
Proceedings Paper
Package inspection using inverse diffractionFormat | Member Price | Non-Member Price |
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Paper Abstract
More efficient cost-effective hand-held methods of inspecting packages without opening them are in demand for
security. Recent new work in TeraHertz sources,1 millimeter waves, presents new possibilities. Millimeter waves
pass through cardboard and styrofoam, common packing materials, and also pass through most materials except
those with high conductivity like metals which block light and are easily spotted. Estimating refractive index
along the path of the beam through the package from observations of the beam passing out of the package
provides the necessary information to inspect the package and is a nonlinear problem. So we use a generalized
linear inverse technique that we first developed for finding oil by reflection in geophysics.2 The computation
assumes parallel slices in the packet of homogeneous material for which the refractive index is estimated. A
beam is propagated through this model in a forward computation. The output is compared with the actual
observations for the package and an update computed for the refractive indices. The loop is repeated until
convergence. The approach can be modified for a reflection system or to include estimation of absorption.
Paper Details
Date Published: 3 September 2008
PDF: 6 pages
Proc. SPIE 7072, Optics and Photonics for Information Processing II, 70720H (3 September 2008); doi: 10.1117/12.796109
Published in SPIE Proceedings Vol. 7072:
Optics and Photonics for Information Processing II
Abdul Ahad Sami Awwal; Khan M. Iftekharuddin; Bahram Javidi, Editor(s)
PDF: 6 pages
Proc. SPIE 7072, Optics and Photonics for Information Processing II, 70720H (3 September 2008); doi: 10.1117/12.796109
Show Author Affiliations
Alastair D. McAulay, Lehigh Univ. (United States)
Published in SPIE Proceedings Vol. 7072:
Optics and Photonics for Information Processing II
Abdul Ahad Sami Awwal; Khan M. Iftekharuddin; Bahram Javidi, Editor(s)
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