Abstract

We present terahertz (THz) reflective spectroscopic focal-plane imaging of four explosive and bio-chemical materials (2, 4-DNT, Theophylline, RDX and Glutamic Acid) at a standoff imaging distance of 0.4 m. The 2 dimension (2-D) nature of this technique enables a fast acquisition time and is very close to a camera-like operation, compared to the most commonly used point emission-detection and raster scanning configuration. The samples are identified by their absorption peaks extracted from the negative derivative of the reflection coefficient respect to the frequency (-dr/dv) of each pixel. Classification of the samples is achieved by using minimum distance classifier and neural network methods with a rate of accuracy above 80% and a false alarm rate below 8%. This result supports the future application of THz time-domain spectroscopy (TDS) in standoff distance sensing, imaging, and identification.

© 2006 Optical Society of America

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  1. H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
    [Crossref]
  2. 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]
  3. D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, “T-ray tomography,” Opt. Lett. 22, 904–906 (1997).
    [Crossref] [PubMed]
  4. B. Ferguson and X.-C. Zhang, “Materials for terahertz science and technology,” Nat. Mater. 1, 26–33 (2002).
    [Crossref]
  5. D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
    [Crossref]
  6. D. Zimdars, J. Valdmanis, J. White, and G. Stuk, “Time domain terahertz detection of flaws within space shuttle sprayed on foam insulation,” CLEO, CThN4 (2004).
  7. D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
    [Crossref]
  8. R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
    [Crossref] [PubMed]
  9. Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
    [Crossref]
  10. M. K. Choi, A. Bettermann, and D. W. van der Weide, “Potential for detection of explosive and biological hazards with electronic terahertz systems,” Phil. Trans. R. Soc. Lond. A 362, 337–349 (2004).
    [Crossref]
  11. K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
    [Crossref]
  12. M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
    [Crossref]
  13. F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
    [Crossref]
  14. H. Liu, “Terahertz spectroscopy for chemical and biological sensing applications”, Ph.D. thesis (2006).
  15. D. Arnone, “Terahertz pulsed imaging and spectroscopy for chemical detection and security,” The Joint 30th International Conference on Infrared and Millimeter Waves,  1, 198 (2005).
    [Crossref]
  16. D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
    [Crossref]
  17. H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
    [Crossref]
  18. Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
    [Crossref]
  19. Q. Wu, T. Hewitt, and X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
    [Crossref]
  20. M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
    [Crossref]
  21. R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
    [Crossref]
  22. F. Ferguson, S. Wang, D. Gray, D. Abbot, and X.-C. Zhang, “T-ray computed tomography,” Opt. Lett. 27, 1312–1314 (2002).
    [Crossref]
  23. National Research Council of the National Academies, “Existing and potential standoff explosives detection techniques,” (National Academies Press2004).
  24. J. Jackson, Classical Electrodynamics, (Wiley & Sons, New York, 1975).
  25. E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
    [Crossref]
  26. K. Yamamoto, A. Masui, and H. Ishida, “Kramers-Kronig analysis of infrared reflection spectra with perpendicular polarization,” Appl. Opt. 33, 6285–6293 (1994).
    [Crossref] [PubMed]
  27. F. Wooten, Optical properties of solids, (Academic New York, 1972).
  28. H. Zhong, “Terahertz wave reflective sensing and imaging,” Ph.D. thesis (2006).
  29. E. Hecht, Optics, (Addison Wesley Longman1998).
  30. D. Michie, D. Spiegelhalter, and C. Taylor, Machine learning, neural and statistical classification, (Ellis Horwood, 1994).
  31. L. Zheng and X. He, “Classification techniques in pattern recognition,” WSCG, conference proceedings, ISBN 80-903100-8-7 (2005).
  32. J. Edward Jackson, A user’s Guide to principal components, and subspaces, (Wiley & Sons, New York, 1991).
    [Crossref]
  33. B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
    [Crossref]
  34. G. Seber, Multivariate observations, (Wiley & Sons, New York, 1984).
    [Crossref]
  35. Z. Bian and X. Zhang, Pattern recognition, (Tsinghua University Press, Beijing, 1999).
  36. F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
    [Crossref]
  37. T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
    [Crossref]
  38. J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
    [Crossref]
  39. B. Ferguson, “Three-dimensional T-ray inspection systems,” Ph.D. thesis (2003).

2005 (6)

D. Arnone, “Terahertz pulsed imaging and spectroscopy for chemical detection and security,” The Joint 30th International Conference on Infrared and Millimeter Waves,  1, 198 (2005).
[Crossref]

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
[Crossref]

Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
[Crossref]

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

2004 (6)

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

M. K. Choi, A. Bettermann, and D. W. van der Weide, “Potential for detection of explosive and biological hazards with electronic terahertz systems,” Phil. Trans. R. Soc. Lond. A 362, 337–349 (2004).
[Crossref]

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

2003 (7)

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
[Crossref]

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

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]

R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
[Crossref]

2002 (2)

B. Ferguson and X.-C. Zhang, “Materials for terahertz science and technology,” Nat. Mater. 1, 26–33 (2002).
[Crossref]

F. Ferguson, S. Wang, D. Gray, D. Abbot, and X.-C. Zhang, “T-ray computed tomography,” Opt. Lett. 27, 1312–1314 (2002).
[Crossref]

1999 (1)

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

1998 (1)

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

1997 (1)

1996 (1)

Q. Wu, T. Hewitt, and X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[Crossref]

1994 (1)

Abbot, D.

Abbott, D.

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

Altan, H.

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Arnone, D.

D. Arnone, “Terahertz pulsed imaging and spectroscopy for chemical detection and security,” The Joint 30th International Conference on Infrared and Millimeter Waves,  1, 198 (2005).
[Crossref]

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Baraniuk, R. G.

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

Barat, R.

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

Bettermann, A.

M. K. Choi, A. Bettermann, and D. W. van der Weide, “Potential for detection of explosive and biological hazards with electronic terahertz systems,” Phil. Trans. R. Soc. Lond. A 362, 337–349 (2004).
[Crossref]

Bian, Z.

Z. Bian and X. Zhang, Pattern recognition, (Tsinghua University Press, Beijing, 1999).

Boivin, L.

Bykhovskaia, M.

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

Chen, M.

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Chen, Y.

H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
[Crossref]

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Chernovsky, A.

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

Choi, M. K.

M. K. Choi, A. Bettermann, and D. W. van der Weide, “Potential for detection of explosive and biological hazards with electronic terahertz systems,” Phil. Trans. R. Soc. Lond. A 362, 337–349 (2004).
[Crossref]

Cluff, J. A.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Cole, B.

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Cole, B. E.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Deng, Y.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Edward Jackson, J.

J. Edward Jackson, A user’s Guide to principal components, and subspaces, (Wiley & Sons, New York, 1991).
[Crossref]

Federici, J.

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

Federici, J. F.

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Ferguson, B.

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

B. Ferguson and X.-C. Zhang, “Materials for terahertz science and technology,” Nat. Mater. 1, 26–33 (2002).
[Crossref]

B. Ferguson, “Three-dimensional T-ray inspection systems,” Ph.D. thesis (2003).

Ferguson, F.

Fichter, G.

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

Fitch, M. J.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Fitzgerald, A. J.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Fukushima, M, K.

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

Gary, D.

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Gelmont, B.

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

Globus, T.

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

Gray, D.

Gupta, M.

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

Hangyo, M.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Hattori, T.

R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
[Crossref]

He, X.

L. Zheng and X. He, “Classification techniques in pattern recognition,” WSCG, conference proceedings, ISBN 80-903100-8-7 (2005).

Hecht, E.

E. Hecht, Optics, (Addison Wesley Longman1998).

Hewitt, T.

Q. Wu, T. Hewitt, and X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[Crossref]

Huang, F.

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Hunsche, S.

Ikari, T.

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]

Ikeda, T.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Ino, Y.

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

Ishida, H.

Ishikawa, Y.

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]

Ito, H.

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]

Jackson, J.

J. Jackson, Classical Electrodynamics, (Wiley & Sons, New York, 1975).

Jacobsen, R. H.

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

Kawase, K.

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

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]

Kemp, M. C.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Koch, M.

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

Koide, K.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Kuwata-Gonokami, M.

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

Linfield, E.

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Liu, H.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

H. Liu, “Terahertz spectroscopy for chemical and biological sensing applications”, Ph.D. thesis (2006).

Madaras, E.

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

Masui, A.

Matsushita, A.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Michie, D.

D. Michie, D. Spiegelhalter, and C. Taylor, Machine learning, neural and statistical classification, (Ellis Horwood, 1994).

Mickan, S.

J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
[Crossref]

Minami, Y.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Minamide, H.

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]

Mittleman, D. M.

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, “T-ray tomography,” Opt. Lett. 22, 904–906 (1997).
[Crossref] [PubMed]

Miyamaru, F.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Neelamani, R.

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

Newnham, D.

Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
[Crossref]

Nuss, M. C.

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

D. M. Mittleman, S. Hunsche, L. Boivin, and M. C. Nuss, “T-ray tomography,” Opt. Lett. 22, 904–906 (1997).
[Crossref] [PubMed]

Ohta, K.

R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
[Crossref]

Oliveira, F.

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

Osiander, R.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Otani, C.

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

Peiponen, K.-E.

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

Pepper, M.

Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
[Crossref]

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Pye, R.

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Redo, A.

H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
[Crossref]

Reightler, T. Y. R.

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

Rudd, J. V.

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

Rungsawang, R.

R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
[Crossref]

Samuels, A.

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

Schauki, D.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Schulkin, B.

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

Seber, G.

G. Seber, Multivariate observations, (Wiley & Sons, New York, 1984).
[Crossref]

Shen, Y.

Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
[Crossref]

Shimano, R.

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

Shur, M.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Spiegelhalter, D.

D. Michie, D. Spiegelhalter, and C. Taylor, Machine learning, neural and statistical classification, (Ellis Horwood, 1994).

Stuk, G.

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

D. Zimdars, J. Valdmanis, J. White, and G. Stuk, “Time domain terahertz detection of flaws within space shuttle sprayed on foam insulation,” CLEO, CThN4 (2004).

Svirko, Y. P.

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

Taday, P.

Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
[Crossref]

Taday, P. F.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Tani, M.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Tanner, D. B.

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Tatsuno, M.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Taylor, C.

D. Michie, D. Spiegelhalter, and C. Taylor, Machine learning, neural and statistical classification, (Ellis Horwood, 1994).

Tribe, W. R.

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Tukamoto, K.

R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
[Crossref]

Usami, M.

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

Valdmanis, J.

D. Zimdars, J. Valdmanis, J. White, and G. Stuk, “Time domain terahertz detection of flaws within space shuttle sprayed on foam insulation,” CLEO, CThN4 (2004).

van der Weide, D. W.

M. K. Choi, A. Bettermann, and D. W. van der Weide, “Potential for detection of explosive and biological hazards with electronic terahertz systems,” Phil. Trans. R. Soc. Lond. A 362, 337–349 (2004).
[Crossref]

Vartiainen, E. M.

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

Veksler, D.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Wallace, V.

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Wang, S.

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

F. Ferguson, S. Wang, D. Gray, D. Abbot, and X.-C. Zhang, “T-ray computed tomography,” Opt. Lett. 27, 1312–1314 (2002).
[Crossref]

Watanabe, Y.

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]

Werbos, L.

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

White, J.

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

D. Zimdars, J. Valdmanis, J. White, and G. Stuk, “Time domain terahertz detection of flaws within space shuttle sprayed on foam insulation,” CLEO, CThN4 (2004).

Williamson, S.

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

Woodward, R.

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

Woolard, D.

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

Wooten, F.

F. Wooten, Optical properties of solids, (Academic New York, 1972).

Wu, Q.

Q. Wu, T. Hewitt, and X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[Crossref]

Xie, X.

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

Xu, J.

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
[Crossref]

Yamaguchi, M.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Yamamoto, K.

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

K. Yamamoto, A. Masui, and H. Ishida, “Kramers-Kronig analysis of infrared reflection spectra with perpendicular polarization,” Appl. Opt. 33, 6285–6293 (1994).
[Crossref] [PubMed]

Yamashita, M.

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

Yuan, T.

J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
[Crossref]

Zhang, X.

Z. Bian and X. Zhang, Pattern recognition, (Tsinghua University Press, Beijing, 1999).

Zhang, X. -C.

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

Zhang, X.-C.

H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
[Crossref]

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
[Crossref]

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

B. Ferguson and X.-C. Zhang, “Materials for terahertz science and technology,” Nat. Mater. 1, 26–33 (2002).
[Crossref]

F. Ferguson, S. Wang, D. Gray, D. Abbot, and X.-C. Zhang, “T-ray computed tomography,” Opt. Lett. 27, 1312–1314 (2002).
[Crossref]

Q. Wu, T. Hewitt, and X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[Crossref]

Zheng, L.

L. Zheng and X. He, “Classification techniques in pattern recognition,” WSCG, conference proceedings, ISBN 80-903100-8-7 (2005).

Zhong, H.

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
[Crossref]

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

H. Zhong, “Terahertz wave reflective sensing and imaging,” Ph.D. thesis (2006).

Zimdars, D.

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

D. Zimdars, J. Valdmanis, J. White, and G. Stuk, “Time domain terahertz detection of flaws within space shuttle sprayed on foam insulation,” CLEO, CThN4 (2004).

Appl. Opt. (1)

Appl. Phys. B (2)

D. M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V. Rudd, and M. Koch, “Recent advances in terahertz imaging,” Appl. Phys. B 68, 1085–1094 (1999).
[Crossref]

D. M. Mittleman, R. H. Jacobsen, R. Neelamani, R. G. Baraniuk, and M. C. Nuss, “Gas sensing using terahertz time-domain spectroscopy,” Appl. Phys. B 67, 379–390 (1998).
[Crossref]

Appl. Phys. Lett. (4)

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]

F. Huang, B. Schulkin, H. Altan, J. F. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen, and D. B. Tanner, “Terahertz study of 1,3,5-trinitro-s-triazine by time-domain and Fourier transform infrared spectroscopy,” Appl. Phys. Lett. 85, 5535–5537 (2004).
[Crossref]

Q. Wu, T. Hewitt, and X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[Crossref]

M. Usami, M. Yamashita, M, K. Fukushima, C. Otani, and K. Kawase, “Terahertz wideband spectroscopic imaging based on two-dimensional electro-optic sampling technique,” Appl. Phys. Lett. 86, 141109-1–3 (2005).
[Crossref]

Chin. Phys. Lett. (1)

J. Xu, T. Yuan, S. Mickan, and X.-C. Zhang, “Limit of spectral resolution in terahertz time-domain spectroscopy,” Chin. Phys. Lett. 20, 1266–1268 (2003).
[Crossref]

IEEE Sens. J. (1)

H. Zhong, J. Xu, X. Xie, T. Y. R. Reightler, E. Madaras, and X.-C. Zhang, “Nondestructive defect identification with terahertz time-of-flight tomography,” IEEE Sens. J. 5, 203–208 (2005).
[Crossref]

International Journal of High Speed Electronics and Systems (1)

T. Globus, D. Woolard, M. Bykhovskaia, B. Gelmont, L. Werbos, and A. Samuels, “THz-frequency spectroscopic sensing of DNA and related biological materials,” International Journal of High Speed Electronics and Systems,  13, 903–936 (2003).
[Crossref]

J. Appl. Phys. (1)

E. M. Vartiainen, Y. Ino, R. Shimano, M. Kuwata-Gonokami, Y. P. Svirko, and K.-E. Peiponen, “Numerical phase correction method for terahertz time-domain reflection spectroscopy,” J. Appl. Phys. 96, 4171–4175 (2004).
[Crossref]

J. Invest. Dermatol. (1)

R. Woodward, V. Wallace, R. Pye, B. Cole, D. Arnone, E. Linfield, and M. Pepper, “Terahertz pulse imaging of ex vivo basal cell carcinoma samples,” J. Invest. Dermatol. 120, 72–78 (2003).
[Crossref] [PubMed]

J. Phys. D: Appl. Phys. (1)

R. Rungsawang, K. Ohta, K. Tukamoto, and T. Hattori, “Ring formation of focused half-cycle terahertz pulses,” J. Phys. D: Appl. Phys. 36229–235 (2003).
[Crossref]

Jpn. J. Appl. Phys. (1)

K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, and Y. Minami, “Noninvasive inspection of C-4 explosive in mails by terahertz time-domain spectroscopy,” Jpn. J. Appl. Phys. 43, n 3B, L414–417 (2004).
[Crossref]

Nat. Mater. (1)

B. Ferguson and X.-C. Zhang, “Materials for terahertz science and technology,” Nat. Mater. 1, 26–33 (2002).
[Crossref]

Opt. Lett. (2)

Phil. Trans. R. Soc. Lond. A (1)

M. K. Choi, A. Bettermann, and D. W. van der Weide, “Potential for detection of explosive and biological hazards with electronic terahertz systems,” Phil. Trans. R. Soc. Lond. A 362, 337–349 (2004).
[Crossref]

Proc. SPIE (4)

M. C. Kemp, P. F. Taday, B. E. Cole, J. A. Cluff, A. J. Fitzgerald, and W. R. Tribe, “Security applications of terahertz technology,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 44–52 (2003).
[Crossref]

Y. Chen, H. Liu, Y. Deng, D. Veksler, M. Shur, X. -C. Zhang, D. Schauki, M. J. Fitch, and R. Osiander, “Spectroscopic characterization of explosives in the far infrared region,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 1–8 (2004).
[Crossref]

F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, “Analysis of THz spectral images of explosives and bio-agents using trained neural networks,” in Terahertz for Military and Security Applications II, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5411, 45 (2004).
[Crossref]

B. Ferguson, S. Wang, H. Zhong, D. Abbott, and X.-C. Zhang, “Powder detection with T-ray imaging,” in Terahertz for Military and Security Applications, R. J. Hwu and D. L. Woolard, eds., Proc. SPIE 5070, 7–16 (2003).
[Crossref]

Semicond. Sci. Technol. (1)

Y. Shen, P. Taday, D. Newnham, and M. Pepper, “Chemical mapping using reflection terahertz pulsed imaging,” Semicond. Sci. Technol. 20, S254–257 (2005).
[Crossref]

The Joint 30th International Conference on Infrared and Millimeter Waves (1)

D. Arnone, “Terahertz pulsed imaging and spectroscopy for chemical detection and security,” The Joint 30th International Conference on Infrared and Millimeter Waves,  1, 198 (2005).
[Crossref]

D. Zimdars, J. White, G. Stuk, A. Chernovsky, G. Fichter, and S. Williamson, “Large area high speed time domain THz imager for security and nondestructive evaluation imaging,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 5–6 (2005).
[Crossref]

H. Zhong, A. Redo, Y. Chen, and X.-C. Zhang, “Standoff distance detection of explosive materials with THz waves,” the Joint 30th International Conference on Infrared and Millimeter Waves,  1, 42–3 (2005).
[Crossref]

Other (13)

H. Liu, “Terahertz spectroscopy for chemical and biological sensing applications”, Ph.D. thesis (2006).

D. Zimdars, J. Valdmanis, J. White, and G. Stuk, “Time domain terahertz detection of flaws within space shuttle sprayed on foam insulation,” CLEO, CThN4 (2004).

G. Seber, Multivariate observations, (Wiley & Sons, New York, 1984).
[Crossref]

Z. Bian and X. Zhang, Pattern recognition, (Tsinghua University Press, Beijing, 1999).

B. Ferguson, “Three-dimensional T-ray inspection systems,” Ph.D. thesis (2003).

National Research Council of the National Academies, “Existing and potential standoff explosives detection techniques,” (National Academies Press2004).

J. Jackson, Classical Electrodynamics, (Wiley & Sons, New York, 1975).

F. Wooten, Optical properties of solids, (Academic New York, 1972).

H. Zhong, “Terahertz wave reflective sensing and imaging,” Ph.D. thesis (2006).

E. Hecht, Optics, (Addison Wesley Longman1998).

D. Michie, D. Spiegelhalter, and C. Taylor, Machine learning, neural and statistical classification, (Ellis Horwood, 1994).

L. Zheng and X. He, “Classification techniques in pattern recognition,” WSCG, conference proceedings, ISBN 80-903100-8-7 (2005).

J. Edward Jackson, A user’s Guide to principal components, and subspaces, (Wiley & Sons, New York, 1991).
[Crossref]

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Figures (9)

Fig. 1.
Fig. 1.

The absorption coefficient κ and -dr/dν of RDX. Both curves show the absorption peak around 0.82 THz and 1.05 THz, which are indicated by arrows.

Fig. 2.
Fig. 2.

Experimental-set up of THz reflective spectroscopic focal-plane imaging system.

Fig. 3.
Fig. 3.

The extinction coefficient κ of RDX, Theophylline, 2, 4-DNT, and Glutamic Acid measured by transmission THz-TDS in nitrogen purged cell. Data is shifted for clarity. The arrows indicate the absorption peaks of each target.

Fig. 4.
Fig. 4.

Time domain waveform (top) and spectrum (bottom) of the reference THz wave (averaged over all pixels).

Fig. 5.
Fig. 5.

Optical picture of 2, 4-DNT, Theopylline, RDX, Glutamic Acid and glass sample target.

Fig. 6.
Fig. 6.

THz peak amplitude image of 2, 4-DNT, Theophylline RDX, Glutamic Acid and glass. Identification of the samples is not possible in this image.

Fig. 7.
Fig. 7.

-dr/dv of RDX, Theophylline, 2, 4-DNT, Glutamic Acid and glass from five randomly selected pixels on each sample image. The arrows indicate the absorption peaks. Three absorption peaks of RDX, one of 2, 4-DNT and one of Glutamic Acid are located by comparing with Fig 6.2. No significant absorption features are found in Theophylline’s plot.

Fig. 8.
Fig. 8.

The images of the sample targets formed by integrating the peak area around (a) 0.82 THz; (b) 0.96 THz; (c) 1.08 THz and (d) 1.21 THz, with a width of 0.15 THz. Except for the image at 0.96 THz, which is supposed to be the absorption peak location of Theophylline, all three other samples can be identified at the images of their corresponding absorption peak frequencies.

Fig. 9.
Fig. 9.

Histogram of the spectroscopic image at 1.21 THz on Fig. 8 (d). The pixel value is normalized from 1 to 10. The position of the peak on the left Ifloor represents the pixel value of the background, whereas the position of the peak on the right Ipeak indicates the pixel value of the foreground, which is the sample being identified.

Tables (3)

Tables Icon

Table 1. Contrast of each image on Fig. 8. The image at 0.82 THz has the highest contrast because the extinction coefficient κ of RDX is measured to be the highest among the four. The image at 0.96 THz has zero contrast resulting from the single normal distribution on its histogram. The failure to identify any absorption feature at 0.96 THz image is due to insufficient dynamic range of the imaging system.

Tables Icon

Table 2. Positive (P), negative (W) and false (F) identification percentage of the classification using the first derivative of reflective coefficient -dr/dv.

Tables Icon

Table 3. Positive (P), negative (W) and false (F) identification rate using both A and B criteria.

Equations (7)

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

r ˜ = E 2 E 1 = n ˜ 1 n ˜ + 1 = ( n 1 ) + i κ ( n + 1 ) + i κ = R e i ϕ
n = 1 + R 1 + R 2 R cos ϕ κ = 2 R sin ϕ 1 + R 2 R cos ϕ
v 1 v 2 dr dv dv = r v 2 r v 1 = Δ r
C = ( I peak I floor ) ( I peak + I floor )
d i x = ( x μ i ) T i 1 ( x μ i )
P i = r i N i , W i = t i N i , N i = r i + t i + o i , F i = u i N , N = i N i
Δ r δ r > SNR D > SNR · r Δ r

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