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Security screening and inspection based on broadband electromagnetic holographic imaging

  • US 7,550,969 B2
  • Filed: 04/30/2002
  • Issued: 06/23/2009
  • Est. Priority Date: 06/26/1997
  • Status: Expired due to Term
First Claim
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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.

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