Abstract

We demonstrate terahertz (THz) imaging with a quasi-time-domain spectrometer. This type of THz system is inexpensive, compact, and relatively easy to set up. Beating the simultaneously emitted equidistant modes of a compact diode laser allows for analysis of samples at multiple frequencies with a single measurement. Thus, this technique merges the potential of terahertz time-domain spectrometers with the simplicity of continuous wave lasers. Multiple imaging applications and stability issues are discussed.

© 2011 Optical Society of America

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2010 (4)

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

M. Scheller, K. Baaske, and M. Koch, “Multifrequency continuous wave terahertz spectroscopy for absolute thickness determination,” Appl. Phys. Lett. 96, 151112 (2010).
[CrossRef]

C. Brenner, M. Hofmann, M. Scheller, M. K. Shakfa, M. Koch, I. C. Mayorga, A. Klehr, G. Erbert, and G. Tränkle, “Compact diode-laser-based system for continuous-wave and quasi-time-domain terahertz spectroscopy,” Opt. Lett. 35, 3859–3861(2010).
[CrossRef] [PubMed]

X. Wang, L. Hou, and Y. Zhang, “Continuous-wave terahertz interferometry with multiwavelength phase unwrapping,” Appl. Opt. 49, 5095–5102 (2010).
[CrossRef] [PubMed]

2009 (6)

C. Jördens, M. Scheller, M. Wichmann, M. Mikulics, K. Wiesauer, and M. Koch, “Terahertz birefringence for orientation analysis,” Appl. Opt. 48, 2037–2044 (2009).
[CrossRef] [PubMed]

M. Scheller and M. Koch, “Fast and accurate thickness determination of unknown materials using terahertz time domain spectroscopy,” J. Infrared Millimeter Terahertz Waves 30, 762–769 (2009).
[CrossRef]

M. Scheller, C. Jansen, and M. Koch, “Analyzing sub-100 Μm samples with transmission terahertz time domain spectroscopy,” Opt. Commun. 282, 1304–1306 (2009).
[CrossRef]

M. Scheller and M. Koch, “Terahertz quasi-time domain spectroscopy,” Opt. Express 17, 17723–17733 (2009).
[CrossRef] [PubMed]

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

2008 (4)

2006 (1)

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

2005 (2)

2004 (1)

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

2002 (1)

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

2001 (1)

1999 (1)

1998 (1)

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

1997 (1)

S. Matsuura, M. Tani, and K. Sakai, “Generation of coherent terahertz radiation by photomixing in dipole photoconductive antennas,” Appl. Phys. Lett. 70, 559–561 (1997).
[CrossRef]

1985 (1)

Araki, T.

Auston, D. H.

Baaske, K.

M. Scheller, K. Baaske, and M. Koch, “Multifrequency continuous wave terahertz spectroscopy for absolute thickness determination,” Appl. Phys. Lett. 96, 151112 (2010).
[CrossRef]

Baraniuk, R. G.

Bastian, M.

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

Bauer, T.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Bitzer, A.

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Blackshire, J. L.

Bohn, M. J.

Böttcher, J.

Breitenstein, B.

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

Brenner, C.

Calawa, S.

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

Chen, Y.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Cheung, K. P.

Coutaz, J.

Czasch, S.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Dai, J.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Dinatale, W. F.

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

Dorney, T. D.

Duerr, E. K.

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

Duvillaret, L.

Erbert, G.

Ewert, U.

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

Ezdi, K.

Fischer, B. M.

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Fletcher, C.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Garet, F.

Hangyo, M.

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

Hasek, T.

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

Helm, H.

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Hochrein, T.

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

Hofmann, M.

Hou, L.

Hübers, H. W.

Isu, T.

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

Jansen, C.

M. Scheller, C. Jansen, and M. Koch, “Analyzing sub-100 Μm samples with transmission terahertz time domain spectroscopy,” Opt. Commun. 282, 1304–1306 (2009).
[CrossRef]

Johnson, K.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Jördens, C.

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

C. Jördens, M. Scheller, M. Wichmann, M. Mikulics, K. Wiesauer, and M. Koch, “Terahertz birefringence for orientation analysis,” Appl. Opt. 48, 2037–2044 (2009).
[CrossRef] [PubMed]

Karpowicz, N.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Klehr, A.

Koch, M.

M. Scheller, K. Baaske, and M. Koch, “Multifrequency continuous wave terahertz spectroscopy for absolute thickness determination,” Appl. Phys. Lett. 96, 151112 (2010).
[CrossRef]

C. Brenner, M. Hofmann, M. Scheller, M. K. Shakfa, M. Koch, I. C. Mayorga, A. Klehr, G. Erbert, and G. Tränkle, “Compact diode-laser-based system for continuous-wave and quasi-time-domain terahertz spectroscopy,” Opt. Lett. 35, 3859–3861(2010).
[CrossRef] [PubMed]

M. Scheller and M. Koch, “Terahertz quasi-time domain spectroscopy,” Opt. Express 17, 17723–17733 (2009).
[CrossRef] [PubMed]

M. Scheller, C. Jansen, and M. Koch, “Analyzing sub-100 Μm samples with transmission terahertz time domain spectroscopy,” Opt. Commun. 282, 1304–1306 (2009).
[CrossRef]

M. Scheller and M. Koch, “Fast and accurate thickness determination of unknown materials using terahertz time domain spectroscopy,” J. Infrared Millimeter Terahertz Waves 30, 762–769 (2009).
[CrossRef]

C. Jördens, M. Scheller, M. Wichmann, M. Mikulics, K. Wiesauer, and M. Koch, “Terahertz birefringence for orientation analysis,” Appl. Opt. 48, 2037–2044 (2009).
[CrossRef] [PubMed]

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, “Impact of the contact metallization on the performance of photoconductive THz antennas,” Opt. Express 16, 19695–19705 (2008).
[CrossRef] [PubMed]

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

Kretschmer, K.

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

Krumbholz, N.

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

Künzel, H.

Leonhardt, R.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Lesimple, A.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Löffler, T.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Lu, X.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Mamer, O.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Matsuura, S.

S. Matsuura, M. Tani, and K. Sakai, “Generation of coherent terahertz radiation by photomixing in dipole photoconductive antennas,” Appl. Phys. Lett. 70, 559–561 (1997).
[CrossRef]

Mayorga, I. C.

McIntosh, K. A.

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

Mikulics, M.

Mittleman, D. M.

Molvar, K. A.

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

Ortner, A.

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Planken, P. C. M.

Price-Gallagher, M.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Quast, H.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Richter, H.

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

Roehle, H.

Roskos, H. G.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Rutz, F.

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

Sakai, K.

S. Matsuura, M. Tani, and K. Sakai, “Generation of coherent terahertz radiation by photomixing in dipole photoconductive antennas,” Appl. Phys. Lett. 70, 559–561 (1997).
[CrossRef]

Sartorius, B.

Sawanaka, K.

Schell, M.

Scheller, M.

M. Scheller, K. Baaske, and M. Koch, “Multifrequency continuous wave terahertz spectroscopy for absolute thickness determination,” Appl. Phys. Lett. 96, 151112 (2010).
[CrossRef]

C. Brenner, M. Hofmann, M. Scheller, M. K. Shakfa, M. Koch, I. C. Mayorga, A. Klehr, G. Erbert, and G. Tränkle, “Compact diode-laser-based system for continuous-wave and quasi-time-domain terahertz spectroscopy,” Opt. Lett. 35, 3859–3861(2010).
[CrossRef] [PubMed]

M. Scheller and M. Koch, “Terahertz quasi-time domain spectroscopy,” Opt. Express 17, 17723–17733 (2009).
[CrossRef] [PubMed]

M. Scheller and M. Koch, “Fast and accurate thickness determination of unknown materials using terahertz time domain spectroscopy,” J. Infrared Millimeter Terahertz Waves 30, 762–769 (2009).
[CrossRef]

M. Scheller, C. Jansen, and M. Koch, “Analyzing sub-100 Μm samples with transmission terahertz time domain spectroscopy,” Opt. Commun. 282, 1304–1306 (2009).
[CrossRef]

C. Jördens, M. Scheller, M. Wichmann, M. Mikulics, K. Wiesauer, and M. Koch, “Terahertz birefringence for orientation analysis,” Appl. Opt. 48, 2037–2044 (2009).
[CrossRef] [PubMed]

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, “Impact of the contact metallization on the performance of photoconductive THz antennas,” Opt. Express 16, 19695–19705 (2008).
[CrossRef] [PubMed]

Schlak, M.

Selmar, D.

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

Shakfa, M. K.

Siebert, K. J.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Stanze, D.

Stoik, C. D.

Tani, M.

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

S. Matsuura, M. Tani, and K. Sakai, “Generation of coherent terahertz radiation by photomixing in dipole photoconductive antennas,” Appl. Phys. Lett. 70, 559–561 (1997).
[CrossRef]

Teramura, S.

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

Thoman, A.

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Thomson, M.

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

Tomita, N.

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

Tränkle, G.

van der Marel, W. A. M.

van der Valk, N. C. J.

Venghaus, H.

Verghese, S.

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

Vieweg, N.

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

N. Vieweg, M. Mikulics, M. Scheller, K. Ezdi, R. Wilk, H. W. Hübers, and M. Koch, “Impact of the contact metallization on the performance of photoconductive THz antennas,” Opt. Express 16, 19695–19705 (2008).
[CrossRef] [PubMed]

Walther, M.

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Wang, X.

Wichmann, M.

Wiesauer, K.

Wilk, R.

Yamaguchi, M.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

Yamamoto, K.

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

Yasuda, T.

Yasui, T.

Zhang, C.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Zhang, L.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Zhang, X.-C.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Zhang, Y.

Zhao, H.

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

Anal. Bioanal. Chem. (1)

M. Walther, B. M. Fischer, A. Ortner, A. Bitzer, A. Thoman, and H. Helm, “Chemical sensing and imaging with pulsed terahertz radiation,” Anal. Bioanal. Chem. 397, 1009–1017(2010).
[CrossRef] [PubMed]

Appl. Opt. (4)

Appl. Phys. Lett. (7)

F. Rutz, T. Hasek, M. Koch, H. Richter, and U. Ewert, “Terahertz birefringence of liquid crystal polymers,” Appl. Phys. Lett. 89, 221911 (2006).
[CrossRef]

S. Matsuura, M. Tani, and K. Sakai, “Generation of coherent terahertz radiation by photomixing in dipole photoconductive antennas,” Appl. Phys. Lett. 70, 559–561 (1997).
[CrossRef]

S. Verghese, K. A. McIntosh, S. Calawa, W. F. Dinatale, E. K. Duerr, and K. A. Molvar, “Generation and detection of coherent terahertz waves using two photomixers,” Appl. Phys. Lett. 73, 3824–3826 (1998).
[CrossRef]

K. J. Siebert, H. Quast, R. Leonhardt, T. Löffler, M. Thomson, T. Bauer, H. G. Roskos, and S. Czasch, “Continuous-wave all-optoelectronic terahertz imaging,” Appl. Phys. Lett. 80, 3003–3005 (2002).
[CrossRef]

M. Scheller, K. Baaske, and M. Koch, “Multifrequency continuous wave terahertz spectroscopy for absolute thickness determination,” Appl. Phys. Lett. 96, 151112 (2010).
[CrossRef]

N. Karpowicz, J. Dai, X. Lu, Y. Chen, M. Yamaguchi, H. Zhao, X.-C. Zhang, L. Zhang, C. Zhang, M. Price-Gallagher, C. Fletcher, O. Mamer, A. Lesimple, and K. Johnson, “Coherent heterodyne time-domain spectrometry covering the entire terahertz gap,” Appl. Phys. Lett. 92, 011131 (2008).
[CrossRef]

K. Yamamoto, M. Yamaguchi, M. Tani, M. Hangyo, S. Teramura, T. Isu, and N. Tomita, “Degradation diagnosis of ultrahigh-molecular weight polyethylene with terahertz-time-domain spectroscopy,” Appl. Phys. Lett. 85, 5194–5196(2004).
[CrossRef]

J. Biol. Phys. (1)

C. Jördens, M. Scheller, B. Breitenstein, D. Selmar, and M. Koch, “Evaluation of the leaf water status by means of the permittivity at terahertz frequencies,” J. Biol. Phys. 35, 255–264 (2009).
[CrossRef] [PubMed]

J. Infrared Millimeter Terahertz Waves (1)

M. Scheller and M. Koch, “Fast and accurate thickness determination of unknown materials using terahertz time domain spectroscopy,” J. Infrared Millimeter Terahertz Waves 30, 762–769 (2009).
[CrossRef]

J. Opt. Soc. Am. A (1)

J. Opt. Soc. Am. B (1)

Opt. Commun. (1)

M. Scheller, C. Jansen, and M. Koch, “Analyzing sub-100 Μm samples with transmission terahertz time domain spectroscopy,” Opt. Commun. 282, 1304–1306 (2009).
[CrossRef]

Opt. Express (4)

Opt. Lett. (2)

Polymer Testing (1)

N. Krumbholz, T. Hochrein, N. Vieweg, T. Hasek, K. Kretschmer, M. Bastian, M. Mikulics, and M. Koch, “Monitoring polymeric compounding processes inline with THz time-domain spectroscopy,” Polymer Testing 28, 30–35 (2009).
[CrossRef]

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Figures (8)

Fig. 1
Fig. 1

Scheme of the QTDS system. The emission of a laser module is divided by a beam splitter into two parts. One fraction of the light is directed to the emitter antenna by mirror M1. The other fraction is guided over a delay stage and then focuses onto the detector by mirrors M2 and M3. Four parabolic mirrors (P1 to P4) collimate and focus the THz waves. The samples were mea sured at the position of the THz focus and translated in a two- dimensional plane ( x , y ) .

Fig. 2
Fig. 2

(a) Photograph of investigated airbag cover. The positions are (i) break line, (ii) adhesive label, (iii) stampings within the polymer, and (iv) retainer bars. (b) THz image of the cover showing the peak-to-peak value of the THz signal.

Fig. 3
Fig. 3

(a) THz signal for a reference measurement through air and the airbag cover. The peak-to-peak value (PP) as figure of merit is illustrated. (b) Measured signal at the break line exhibiting a double pulse shape, allowing determination of the two time differences Δ t 1 and Δ t 2 .

Fig. 4
Fig. 4

Scheme of the cross-polarization geometry. The emitted THz wave is polarized perpendicularly (along x axis) to the detector’s accepted polarization (along y axis). If a birefringent sample is placed within the THz beam path, the THz wave is rotated (by Δ φ ) and a signal can be detected.

Fig. 5
Fig. 5

(a) Photograph of the fiber-reinforced polymer. At the edges of the sample, the fibers are expected to be oriented parallel to the edges, as at positions I and II. (b) Corresponding THz image showing the peak-to-peak value of the THz signal. The pronounced orientation of the fibers at the edges can be identified by the increased THz signal.

Fig. 6
Fig. 6

THz signal for two positions of the fiber reinforced polymer (pixels I and II; cf. Fig 5). Depending on the orientation of the fibers the THz wave is rotated clockwise or counterclockwise. At the time position T max , the THz signal exhibits its maximum at pixel I and its minimum at pixel II.

Fig. 7
Fig. 7

THz image of the fiber reinforced sample showing the amplitude value at the time T max . At the upper edge, the value is positive, since the THz wave is rotated counterclockwise due to the fiber orientation, while the wave is rotated clockwise and the amplitude is negative.

Fig. 8
Fig. 8

Three waveforms measured one after another. The deviation between the individual time traces is below 1%.

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