Abstract

Real-time imaging in the terahertz (THz) spectral range was achieved using a milliwatt-scale, 2.8THz quantum cascade laser and an uncooled, 160×120  pixel microbolometer camera modified with Picarin optics. Noise equivalent temperature difference of the camera in the 15THz frequency range was estimated to be at least 3K, confirming the need for external THz illumination when imaging in this frequency regime. Despite the appearance of fringe patterns produced by multiple diffraction effects, single-frame and extended video imaging of obscured objects show high-contrast differentiation between metallic and plastic materials, supporting the viability of this imaging approach for use in future security screening applications.

© 2008 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]

2007 (1)

B. N. Behnken, M. Lowe, G. Karunasiri, D. Chamberlin, P. R. Robrish, and J. Faist, Proc. SPIE 6549, 65490C (2007).
[CrossRef]

2006 (1)

A. W. M. Lee, B. S. Williams, Q. Hu, and J. L. Reno, IEEE Photonics Technol. Lett. 18, 1415 (2006).
[CrossRef]

2005 (2)

J. F. Federici, D. Gary, R. Barat, and D. Zimdars, Proc. SPIE 5781, 75 (2005).
[CrossRef]

A. W. M. Lee and Q. Hu, Opt. Lett. 30, 2563 (2005).
[CrossRef] [PubMed]

2004 (2)

D. A. Zimdars and J. S. White, Proc. SPIE 5411, 78 (2004).
[CrossRef]

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, M. A. Celis, and E. R. Brown, Appl. Phys. Lett. 85, 519 (2004).
[CrossRef]

2003 (1)

J. Faist, L. Ajili, G. Scalari, M. Giovannini, M. Beck, M. Rochat, H. Beere, A. G. Davies, E. H. Linfield, and D. Ritchie, Philos. Trans. R. Soc. London 362, 215 (2003).
[CrossRef]

Appl. Phys. Lett. (1)

J. E. Bjarnason, T. L. J. Chan, A. W. M. Lee, M. A. Celis, and E. R. Brown, Appl. Phys. Lett. 85, 519 (2004).
[CrossRef]

IEEE Photonics Technol. Lett. (1)

A. W. M. Lee, B. S. Williams, Q. Hu, and J. L. Reno, IEEE Photonics Technol. Lett. 18, 1415 (2006).
[CrossRef]

Opt. Lett. (1)

Philos. Trans. R. Soc. London (1)

J. Faist, L. Ajili, G. Scalari, M. Giovannini, M. Beck, M. Rochat, H. Beere, A. G. Davies, E. H. Linfield, and D. Ritchie, Philos. Trans. R. Soc. London 362, 215 (2003).
[CrossRef]

Proc. SPIE (3)

B. N. Behnken, M. Lowe, G. Karunasiri, D. Chamberlin, P. R. Robrish, and J. Faist, Proc. SPIE 6549, 65490C (2007).
[CrossRef]

D. A. Zimdars and J. S. White, Proc. SPIE 5411, 78 (2004).
[CrossRef]

J. F. Federici, D. Gary, R. Barat, and D. Zimdars, Proc. SPIE 5781, 75 (2005).
[CrossRef]

Other (5)

K. Humphreys, J. P. Loughran, M. Gradziel, W. Lanigan, T. Ward, J. A. Murphy, and C. O'Sullivan, in Proceedings of the 26th Annual International Conference of the IEEE (IEEE, 2004), pp. 1302-1305.

G. Karunasiri, presented at the 7th International Conference on Technology and the Mine Problem, Monterey, Calif., 2-4 May 2006.

B. N. Behnken, G. Karunasiri, D. Chamberlin, P. R. Robrish, and J. Faist, in Proceedings of the Ninth International Conference on Intersubband Transitions in Quantum Wells, D.Indjin, Z.Ikonic, P.Harrison, and R.W.Kelsall, eds. (University of Leeds, UK, 2007).

R. A. Wood, in Semiconductors and Semimetals, Vol. 47, pp. 43-121 (1997).
[CrossRef]

E. L. Dereniak and S. D. Boreman, Infrared Detectors and Systems (Wiley, 1996).

Supplementary Material (4)

» Media 1: AVI (698 KB)     
» Media 2: AVI (870 KB)     
» Media 3: AVI (783 KB)     
» Media 4: AVI (673 KB)     

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Figures (2)

Fig. 1
Fig. 1

Imaging of a small utility-knife blade wrapped in opaque plastic tape. (a) Conventional digital photograph. Dotted region represents approximate area of illumination. (b) Single-frame image of blade assembly illuminated with 2.8 THz QCL radiation and imaged with microbolometer camera. (c) Image generated by computationally averaging 50 individual frames. (d) Fifty-frame composite image, refined using MATLAB image-processing utility software.

Fig. 2
Fig. 2

(Multimedia online) Single-frame excerpts from video recordings of metallic objects concealed by opaque plastic tape. (a) Utility blade from Fig. 1 (698 KB). (b) Dentist’s pick (870 KB). (c) Paper clip (783 KB). (d) Plastic/wire tie twisted into the shape of a loop (673 KB)

Equations (5)

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NETD = 4 F no 2 A det ϵ π T l ( d L d T ) NEP ,
L ( T ) = ϵ t P ( T ) π ,
P ( T ) 0 v c 2 π k T c 2 v 2 d v 2 π k T 3 c 2 v c 3 ,
NETD = 6 c 2 F no 2 A det ϵ π T l k ϵ t v c 3 NEP .
V J N = [ 4 k B T R Δ f ] 1 2 = 7.0 μ V ,

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