Abstract

We investigate two approaches to improving the resolution of time-reversal based THz imaging systems. First, we show that a substantial improvement in the reconstruction of time-reversed THz fields is achieved by increasing the system’s numerical aperture via a waveguide technique adapted from ultrasound imaging. Second, a model-based reconstruction algorithm is developed as an alternative to time-reversal THz imaging and its performance is demonstrated for cases with and without a waveguide.

© 2009 OSA

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  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(6), 1085–1094 (1999).
    [CrossRef]
  2. A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
    [CrossRef]
  3. T. Buma and T. B. Norris, “Time reversal three-dimensional imaging using single-cycle terahertz pulses,” Appl. Phys. Lett. 84(12), 2196–2198 (2004).
    [CrossRef]
  4. P. Roux, B. Roman, and M. Fink, “Time-reversal in an ultrasonic waveguide,” Appl. Phys. Lett. 70(14), 1811–1813 (1997).
    [CrossRef]
  5. J. A. Fessler, “Penalized weighted least-squares image reconstruction for positron emission tomography,” IEEE Trans. Med. Imaging 13(2), 290–300 (1994).
    [CrossRef] [PubMed]
  6. Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
    [CrossRef]
  7. Z. Jiang and X.-C. Zhang, “2D measurement and spatio-temporal coupling of few-cycle THz pulses,” Opt. Express 5(11), 243–248 (1999).
    [CrossRef] [PubMed]

2004

T. Buma and T. B. Norris, “Time reversal three-dimensional imaging using single-cycle terahertz pulses,” Appl. Phys. Lett. 84(12), 2196–2198 (2004).
[CrossRef]

2002

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

1999

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(6), 1085–1094 (1999).
[CrossRef]

Z. Jiang and X.-C. Zhang, “2D measurement and spatio-temporal coupling of few-cycle THz pulses,” Opt. Express 5(11), 243–248 (1999).
[CrossRef] [PubMed]

1998

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

1997

P. Roux, B. Roman, and M. Fink, “Time-reversal in an ultrasonic waveguide,” Appl. Phys. Lett. 70(14), 1811–1813 (1997).
[CrossRef]

1994

J. A. Fessler, “Penalized weighted least-squares image reconstruction for positron emission tomography,” IEEE Trans. Med. Imaging 13(2), 290–300 (1994).
[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(6), 1085–1094 (1999).
[CrossRef]

Brener, I.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Buma, T.

T. Buma and T. B. Norris, “Time reversal three-dimensional imaging using single-cycle terahertz pulses,” Appl. Phys. Lett. 84(12), 2196–2198 (2004).
[CrossRef]

Cai, Y.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Decker, J.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Federici, J. F.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Fessler, J. A.

J. A. Fessler, “Penalized weighted least-squares image reconstruction for positron emission tomography,” IEEE Trans. Med. Imaging 13(2), 290–300 (1994).
[CrossRef] [PubMed]

Fink, M.

P. Roux, B. Roman, and M. Fink, “Time-reversal in an ultrasonic waveguide,” Appl. Phys. Lett. 70(14), 1811–1813 (1997).
[CrossRef]

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(6), 1085–1094 (1999).
[CrossRef]

Jiang, Z.

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(6), 1085–1094 (1999).
[CrossRef]

Le Hors, L.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Lopata, J.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[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(6), 1085–1094 (1999).
[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(6), 1085–1094 (1999).
[CrossRef]

Norris, T. B.

T. Buma and T. B. Norris, “Time reversal three-dimensional imaging using single-cycle terahertz pulses,” Appl. Phys. Lett. 84(12), 2196–2198 (2004).
[CrossRef]

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Pfeiffer, L.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Roman, B.

P. Roux, B. Roman, and M. Fink, “Time-reversal in an ultrasonic waveguide,” Appl. Phys. Lett. 70(14), 1811–1813 (1997).
[CrossRef]

Roux, P.

P. Roux, B. Roman, and M. Fink, “Time-reversal in an ultrasonic waveguide,” Appl. Phys. Lett. 70(14), 1811–1813 (1997).
[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(6), 1085–1094 (1999).
[CrossRef]

Ruffin, A. B.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Sanchez-Palencia, L.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Stark, J. B.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Van Rudd, J.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Whitaker, J. F.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

Wu, Q.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Wynn, J.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Zhang, X. C.

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

Zhang, X.-C.

Appl. Phys. B

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(6), 1085–1094 (1999).
[CrossRef]

Appl. Phys. Lett.

T. Buma and T. B. Norris, “Time reversal three-dimensional imaging using single-cycle terahertz pulses,” Appl. Phys. Lett. 84(12), 2196–2198 (2004).
[CrossRef]

P. Roux, B. Roman, and M. Fink, “Time-reversal in an ultrasonic waveguide,” Appl. Phys. Lett. 70(14), 1811–1813 (1997).
[CrossRef]

Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, “Coherent terahertz radiation detection: Direct comparison between free-space electro-optic sampling and antenna detection,” Appl. Phys. Lett. 73(4), 444–446 (1998).
[CrossRef]

IEEE J. Quantum Electron.

A. B. Ruffin, J. Van Rudd, J. Decker, L. Sanchez-Palencia, L. Le Hors, J. F. Whitaker, and T. B. Norris, “Time Reversal Terahertz Imaging,” IEEE J. Quantum Electron. 38(8), 1110–1119 (2002).
[CrossRef]

IEEE Trans. Med. Imaging

J. A. Fessler, “Penalized weighted least-squares image reconstruction for positron emission tomography,” IEEE Trans. Med. Imaging 13(2), 290–300 (1994).
[CrossRef] [PubMed]

Opt. Express

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Figures (5)

Fig. 1.
Fig. 1.

Experimental setup

Fig. 2.
Fig. 2.

Measured THz wavefield plots without a waveguide and with a symmetric and asymmetric placed waveguide and the corresponding reconstructed images based on time-reversal.

Fig. 3.
Fig. 3.

Intensity plots for symmetric (a) and asymmetric (c) waveguide configurations. Resolution plots for symmetric (b) and asymmetric (d) waveguide configurations.

Fig. 4.
Fig. 4.

Absolute (a) and normalized intensity (b) obtained by the RLS algorithm (red curve) versus the time-reversal algorithm (blue curve). Figure 4(c) & (d) show the similarity of the measured and simulated fields. Figure 4(e) shows the measured and forward-propagated RLS-reconstructed THz waveform.

Fig. 5.
Fig. 5.

Absolute (a) and normalized intensity (b) obtained by the RLS algorithm (red curve) versus time-reversal with waveguide (blue curve). Both plots show the peak intensity relative to the time-reversal algorithm without the waveguide. Figure 5(c) & (d) show the slight discrepancy between the measured and simulated wavefield data. Figure 5(e) shows the measured and simulated THz signals at detector position 10.

Equations (5)

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

Sm(t)=Σn=1Nh(tτnm)θn
[S1(t)S2(t)Sm(t)]=[h(tτ11)h(tτ12)h(tτ1n)h(tτ21)h(tτ22)h(tτ2n)h(tτm1)h(tτm2)h(tτmn)][θ1θ2θn]
Y=AΘ
θ̂=argminθYAθ2
θ̂=argminθYAθ2+βΣn=2N(θnθn1)2

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