Abstract

The absence of non-destructive inspection techniques for illicit drugs hidden in mail envelopes has resulted in such drugs being smuggled across international borders freely. We have developed a novel basic technology for terahertz imaging, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis. The spatial distributions of the targets are obtained from terahertz multispectral transillumination images, using absorption spectra measured with a tunable terahertz-wave source. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

© 2003 Optical Society of America

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References

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  1. D. M. Mittleman, G. Gupta, B. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, �??Recent advantages in terahertz imaging,�?? Appl. Phys. B 68, 1085-1094 (1999).
    [CrossRef]
  2. B. Ferguson and X. C. Zhang, �??Materials for terahertz science and technology,�?? Nature Materials 1, 26-33 (2002).
    [CrossRef]
  3. P. H. Siegel, �??Terahertz technology,�?? IEEE T. Microw. Theory Tech. 50, 910-928 (2002).
    [CrossRef]
  4. J. E. Parmeter, D. W. Murray, D. W. Hannum, Guide for the selection of drug detectors for law enforcement applications, NIJ Guide 601-00, (National Institute of Justice, Washington, 2000).
  5. A. Fitzgerald, and J. Chamberlain, �??An introduction to medical imaging with coherent terahertz frequency radiation,�?? Phys. Med. Biol. 47, R67-R84 (2002).
    [CrossRef] [PubMed]
  6. T. Löffler, T. Bauer, K. Siebert, H. G. Roskos, A. Fitzgerald and S. Czasch, �??Terahertz dark-field imaging of biomedical tissue,�?? Opt. Express 9, 616-621 (2001), <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-9-12-616">http://www.opticsexpress.org/abstract.cfm?URI=OPEX-9-12-616</a>
    [CrossRef] [PubMed]
  7. S. Wang, B. Ferguson, C. Mannella, D. Gray, D. Abbott and X.C Zhang, �??Powder Detection Using THz Imaging,�?? in OSA Trends in Optics and Photonics (TOPS) vol. 73, Conference on Lasers and Electro-Optics, OSA Technical Digest, Postconference Edition (Optical Society of America, Washington DC, 2002), pp. 132-133.
  8. Y. Watanabe, K. Kawase, T. Ikari, H. Ito, Y. Ishikawa and H. Minamide, �??Component spatial pattern analysis of chemicals using terahertz spectroscopic imaging,�?? Appl. Phys. Lett., 83, 800-802 (2003).
    [CrossRef]
  9. K. Kawase, J. Shikata and H. Ito, �??Terahertz wave parametric source,�?? J. Phys. D: Appl. Phys. 35, R1-R14 (2002).
    [CrossRef]
  10. S. Kawata, K. Sasaki, and S. Minami, �??Component analysis of spatial and spectral patterns in multispectral images. I. Basis,�?? J. Opt. Soc. Am. A 4, 2101-2106 (1987).
    [CrossRef] [PubMed]

Appl. Phys. B

D. M. Mittleman, G. Gupta, B. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, �??Recent advantages in terahertz imaging,�?? Appl. Phys. B 68, 1085-1094 (1999).
[CrossRef]

Appl. Phys. Lett.

Y. Watanabe, K. Kawase, T. Ikari, H. Ito, Y. Ishikawa and H. Minamide, �??Component spatial pattern analysis of chemicals using terahertz spectroscopic imaging,�?? Appl. Phys. Lett., 83, 800-802 (2003).
[CrossRef]

IEEE T. Microw. Theory Tech.

P. H. Siegel, �??Terahertz technology,�?? IEEE T. Microw. Theory Tech. 50, 910-928 (2002).
[CrossRef]

J. Opt. Soc. Am. A

J. Phys. D: Appl. Phys.

K. Kawase, J. Shikata and H. Ito, �??Terahertz wave parametric source,�?? J. Phys. D: Appl. Phys. 35, R1-R14 (2002).
[CrossRef]

Nature Materials

B. Ferguson and X. C. Zhang, �??Materials for terahertz science and technology,�?? Nature Materials 1, 26-33 (2002).
[CrossRef]

Opt. Express

Phys. Med. Biol.

A. Fitzgerald, and J. Chamberlain, �??An introduction to medical imaging with coherent terahertz frequency radiation,�?? Phys. Med. Biol. 47, R67-R84 (2002).
[CrossRef] [PubMed]

TOPS

S. Wang, B. Ferguson, C. Mannella, D. Gray, D. Abbott and X.C Zhang, �??Powder Detection Using THz Imaging,�?? in OSA Trends in Optics and Photonics (TOPS) vol. 73, Conference on Lasers and Electro-Optics, OSA Technical Digest, Postconference Edition (Optical Society of America, Washington DC, 2002), pp. 132-133.

Other

J. E. Parmeter, D. W. Murray, D. W. Hannum, Guide for the selection of drug detectors for law enforcement applications, NIJ Guide 601-00, (National Institute of Justice, Washington, 2000).

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Figures (5)

Fig. 1.
Fig. 1.

Schematic of THz spectroscopic imaging system using THz wave parametric oscillator (TPO).

Fig. 2.
Fig. 2.

View of the samples. The small polyethylene bags contain from left to right: MDMA, aspirin, and methamphetamine. The bags were placed inside the envelope during imaging. The area indicated by the yellow line represents the imaging target, 20×38mm in size. Since methamphetamine and aspirin are similar in appearance, we used a slightly longer bag for the latter to avoid confusion.

Fig. 3.
Fig. 3.

Seven multispectral images generating a matrix [I].

Fig. 4.
Fig. 4.

Absorption spectra of MDMA (yellow line), methamphetamine (red line), and aspirin (blue line). The corresponding absorption intensity values at the seven frequencies were extracted to obtain the matrix [S].

Fig. 5.
Fig. 5.

Extracted spatial patterns of MDMA (yellow), aspirin (blue), and methamphetamine (red), using Eq. (2). The three drugs are clearly distinguished and corresponding spatial patterns obtained.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

[ I ] = [ S ] [ P ]
[ P ] = ( [ S ] t [ S ] ) 1 [ S ] t [ I ]

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