Apparatus and methods for measuring permeability and conductivity in materials using multiple wavenumber magnetic interrogations
First Claim
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1. An apparatus for measuring a property of a material, the apparatus comprising:
- an array of electromagnetic elements capable of imposing a magnetic field in a material and sensing a resulting electromagnetic response;
a wavenumber controller connected to said array for applying a current to subsets of said electromagnetic elements and thereby defining fundamental wavenumbers associated with said imposed magnetic field in the material; and
an analyzer connected to said wavenumber controller, including means for comparing the resulting responses sensed by said electromagnetic array at different wavenumbers to predictions in order to derive a spatial profile of complex permeability or conductivity in the material.
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Abstract
Devices and analytical techniques are disclosed for measuring spatial profiles of complex permeability and conductivity of a material by multiple wavenumber interrogations. Coil array structures are disclosed which define a number of different fundamental wavelengths (or wavenumbers). Spatially periodic interrogation signals (of temporal frequency "ω") from the coil array structures are attenuated by varying degrees in the material undergoing analysis, depending on the wavenumber ("k"), thereby permitting the derivation of composite complex permeability/conductivity profile.
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Citations
20 Claims
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1. An apparatus for measuring a property of a material, the apparatus comprising:
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an array of electromagnetic elements capable of imposing a magnetic field in a material and sensing a resulting electromagnetic response; a wavenumber controller connected to said array for applying a current to subsets of said electromagnetic elements and thereby defining fundamental wavenumbers associated with said imposed magnetic field in the material; and an analyzer connected to said wavenumber controller, including means for comparing the resulting responses sensed by said electromagnetic array at different wavenumbers to predictions in order to derive a spatial profile of complex permeability or conductivity in the material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for measuring the properties of a material, the method comprising:
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disposing an array of electromagnetic elements in proximity to a material, the electromagnetic elements being adapted to impose a magnetic field in the material and sense a resulting electromagnetic response; interrogating the material with a magnetic field at multiple wavelengths defines by subsets of said electromagnetic elements; sensing the resulting electromagnetic response at multiple wavelengths; and
deriving a spatial profile of at least one property of the material from said electromagnetic response. - View Dependent Claims (11, 12)
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13. A method for measuring the properties of a material, the method comprising:
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disposing an array of electromagnetic elements in proximity to a material, the electromagnetic elements being adapted to impose a magnetic field in the material and sense a resulting electromagnetic response; interrogating the material with a magnetic field at multiple wavelengths defined by subsets of said electromagnetic elements; sensing the resulting electromagnetic response at multiple wavelengths to derive a spatial profile of at least one property of the material; measuring the gain at the shortest wavelength to derive a profile estimation for a first material layer; and measuring the gain with at least one longer wavelength to derive a profile estimation for a subsequent material layer. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification