Claims
- 1. A method for compensating for image distortion, said method comprising:
disposing a sensor having a drive that creates an interrogating field and at least one sense element proximate to a test material surface; measuring response from each sense element at multiple locations; creating an image of the sense element response; compensating for non-uniform sensor responses over the image area.
- 2. The method as claimed in claim 1 wherein the sensor has an array of sense elements.
- 3. The method as claimed in claim 1 wherein the field is magnetic.
- 4. The method as claimed in claim 1 wherein the field is electric.
- 5. The method as claimed in claim 1 wherein the test material may include a hidden object.
- 6. The method as claimed in claim 1 wherein the compensation uses a model for the expected response of the sensor.
- 7. The method as claimed in claim 1 wherein the compensation uses an empirical response.
- 8. The method as claimed in claim 1 wherein the compensation involves dividing the image data by a known response.
- 9. The method as claimed in claim 1 wherein the compensation involves scaling image axes.
- 10. A test structure comprising:
a mobile platform that supports a testing sensor, which includes a drive electrode that creates an interrogating field and at least one sense element to sense response of a test material to the field; means for exciting the drive electrode; means for measuring the sense element response; and means for providing relative motion between the sensor and the platform.
- 11. The test structure as claimed in claim 10 wherein the sensor has an array of sense elements.
- 12. The test structure as claimed in claim 11 wherein the array has the sense elements aligned along a line.
- 13. The test structure as claimed in claim 10 further comprising means of providing relative motion between the drive electrode and sense elements.
- 14. The test structure as claimed in claim 10 further comprising means for adjusting the sensor proximity to the test material surfaced.
- 15. The test structure as claimed in claim 10 wherein the field is magnetic.
- 16. The test structure as claimed in claim 10 wherein the field is electric.
- 17. A test circuit comprising:
a primary winding having at least one linear segment to impose a magnetic field in a test material when driven by an electric current; at least two sense elements positioned parallel to a linear primary winding segment; and a bucking coil proximate to the sense elements and driven by an electric current so that the local magnetic field opposes the imposed field.
- 18. A test circuit as claimed in claim 17 wherein the sensing elements are inductive to sense a time varying magnetic flux.
- 19. A test circuit as claimed in claim 18 wherein the sensing elements are absolute measurement coils.
- 20. A test circuit as claimed in claim 19 wherein the sensing elements are differential measurement coils.
- 21. A test circuit as claimed in claim 17 wherein at least one sense element has a giant magnetoresistive sensor.
- 22. A test circuit as claimed in claim 17 wherein the bucking coil surrounds the sense elements.
- 23. A test circuit as claimed in claim 17 wherein the bucking coil is driven in series with the primary winding.
- 24. A test circuit as claimed in claim 23 wherein the current through the bucking coil is attenuated with passive circuit elements.
- 25. A test circuit as claimed in claim 24 wherein the passive element is a resistor.
- 26. A test circuit as claimed in claim 17 wherein the bucking coil is driven separately from the primary winding.
- 27. A test circuit as claimed in claim 17 wherein the local magnetic field in the vicinity of the sense elements is nulled.
- 28. A test circuit as claimed in claim 17 further comprising a calibration coil located in the vicinity of the sense elements.
- 29. A test circuit as claimed in claim 28 wherein the calibration coil spans the area over the sense elements.
- 30. A method for calibration comprising:
disposing a sensor array comprising at primary winding that creates an imposed magnetic field when driven by an electric current, at least one sense element, a bucking coil for reducing the local magnetic field in the vicinity of the sense element, and a calibration coil that provides a known sense element response; measuring sense element response with the calibration coil alone excited; measuring the sense element response with the primary winding alone excited; and adjusting the measured response to match a known response.
- 31. A method as claimed in claim 30 wherein adjusting the measured response involve determining an offset and scale factor for the response.
- 32. A test circuit comprising:
a primary winding having at least one linear segment to impose a magnetic field in a test material when driven by an electric current; at least one sense element for sensing the response to the imposed field; and means for moving the sense elements relative to the primary winding.
- 33. A test circuit as claimed in claim 32 further comprising a linear array of sense elements parallel to the linear segment of the primary winding.
- 34. A test circuit as claimed in claim 32 wherein the sensing elements are inductive to sense a time varying magnetic flux.
- 35. A test circuit as claimed in claim 34 wherein the sensing elements are absolute measurement coils.
- 36. A test circuit as claimed in claim 34 wherein the sensing elements are differential measurement coils.
- 37. A test circuit as claimed in claim 32 wherein at least one sense element has a giant magnetoresistive sensor.
- 38. A test circuit as claimed in claim 32 further comprising a second primary winding and sense elements that match the geometry and move synchronously with the first primary winding and sense elements.
- 39. A method for determining the volumetric response of a material comprising:
disposing a sensor comprising a primary winding to impose a magnetic field in a test material when driven by an electric current and at least one sense element proximate to the test material; measuring the sense element response over the surface of the test material; subdividing the region of interest in the test material into volume elements; and determining the equivalent source response for each volume element.
- 40. A method as claimed in claim 39 wherein the primary winding has at least one linear segment.
- 41. A method as claimed in claim 40 wherein the sense elements form a array parallel to the linear drive segment.
- 42. A method as claimed in claim 39 wherein the sense elements can move relative to the primary winding.
- 43. A method as claimed in claim 42 wherein measurements are performed at multiple primary winding positions over the test material surface and for multiple sense element array positions relative to each primary winding position.
- 44. A method as claimed in claim 39 further comprising a second primary winding and sense elements that match the geometry and move synchronously with the first primary winding and sense elements.
- 45. A method as claimed in claim 39 wherein the sensing elements are inductive to sense a time varying magnetic flux.
- 46. A method as claimed in claim 45 wherein the sensing elements are absolute measurement coils.
- 47. A method as claimed in claim 45 wherein the sensing elements are differential measurement coils.
- 48. A method as claimed in claim 39 wherein at least one sense element has a giant magnetoresistive sensor.
- 49. A method as claimed in claim 39 wherein the equivalent source is the dipole moment.
- 50. A method as claimed in claim 39 wherein the equivalent source is three orthogonal current loops.
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional Application No. 60/385,930, filed Jun. 4, 2002, U.S. Provisional Application No. 60/468,828, filed May 8, 2003, and U.S. Provisional Application, attorney's docket no. 1884.2022-001, filed May 13, 2003. The entire teachings of the above applications are incorporated herein by reference.
GOVERNMENT SUPPORT
[0002] The invention was supported, in whole or in part, by contract number DACA72-03-C0001 from the SERDP. The Government has certain rights in the invention.
Provisional Applications (3)
|
Number |
Date |
Country |
|
60385930 |
Jun 2002 |
US |
|
60468828 |
May 2003 |
US |
|
60470143 |
May 2003 |
US |