Abstract

We present a high-resolution terahertz (THz) reflective imaging system, operating at 2.52THz, that employs a continuous-wave THz gas laser and a pyroelectric detector. The spatial resolution was evaluated from the system’s modulation transfer function and tested by scanning a series of resolution targets. To further improve the image quality, Lucy–Richardson method was adopted to restore the scanning result. With the scanning spot profile measured using knife edge method, a satisfying restoration result can be obtained. Finally, the system’s performance was observed by imaging some different test objects.

© 2010 Optical Society of America

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    [CrossRef]

2010

2009

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

N. N. Zinov’ev and A. V. Andrianov, “Confocal terahertz imaging,” Appl. Phys. Lett. 95, 011114 (2009).
[CrossRef]

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

S. Huang, P. C. Ashworth, K. W. C. Kan, Y. Chen, V. P. Wallace, Y.-T. Zhang, and E. Pickwell-MacPherson, “Improved sample characterization in terahertz reflection imaging and spectroscopy,” Opt. Express 17, 3848–3854 (2009).
[CrossRef] [PubMed]

2008

2007

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

2006

E. Pickwell and V. P. Wallace, “Biomedical applications of terahertz technology,” J. Phys. D 39, R301–R310 (2006).
[CrossRef]

2005

R. M. Woodward, “Terahertz technology in global homeland security,” Proc. SPIE 5781, 22–31 (2005).
[CrossRef]

1997

1995

Abraham, E.

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Alcin, A.

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

am Weg, C.

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

Andrews, M.

Andrianov, A. V.

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

N. N. Zinov’ev and A. V. Andrianov, “Confocal terahertz imaging,” Appl. Phys. Lett. 95, 011114 (2009).
[CrossRef]

Ashworth, P. C.

Biggs, D. S. C.

Bjarnason, J. E.

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

Brown, E. R.

Z. D. Taylor, R. S. Singh, M. O. Culjat, J. Y. Suen, W. S. Grundfest, H. Lee, and E. R. Brown, “Reflective terahertz imaging of porcine skin burns,” Opt. Lett. 33, 1258–1260 (2008).
[CrossRef] [PubMed]

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

Chakraborty, S.

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Chamberlain, J. M.

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

Chen, Y.

Culjat, M. O.

Davies, A. G.

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Dean, P.

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Delagnes, J. C

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Ding, S.

Q. Li, Q. Yin, R. Yao, S. Ding, and Q. Wang, “Continuous-wave terahertz scanning image resolution analysis and restoration,” Opt. Eng. 49, 037007 (2010).
[CrossRef]

El Fatimy, A.

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Gallant, A. J.

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

Giehler, M.

Gossard, A. C.

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

Grahn, H. T.

Greiner-Bär, M.

Grundfest, W. S.

Guo, Y. J.

Y. Li, L. Li, A. Hellicar, and Y. J. Guo, “Super-resolution reconstruction of terahertz images,” Proc. SPIE 6949, 69490J(2008).
[CrossRef]

Hanson, M. P.

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

Hellicar, A.

Y. Li, L. Li, A. Hellicar, and Y. J. Guo, “Super-resolution reconstruction of terahertz images,” Proc. SPIE 6949, 69490J(2008).
[CrossRef]

Hey, R.

Hils, B.

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

Hochrein, T.

Hu, B. B.

Huang, S.

Hübers, H.-W.

Jansen, C.

Jördens, C.

Kan, K. W. C.

Khanna, S.

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Koch, M.

Krumbholz, N.

Lachab, M.

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Lee, H.

Li, L.

Y. Li, L. Li, A. Hellicar, and Y. J. Guo, “Super-resolution reconstruction of terahertz images,” Proc. SPIE 6949, 69490J(2008).
[CrossRef]

Li, Q.

Q. Li, Q. Yin, R. Yao, S. Ding, and Q. Wang, “Continuous-wave terahertz scanning image resolution analysis and restoration,” Opt. Eng. 49, 037007 (2010).
[CrossRef]

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Li, Y.

Y. Li, L. Li, A. Hellicar, and Y. J. Guo, “Super-resolution reconstruction of terahertz images,” Proc. SPIE 6949, 69490J(2008).
[CrossRef]

Linfield, E. H.

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Liu, M.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Liu, X.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Löffler, T.

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

MacPherson, E.

May, T.

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

Mounaix, P.

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Nguéma, E.

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Nuss, M. C.

Pavlov, S. G.

Peters, O.

Pickwell, E.

E. Pickwell and V. P. Wallace, “Biomedical applications of terahertz technology,” J. Phys. D 39, R301–R310 (2006).
[CrossRef]

Pickwell-MacPherson, E.

Pupeza, I.

M. A. Salhi, I. Pupeza, and M. Koch, “Confocal THz laser microscope,” J. Infrared Milli. Terahz. Waves 31, 358–366 (2010).

Reid, C.

Richter, H.

Roskos, H. G.

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

Salhi, M.

Salhi, M. A.

M. A. Salhi, I. Pupeza, and M. Koch, “Confocal THz laser microscope,” J. Infrared Milli. Terahz. Waves 31, 358–366 (2010).

Scheller, M.

Schrottke, L.

Semenov, A. D.

Shan, J.

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Singh, R. S.

Z. D. Taylor, R. S. Singh, M. O. Culjat, J. Y. Suen, W. S. Grundfest, H. Lee, and E. R. Brown, “Reflective terahertz imaging of porcine skin burns,” Opt. Lett. 33, 1258–1260 (2008).
[CrossRef] [PubMed]

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

Song, Q.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Suen, J. Y.

Taylor, Z. D.

Z. D. Taylor, R. S. Singh, M. O. Culjat, J. Y. Suen, W. S. Grundfest, H. Lee, and E. R. Brown, “Reflective terahertz imaging of porcine skin burns,” Opt. Lett. 33, 1258–1260 (2008).
[CrossRef] [PubMed]

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

Trukhin, V. N.

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

Vieweg, N.

Wallace, H. B.

Wallace, V. P.

Wang, Q.

Q. Li, Q. Yin, R. Yao, S. Ding, and Q. Wang, “Continuous-wave terahertz scanning image resolution analysis and restoration,” Opt. Eng. 49, 037007 (2010).
[CrossRef]

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Wienold, M.

Wietzke, S.

Woodward, R. M.

R. M. Woodward, “Terahertz technology in global homeland security,” Proc. SPIE 5781, 22–31 (2005).
[CrossRef]

Yao, R.

Q. Li, Q. Yin, R. Yao, S. Ding, and Q. Wang, “Continuous-wave terahertz scanning image resolution analysis and restoration,” Opt. Eng. 49, 037007 (2010).
[CrossRef]

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Yin, Q.

Q. Li, Q. Yin, R. Yao, S. Ding, and Q. Wang, “Continuous-wave terahertz scanning image resolution analysis and restoration,” Opt. Eng. 49, 037007 (2010).
[CrossRef]

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Younus, A.

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Yu, F.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Yu, Q.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Zeitler, J. A.

Zhang, C.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Zhang, Y.-T.

Zhao, Y.

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

Zinov’ev, N. N.

N. N. Zinov’ev and A. V. Andrianov, “Confocal terahertz imaging,” Appl. Phys. Lett. 95, 011114 (2009).
[CrossRef]

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

Appl. Opt.

Appl. Phys. Lett.

N. N. Zinov’ev and A. V. Andrianov, “Confocal terahertz imaging,” Appl. Phys. Lett. 95, 011114 (2009).
[CrossRef]

T. Löffler, T. May, C. am Weg, A. Alcin, B. Hils, and H. G. Roskos, “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
[CrossRef]

J. Infrared Milli. Terahz. Waves

M. A. Salhi, I. Pupeza, and M. Koch, “Confocal THz laser microscope,” J. Infrared Milli. Terahz. Waves 31, 358–366 (2010).

J. Opt. Soc. Am. A

J. Phys. D

E. Pickwell and V. P. Wallace, “Biomedical applications of terahertz technology,” J. Phys. D 39, R301–R310 (2006).
[CrossRef]

JETP Lett.

N. N. Zinov’ev, A. V. Andrianov, A. J. Gallant, J. M. Chamberlain, and V. N. Trukhin, “Contrast and resolution enhancement in a confocal terahertz video system,” JETP Lett. 88, 492–495(2009).
[CrossRef]

Opt. Commun.

E. Abraham, A. Younus, A. El Fatimy, J. C Delagnes, E. Nguéma, and P. Mounaix, “Broadband terahertz imaging of documents written with lead pencils,” Opt. Commun. 282, 3104–3107(2009).
[CrossRef]

Opt. Eng.

Q. Li, Q. Yin, R. Yao, S. Ding, and Q. Wang, “Continuous-wave terahertz scanning image resolution analysis and restoration,” Opt. Eng. 49, 037007 (2010).
[CrossRef]

Opt. Express

Opt. Lett.

Proc. SPIE

P. Dean, S. Khanna, S. Chakraborty, M. Lachab, A. G. Davies, and E. H. Linfield, “Diffuse reflection imaging at terahertz frequencies for security applications,” Proc. SPIE 6741, 67410R (2007).
[CrossRef]

Q. Li, R. Yao, Q. Yin, J. Shan, and Q. Wang, “2.52THz scanning reflection imaging and image preprocessing,” Proc. SPIE 7277, 72770J (2009).

Q. Song, F. Yu, Y. Zhao, C. Zhang, Q. Yu, M. Liu, and X. Liu, “The restoration of CW THz images based on phase analysis,” Proc. SPIE 7443, 74432G (2009).
[CrossRef]

R. M. Woodward, “Terahertz technology in global homeland security,” Proc. SPIE 5781, 22–31 (2005).
[CrossRef]

Y. Li, L. Li, A. Hellicar, and Y. J. Guo, “Super-resolution reconstruction of terahertz images,” Proc. SPIE 6949, 69490J(2008).
[CrossRef]

Other

Z. D. Taylor, R. S. Singh, E. R. Brown, J. E. Bjarnason, M. P. Hanson, and A. C. Gossard, “A reflection based, pulsed THz imaging system with 1mm spatial resolution,” in Microwave Symposium, 2007. IEEE/MTT-S International (IEEE, 2007), pp. 1161–1164.
[CrossRef]

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Figures (8)

Fig. 1
Fig. 1

Experimental setup for THz reflective imaging.

Fig. 2
Fig. 2

Measurement result of the knife edge method. Inset, calculated MTF.

Fig. 3
Fig. 3

Scanning result of a razor blade: (a) scanning result of former imaging system, (b) scanning result of current imaging system, (c) scanning result when the target was covered by one piece of paper.

Fig. 4
Fig. 4

Scanning results of 0.4 mm thick strips: (a) vertical strips, (b) horizontal strips.

Fig. 5
Fig. 5

Image restoration results of 0.4 mm thick strips: (a) vertical strips, (b) horizontal strips.

Fig. 6
Fig. 6

Scanning result of a Chinese character “Dragon”: (a) scanning result, (b) image restoration.

Fig. 7
Fig. 7

Scanning result of a metal sheet: (a) photo of the sample, where the word is “BeLLE”, (b) scanning result, (c) image restoration.

Fig. 8
Fig. 8

Scanning result of a coin: (a) photo of the sample, (b) scanning result, (c) after fluctuation suppression, (d) image restoration.

Equations (3)

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I ( x ) = I 0 [ 1 + erf ( 2 ln 2 x x c d ) ] ,
f ^ k + 1 ( x , y ) = f ^ k ( x , y ) [ h ( x , y ) * g ( x , y ) h ( x , y ) * f ^ k ( x , y ) ] ,
h ( x , y ) = { k exp [ 2 ( x x 0 ) ω x 2 Δ x 2 2 ( y y 0 ) 2 ω y 2 Δ y 2 ] , ( x , y ) C 0 , others ,

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