computing device coupled to each sensor pixel in the planar grid, the computing device configured to record the output of each sensor pixel during operation of the system.

7. The system of claim 1 , wherein the first Hall effect sensor and the second Hall effect sensor comprise identical electronic components.

8. The system of claim 1 , wherein the planar spiral inductor is configured in a rectangular shape.

9. A method for three-dimensional imaging of a magnetic field, the method comprising:
placing a planar array of sensor pixels in a first position; and
moving the planar array between the first position and a second position to image the magnetic field in a three-dimensional space between the first position and the second position,
wherein each sensor pixel in the planar array of sensor pixels comprises:
a planar spiral inductor disposed on a first side of a substrate;
a first Hall effect sensor disposed on a second side of the substrate opposite the first side; and
a second Hall effect sensor disposed on the second side of the substrate.

10. The method of claim 9 , wherein, during operation of a sensor pixel, the inductance of the planar spiral inductor is utilized to measure magnetic flux normal to the planar spiral inductor.

11. The method of claim 10 , wherein, during operation of a sensor pixel, the first Hall effect sensor and the second Hall effect sensor are utilized to measure magnetic flux in the plane of the sensor pixel.

12. The method of claim 11 , wherein each sensor pixel in the planar array of sensor pixels further comprises an operational amplifier coupled to the planar spiral inductor, the first Hall effect sensor, and the second Hall effect sensor.

13. The method of claim 12 , wherein, during operation of a sensor pixel:
the operational amplifier amplifies a signal from the planar spiral inductor by a first magnitude; and
the operational amplifier amplifies a signal from the first Hall effect sensor and a signal from the second Hall effect sensor by a second magnitude smaller than the first magnitude.

14. The method of claim 9 , wherein the moving the planar array between the first position and the second position comprises:
taking a reading from each sensor pixel in the planar array of sensor pixels at the first position;
taking a reading from each sensor pixel in the planar array of sensor pixels at one or more intermediary positions between the first position and the second position; and
taking a reading from each sensor pixel in the planar array of sensor pixels at the second position.

15. The method of claim 9 , wherein each sensor pixel is capable of detecting a magnetic field as small as 10 −3 mT.

16. The method of claim 9 , wherein, during the moving the planar array between the first position and the second position, the output of each sensor pixel is recorded by a computing device.

Assignees

• Allee David R
• Spell Gregory P
• Larsen Brett
• Wilson Anthony M
• Ma Owen C
• Univ Arizona State

Inventors

• Allee David R
• Spell Gregory P
• Larsen Brett
• Wilson Anthony M
• Ma Owen C

Classifications

• G01R33/10 Primary

  Plotting field distribution {; Measuring field distribution} · CPC title

• G01R33/0023

  Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration (G01R33/0017 takes precedence) · CPC title

• G01R33/072

  Constructional adaptation of the sensor to specific applications · CPC title