Security screening and inspection based on broadband electromagnetic holographic imaging
First Claim
1. A system of security screening a body and attached object, comprising:
- a portal including at least one transmitter coil and at least one receiver coil, wherein said portal is configured to accommodate said body and attached object passing therethrough;
wherein said transmitter coil is configured to generate a broadband electromagnetic field comprising a frequency domain electromagnetic field and/or time domain electromagnetic field that propagates through said body and attached object and interacts with said body and attached object to result in a scattered electromagnetic field; and
wherein said receiver coil is configured to record said scattered electromagnetic field; and
a computer configured to simulate a first background electromagnetic field existing within said portal when there is no body and attached object within said portal, to compute a first backscattering electromagnetic field obtainable by transmitting said scattered electromagnetic field from said receiver coil, to produce an image of electric conductivity and/or dielectric permittivity of said body and attached object, and to determine at least one characteristic of the attached object;
wherein the computer is configured to produce the image by;
calculating a second background electromagnetic field in response to said first background electromagnetic field;
calculating a residual electromagnetic field between the second background electromagnetic field and the first backscattering electromagnetic field;
calculating a second backscattering field for the residual electromagnetic field by simulating illumination of the updated background medium; and
constructing updated volume images on the basis of updated cross power spectrum or cross correlation functions between said first background field and said second backscattering field.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of security screening and inspection of people in airlines, ships, or secured buildings, involves placing an array of transmitters and receivers in operational association with the medium. The transmitters generate a broad band harmonic (frequency domain) or pulse (time domain) primary electromagnetic field (EM) field, including the lower frequency portions of the EM spectrum, whose propagation is typically characterized by the diffusion phenomena, or by the combination of the diffusion and wave phenomena. The primary field propagates through and interacts with the examined person and any objects carried by the person to produce a scattered field, which is recorded by the receivers. The scattered EM field components measured by the receivers are applied as an artificial EM field to generate a backscattering EM field. Cross power spectra of the primary and backscattering fields (in the frequency domain) or cross correlation between these fields (in the time domain) produce a numerical reconstruction of an EM hologram. The desired properties of the person, including the properties of any objects carried by the person, such as conductivity or dielectric permittivity, are then derived from this hologram.
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Citations
44 Claims
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1. A system of security screening a body and attached object, comprising:
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a portal including at least one transmitter coil and at least one receiver coil, wherein said portal is configured to accommodate said body and attached object passing therethrough;
wherein said transmitter coil is configured to generate a broadband electromagnetic field comprising a frequency domain electromagnetic field and/or time domain electromagnetic field that propagates through said body and attached object and interacts with said body and attached object to result in a scattered electromagnetic field; and
wherein said receiver coil is configured to record said scattered electromagnetic field; anda computer configured to simulate a first background electromagnetic field existing within said portal when there is no body and attached object within said portal, to compute a first backscattering electromagnetic field obtainable by transmitting said scattered electromagnetic field from said receiver coil, to produce an image of electric conductivity and/or dielectric permittivity of said body and attached object, and to determine at least one characteristic of the attached object; wherein the computer is configured to produce the image by; calculating a second background electromagnetic field in response to said first background electromagnetic field; calculating a residual electromagnetic field between the second background electromagnetic field and the first backscattering electromagnetic field; calculating a second backscattering field for the residual electromagnetic field by simulating illumination of the updated background medium; and constructing updated volume images on the basis of updated cross power spectrum or cross correlation functions between said first background field and said second backscattering field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system of security screening a body and attached object, comprising:
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a portal including at least one transmitter coil and at least one receiver coil, wherein said portal is configured to accommodate said body and attached object passing therethrough;
wherein said transmitter coil is configured to generate a broadband electromagnetic field comprising a frequency domain electromagnetic field and/or time domain electromagnetic field that propagates through said body and attached object and interacts with said body and attached object to result in a scattered electromagnetic field; and
wherein said receiver coil is configured to record said scattered electromagnetic field;a computer configured to simulate a first background electromagnetic field existing within said portal when there is no body and attached object within said portal, to compute a first backscattering electromagnetic field obtainable by transmitting said scattered electromagnetic field from said receiver coil, to produce an image of electric conductivity and/or dielectric permittivity of said body and attached object, and to determine at least one characteristic of the attached object; wherein said computer is configured to produce said image iteratively by; calculating a second background electromagnetic field in response to said first background electromagnetic field with a previously obtained complex conductivity; calculating a residual electromagnetic field between the second background electromagnetic field and the first backscattering electromagnetic field; calculating a second backscattering field for the residual electromagnetic field by simulating illumination of the updated background medium with electric and magnetic currents equivalent to those of the updated residual electromagnetic field recorded at the location of the receivers; and constructing updated volume images of anomalous conductivity {tilde over (σ
)}a(n)(r) and of anomalous permittivity ∈
a(n)(r) on the basis of updated cross power spectrum or cross correlation functions between said first background field and said second backscattering field, using regularization procedures. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 37, 38, 39, 40, 41, 42, 43, 44)
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23. A method of security screening a body and attached object, comprising:
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providing a portal adapted to passably receive said body and attached object, wherein said portal includes at least one transmitter coil and at least one receiver coil, wherein said transmitter coil is adapted to generate a broadband electromagnetic field comprising a frequency domain electromagnetic field and/or a time domain electromagnetic field that propagates through said body and attached object and that interacts with said body and attached object to result in a scattered electromagnetic field, and wherein said receiver coil is adapted to record said scattered electromagnetic field; simulating a first background electromagnetic field existing within said portal when there is no body and attached object within said portal; computing a first backscattering electromagnetic field obtainable by transmitting the scattered electromagnetic field from said receiver coil; producing an image of electric conductivity and/or dielectric permittivity of said body and attached object; calculating a second background electromagnetic field in response to said first background electromagnetic field; calculating a residual electromagnetic field between the second background electromagnetic field and the first backscattering electromagnetic field; calculating a second backscattering field for the residual electromagnetic field by simulating illumination of the updated background medium; and constructing updated volume images on the basis of updated cross power spectrum or cross correlation functions between said first background field and said second backscattering field; and determining at least one characteristic of said attached object. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method of security screening a body and attached object, comprising:
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providing a portal adapted to passably receive said body and attached object, wherein said portal includes at least one transmitter coil and at least one receiver coil, wherein said transmitter coil is adapted to generate a broadband electromagnetic field comprising a frequency domain electromagnetic field and/or a time domain electromagnetic field that propagates through said body and attached object and that interacts with said body and attached object to result in a scattered electromagnetic field, and wherein said receiver coil is adapted to record said scattered electromagnetic field; simulating a first background electromagnetic field existing within said portal when there is no body and attached object within said portal; computing a first backscattering electromagnetic field obtainable by transmitting the scattered electromagnetic field from said receiver coil; producing an image of electric conductivity and/or dielectric permittivity of said body and attached object; determining at least one characteristic of said attached object; calculating a second background electromagnetic field in response to said first background electromagnetic field with a previously obtained complex conductivity; calculating a residual electromagnetic field between the second background electromagnetic field and the first backscattering electromagnetic field; calculating a second backscattering field for the residual electromagnetic field by simulating illumination of the updated background medium with electric and magnetic currents equivalent to those of the updated residual electromagnetic field recorded at the location of the receivers; and constructing updated volume images of anomalous conductivity {tilde over (σ
)}a(n)(r) and of anomalous permittivity ∈
a(n)(r) on the basis of updated cross power spectrum or cross correlation functions between said first background field and said second backscattering field, using regularization procedures. - View Dependent Claims (35, 36)
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Specification