Abstract

The useful compromise between resolution and penetration power of the submillimeter or terahertz (THz) spectral region has long made it attractive for a variety of imaging applications. However, many of the demonstrations of imaging in this spectral region have used strategically oriented targets, especially favorable concealment materials, proximate imaging geometries, etc. This paper reports the results of studies aimed at better understanding the phenomenology of targets, the impact of this phenomenology on various active and passive imaging strategies, and most importantly, the development of imaging strategies that do not require the aforementioned special circumstances. Particular attention is paid to the relationship between active and passive images, especially with respect to how they interact with the illumination- and detector-mode structures of various imaging scenarios. It is concluded that the very large dynamic range that can be obtained with active single-mode systems (including focal-plane arrays) can be used in system designs to overcome the deleterious effects that result from the dominance of specular reflections in single-mode active systems as well as to strategically orient targets to obtain recognition. This will aid in the development of a much more robust and generally useful imaging technology in this spectral region.

© 2008 Optical Society of America

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References

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  1. R. Appleby and H. B. Wallace, “Standoff detection of weapons and contraband in the 100GHz to 1THz region,” IEEE Trans. Antennas Propag. 55, 2944-2956 (2007).
    [Crossref]
  2. R.Appleby and D.A.Wikner, eds., Passive Millimeter-Wave Imaging Technology X, Proc. SPIE 6548 (2007).
  3. D.L.Woolard, R.J.Hwu, M.J.Rosker, and J.O.Jensen, eds., Terahertz for Military and Security Applications IV, Proc. SPIE 6212 (2006).
  4. R.Trebits, J.L.Kurtz, R.Appleby, N.A.Salmon, and D.A.Wikner, eds., Radar Sensor Technology VIII and Passive Millimeter-Wave Imaging Technology VII, Proc. SPIE 5410 (2004).
  5. S. M. Kulpa and E. A. Brown, “Near-millimeter wave technology base study,” HDL-SR-79-8 (Harry Diamond Laboratories, 1979).
  6. G.A.Tanton, ed., Millimeter Optics, Proc. SPIE 259 (1980).
  7. P. W. Kruse, “Why the military interest in near-millimeter wave imaging?” Proc. SPIE 259, 94-97 (1980).
  8. B. B. Hu and M. C. Nuss, “Imaging with terahertz waves,” Opt. Lett. 20, 1716-1718 (1995).
    [Crossref] [PubMed]
  9. K. Wynne and D. A. Jaroszynski, “Superluminal terahertz pulses,” Opt. Lett. 24, 25-27 (1999).
    [Crossref]
  10. Q. Chen, Z. Jiang, G. X. Xu, and X.-C. Zhang, “Near-field terahertz imaging with a dynamic aperture,” Opt. Lett. 25, 1122-1124 (2000).
    [Crossref]
  11. J. O'Hara and D. Grischkowsky, “Quasi-optic synthetic phased-array terahertz imaging,” J. Opt. Soc. Am. B21, 1178-1191 (2004).
  12. D. N. Bittner, R. L. Crownover, F. C. De Lucia, and S. L. Shostak, “Passive imaging with a broadband cooled detector,” 12th International Conference on Infrared and Millimeter Waves (1987).
  13. D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
    [Crossref]
  14. E. N. Grossman, A. Luukanen, and A. J. Miller, “Terahertz active direct detection imagers,” Terahertz for Military and Security Applications II, Proc. SPIE 5411, 68-77 (2004).
    [Crossref]
  15. F. B. Foote, E. E. Reber, and D. T. Hodges, “Active/passive near-millimeter wave imaging for tactical applications,” Millimeter Optics, Proc. SPIE 259, 131-136 (1980).
  16. A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
    [Crossref]
  17. C. C. Aleksoff, “Synthetic-aperture techniques at near-millimeter wavelengths,” Millimeter Optics, Proc. SPIE 259, 115-124 (1980).
  18. N. A. Salmon and R. Appleby, “Sky radiation temperature changes and fluctuations in the millimeter-wave band,” Passive Millimeter-Wave Imaging Technology IV, Proc. SPIE 4032, 98-102 (2000).
    [Crossref]
  19. P. Bhartia and I. J. Bahl, Millimeter Wave Engineering and Applications (Wiley, 1984).
  20. L. Yujiri, M. Shoucri, and P. Moffa, “Passive millimeter-wave imaging,” IEEE Microwave Magazine (2003), pp. 39-50.
    [Crossref]

2007 (1)

R. Appleby and H. B. Wallace, “Standoff detection of weapons and contraband in the 100GHz to 1THz region,” IEEE Trans. Antennas Propag. 55, 2944-2956 (2007).
[Crossref]

2006 (1)

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

2005 (1)

D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
[Crossref]

2004 (2)

E. N. Grossman, A. Luukanen, and A. J. Miller, “Terahertz active direct detection imagers,” Terahertz for Military and Security Applications II, Proc. SPIE 5411, 68-77 (2004).
[Crossref]

J. O'Hara and D. Grischkowsky, “Quasi-optic synthetic phased-array terahertz imaging,” J. Opt. Soc. Am. B21, 1178-1191 (2004).

2003 (1)

L. Yujiri, M. Shoucri, and P. Moffa, “Passive millimeter-wave imaging,” IEEE Microwave Magazine (2003), pp. 39-50.
[Crossref]

2000 (2)

N. A. Salmon and R. Appleby, “Sky radiation temperature changes and fluctuations in the millimeter-wave band,” Passive Millimeter-Wave Imaging Technology IV, Proc. SPIE 4032, 98-102 (2000).
[Crossref]

Q. Chen, Z. Jiang, G. X. Xu, and X.-C. Zhang, “Near-field terahertz imaging with a dynamic aperture,” Opt. Lett. 25, 1122-1124 (2000).
[Crossref]

1999 (1)

1995 (1)

1980 (2)

P. W. Kruse, “Why the military interest in near-millimeter wave imaging?” Proc. SPIE 259, 94-97 (1980).

F. B. Foote, E. E. Reber, and D. T. Hodges, “Active/passive near-millimeter wave imaging for tactical applications,” Millimeter Optics, Proc. SPIE 259, 131-136 (1980).

Aleksoff, C. C.

C. C. Aleksoff, “Synthetic-aperture techniques at near-millimeter wavelengths,” Millimeter Optics, Proc. SPIE 259, 115-124 (1980).

Appleby, R.

R. Appleby and H. B. Wallace, “Standoff detection of weapons and contraband in the 100GHz to 1THz region,” IEEE Trans. Antennas Propag. 55, 2944-2956 (2007).
[Crossref]

N. A. Salmon and R. Appleby, “Sky radiation temperature changes and fluctuations in the millimeter-wave band,” Passive Millimeter-Wave Imaging Technology IV, Proc. SPIE 4032, 98-102 (2000).
[Crossref]

Bahl, I. J.

P. Bhartia and I. J. Bahl, Millimeter Wave Engineering and Applications (Wiley, 1984).

Bandyopadhyay, A.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Barat, R.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Bhartia, P.

P. Bhartia and I. J. Bahl, Millimeter Wave Engineering and Applications (Wiley, 1984).

Bittner, D. N.

D. N. Bittner, R. L. Crownover, F. C. De Lucia, and S. L. Shostak, “Passive imaging with a broadband cooled detector,” 12th International Conference on Infrared and Millimeter Waves (1987).

Brown, E. A.

S. M. Kulpa and E. A. Brown, “Near-millimeter wave technology base study,” HDL-SR-79-8 (Harry Diamond Laboratories, 1979).

Casto, C.

D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
[Crossref]

Chen, Q.

Crownover, R. L.

D. N. Bittner, R. L. Crownover, F. C. De Lucia, and S. L. Shostak, “Passive imaging with a broadband cooled detector,” 12th International Conference on Infrared and Millimeter Waves (1987).

De Lucia, F. C.

D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
[Crossref]

D. N. Bittner, R. L. Crownover, F. C. De Lucia, and S. L. Shostak, “Passive imaging with a broadband cooled detector,” 12th International Conference on Infrared and Millimeter Waves (1987).

Federici, M. D.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Foote, F. B.

F. B. Foote, E. E. Reber, and D. T. Hodges, “Active/passive near-millimeter wave imaging for tactical applications,” Millimeter Optics, Proc. SPIE 259, 131-136 (1980).

Grischkowsky, D.

J. O'Hara and D. Grischkowsky, “Quasi-optic synthetic phased-array terahertz imaging,” J. Opt. Soc. Am. B21, 1178-1191 (2004).

Grossman, E. N.

E. N. Grossman, A. Luukanen, and A. J. Miller, “Terahertz active direct detection imagers,” Terahertz for Military and Security Applications II, Proc. SPIE 5411, 68-77 (2004).
[Crossref]

Helminger, P.

D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
[Crossref]

Hodges, D. T.

F. B. Foote, E. E. Reber, and D. T. Hodges, “Active/passive near-millimeter wave imaging for tactical applications,” Millimeter Optics, Proc. SPIE 259, 131-136 (1980).

Hu, B. B.

Jaroszynski, D. A.

Jiang, Z.

Kruse, P. W.

P. W. Kruse, “Why the military interest in near-millimeter wave imaging?” Proc. SPIE 259, 94-97 (1980).

Kulpa, S. M.

S. M. Kulpa and E. A. Brown, “Near-millimeter wave technology base study,” HDL-SR-79-8 (Harry Diamond Laboratories, 1979).

Luukanen, A.

E. N. Grossman, A. Luukanen, and A. J. Miller, “Terahertz active direct detection imagers,” Terahertz for Military and Security Applications II, Proc. SPIE 5411, 68-77 (2004).
[Crossref]

Michalopoulou, Z.-H.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Miller, A. J.

E. N. Grossman, A. Luukanen, and A. J. Miller, “Terahertz active direct detection imagers,” Terahertz for Military and Security Applications II, Proc. SPIE 5411, 68-77 (2004).
[Crossref]

Moffa, P.

L. Yujiri, M. Shoucri, and P. Moffa, “Passive millimeter-wave imaging,” IEEE Microwave Magazine (2003), pp. 39-50.
[Crossref]

Nuss, M. C.

O'Hara, J.

J. O'Hara and D. Grischkowsky, “Quasi-optic synthetic phased-array terahertz imaging,” J. Opt. Soc. Am. B21, 1178-1191 (2004).

Petkie, D. T.

D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
[Crossref]

Reber, E. E.

F. B. Foote, E. E. Reber, and D. T. Hodges, “Active/passive near-millimeter wave imaging for tactical applications,” Millimeter Optics, Proc. SPIE 259, 131-136 (1980).

Salmon, N. A.

N. A. Salmon and R. Appleby, “Sky radiation temperature changes and fluctuations in the millimeter-wave band,” Passive Millimeter-Wave Imaging Technology IV, Proc. SPIE 4032, 98-102 (2000).
[Crossref]

Schulkin, B.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Sengupta, A.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Shostak, S. L.

D. N. Bittner, R. L. Crownover, F. C. De Lucia, and S. L. Shostak, “Passive imaging with a broadband cooled detector,” 12th International Conference on Infrared and Millimeter Waves (1987).

Shoucri, M.

L. Yujiri, M. Shoucri, and P. Moffa, “Passive millimeter-wave imaging,” IEEE Microwave Magazine (2003), pp. 39-50.
[Crossref]

Stepanov, A.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Wallace, H. B.

R. Appleby and H. B. Wallace, “Standoff detection of weapons and contraband in the 100GHz to 1THz region,” IEEE Trans. Antennas Propag. 55, 2944-2956 (2007).
[Crossref]

Wynne, K.

Xu, G. X.

Yujiri, L.

L. Yujiri, M. Shoucri, and P. Moffa, “Passive millimeter-wave imaging,” IEEE Microwave Magazine (2003), pp. 39-50.
[Crossref]

Zhang, X.-C.

Zimdars, D.

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

IEEE Microwave Magazine (1)

L. Yujiri, M. Shoucri, and P. Moffa, “Passive millimeter-wave imaging,” IEEE Microwave Magazine (2003), pp. 39-50.
[Crossref]

IEEE Trans. Antennas Propag. (1)

R. Appleby and H. B. Wallace, “Standoff detection of weapons and contraband in the 100GHz to 1THz region,” IEEE Trans. Antennas Propag. 55, 2944-2956 (2007).
[Crossref]

J. Opt. Soc. Am. (2)

J. O'Hara and D. Grischkowsky, “Quasi-optic synthetic phased-array terahertz imaging,” J. Opt. Soc. Am. B21, 1178-1191 (2004).

A. Bandyopadhyay, A. Stepanov, B. Schulkin, M. D. Federici, A. Sengupta, R. Barat, Z.-H. Michalopoulou, and D. Zimdars, “Terahertz interferometeric and synthetic aperture imaging,” J. Opt. Soc. Am. A23, 1168-1178 (2006).
[Crossref]

Opt. Lett. (3)

Proc. SPIE (5)

D. T. Petkie, F. C. De Lucia, C. Casto, and P. Helminger, “Active and passive millimeter- and sub-millimeter-wave imaging,” Technologies for Optical Countermeasures II, Femtosecond Phenomena II, and Passive Millimetre-Wave and Terahertz Imaging II, Proc. SPIE 5989, 598918 (2005).
[Crossref]

E. N. Grossman, A. Luukanen, and A. J. Miller, “Terahertz active direct detection imagers,” Terahertz for Military and Security Applications II, Proc. SPIE 5411, 68-77 (2004).
[Crossref]

F. B. Foote, E. E. Reber, and D. T. Hodges, “Active/passive near-millimeter wave imaging for tactical applications,” Millimeter Optics, Proc. SPIE 259, 131-136 (1980).

P. W. Kruse, “Why the military interest in near-millimeter wave imaging?” Proc. SPIE 259, 94-97 (1980).

N. A. Salmon and R. Appleby, “Sky radiation temperature changes and fluctuations in the millimeter-wave band,” Passive Millimeter-Wave Imaging Technology IV, Proc. SPIE 4032, 98-102 (2000).
[Crossref]

Other (8)

P. Bhartia and I. J. Bahl, Millimeter Wave Engineering and Applications (Wiley, 1984).

C. C. Aleksoff, “Synthetic-aperture techniques at near-millimeter wavelengths,” Millimeter Optics, Proc. SPIE 259, 115-124 (1980).

D. N. Bittner, R. L. Crownover, F. C. De Lucia, and S. L. Shostak, “Passive imaging with a broadband cooled detector,” 12th International Conference on Infrared and Millimeter Waves (1987).

R.Appleby and D.A.Wikner, eds., Passive Millimeter-Wave Imaging Technology X, Proc. SPIE 6548 (2007).

D.L.Woolard, R.J.Hwu, M.J.Rosker, and J.O.Jensen, eds., Terahertz for Military and Security Applications IV, Proc. SPIE 6212 (2006).

R.Trebits, J.L.Kurtz, R.Appleby, N.A.Salmon, and D.A.Wikner, eds., Radar Sensor Technology VIII and Passive Millimeter-Wave Imaging Technology VII, Proc. SPIE 5410 (2004).

S. M. Kulpa and E. A. Brown, “Near-millimeter wave technology base study,” HDL-SR-79-8 (Harry Diamond Laboratories, 1979).

G.A.Tanton, ed., Millimeter Optics, Proc. SPIE 259 (1980).

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Figures (12)

Fig. 1
Fig. 1

Block diagram of the 640 GHz active imaging system.

Fig. 2
Fig. 2

Passive image (upper) and active image (lower). Both are at λ 0.5 mm ( 600 GHz ) and have similar, diffraction-limited spot sizes of 5 mm on the target image. However, the upper image is of a clean-shaven individual with a mustache, whereas the lower image is of a bald individual with a full beard.

Fig. 3
Fig. 3

Signal intensity taken along the horizontal line in the active image of Fig. 2.

Fig. 4
Fig. 4

Histogram alteration of active image (gamma correction and stretching).

Fig. 5
Fig. 5

94 GHz radiometer image taken outdoors with cold sky illumination (courtesy of R. Appleby).

Fig. 6
Fig. 6

640 GHz passive image of a gun in front of a warm background (right) and an image of the same gun illuminated by a cold illuminator that fills 15 ° (left).

Fig. 7
Fig. 7

640 GHz active image of a mirror at normal incidence. The left and right sides of the mirror are covered by Eccosorb, and the top half is covered by a thin scarf. Below the image is a quantitative plot of the averaged signal intensities between the two horizontal lines in the image. The image was recorded and displayed on a logarithmic scale because of its large dynamic range. The T-shaped object in the lower half of the image is a support structure.

Fig. 8
Fig. 8

640 GHz active image of the same system as shown in Fig. 7, but at an incidence angle of 10 ° to the normal. Below the image is a quantitative plot (solid curve) of the signal intensities between the solid lines in the images. Below the image is a quantitative plot (dotted curve) of the signal intensities between the dotted lines in the images.

Fig. 9
Fig. 9

Active image of a toy gun recorded and displayed on a logarithmic scale (upper). The quantitative reflection (relative to a normal specular reflection) along the horizontal line is shown in the lower panel.

Fig. 10
Fig. 10

Active image displayed on a linear scale of the same object displayed on a log scale in Fig. 9.

Fig. 11
Fig. 11

Logarithmic images of the toy gun rotated 10°, 20°, and 40° relative to the normal (left to right in the upper panels). Logarithmic intensities along the horizontal line in the upper panels of the toy gun rotated 10°, 20°, and 40° relative to the normal specular reflection (left to right in the lower panels).

Fig. 12
Fig. 12

Active image of a 4.25 cm diameter metallic cylinder with end caps recorded and displayed on a logarithmic scale (upper). The average reflected signal between the horizontal lines in the figure is also shown (lower).

Equations (9)

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

T I = P I k Δ ν .
P N = k T N ( B b ) 1 2 ,
P I = k T I b ,
S N = ( T I T N ) ( b B ) 1 2 ) ,
T I = T N ( B b ) 1 2 .
T I = ( P I k Δ ν ) ( λ s s ) 2 = ( P I k Δ ν ) ( D r ) 2 ,
T I ( P I k Δ ν ) ( λ l ) 2 .
Ω b l a c k b o d y mode = λ 2 A .
T I R ( P I k Δ ν ) ( λ l ) 2 .

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