Efficient terahertz en-face imaging.

In this work, we develop a pulsed terahertz imaging system in reflection geometry, where due to scanning of the terahertz beam neither the sample nor the emitter and detector have to be moved. We use a two mirror galvanoscanner for deflecting the beam, in combination with a single rotationally symmetric focusing lens. In order to efficiently image planar structures, we develop an advanced scanning routine that resolves all bending effects of the imaging plane already during measurement. Thus, the measurement time is reduced, and efficient imaging of surfaces and interfaces becomes possible. We demonstrate the potential of this method in particular for a plastic-metal composite sample, for which non-destructive evaluation of an interface is performed.

[1]  Mira Naftaly,et al.  Methodologies for determining the dynamic ranges and signal-to-noise ratios of terahertz time-domain spectrometers. , 2009, Optics letters.

[2]  David Zimdars,et al.  Portable video rate time domain terahertz line imager for security and aerospace nondestructive examination , 2010, Defense + Commercial Sensing.

[3]  Jingzhou Xu,et al.  A real-time terahertz wave imager , 2008, 2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science.

[4]  E. Linfield,et al.  Terahertz pulse imaging in reflection geometry of human skin cancer and skin tissue. , 2002, Physics in medicine and biology.

[5]  Martin Koch,et al.  Confocal THz Laser Microscope , 2009 .

[6]  B. Fischer,et al.  Dynamic range in terahertz time-domain transmission and reflection spectroscopy. , 2005, Optics letters.

[7]  Vincent P Wallace,et al.  Three-dimensional imaging of optically opaque materials using nonionizing terahertz radiation. , 2008, Journal of the Optical Society of America. A, Optics, image science, and vision.

[8]  Yaochun Shen,et al.  Terahertz pulsed spectroscopy and imaging for pharmaceutical applications: a review. , 2011, International journal of pharmaceutics.

[9]  Xiang Zhang,et al.  Terahertz beam generation by femtosecond optical pulses in electro‐optic materials , 1992 .

[10]  Qing Hu,et al.  Real-time, continuous-wave terahertz imaging by use of a microbolometer focal-plane array. , 2005, Optics letters.

[11]  D. Mittleman,et al.  Noncontact semiconductor wafer characterization with the terahertz Hall effect , 1997 .

[12]  R. Jacobsen,et al.  Generation and detection of terahertz pulses from biased semiconductor antennas , 1996 .

[13]  M. Koch,et al.  Terahertz imaging: a new non-destructive technique for the quality control of plastic weld joints , 2007 .

[14]  Yan Zhang,et al.  Detection and identification of illicit drugs using terahertz imaging , 2006 .

[15]  Qi Wang,et al.  Real-time terahertz scanning imaging by use of a pyroelectric array camera and image denoising. , 2010, Journal of the Optical Society of America. A, Optics, image science, and vision.

[16]  X-C Zhang,et al.  Identification and classification of chemicals using terahertz reflective spectroscopic focal-plane imaging system. , 2006, Optics express.

[17]  Irl N. Duling,et al.  High speed imaging with time domain terahertz , 2010, 35th International Conference on Infrared, Millimeter, and Terahertz Waves.

[18]  Martin Koch,et al.  Terahertz spectroscopy on adhesive bonds , 2011 .

[19]  B. Ferguson,et al.  T-ray computed tomography. , 2002, Optics letters.

[20]  Joachim Jonuscheit,et al.  A pulsed THz imaging system with a line focus and a balanced 1-D detection scheme with two industrial CCD line cameras , 2010, CLEO/QELS: 2010 Laser Science to Photonic Applications.

[21]  M. Nuss,et al.  Imaging with terahertz waves. , 1995, Optics letters.

[22]  C. Otani,et al.  Terahertz imaging with a direct detector based on superconducting tunnel junctions , 2006 .

[23]  Takeshi Yasui,et al.  Real-time terahertz color scanner for moving objects. , 2008, Optics express.

[24]  A. Tünnermann,et al.  Terahertz line detection by a microlens array coupled photoconductive antenna array. , 2008, Optics Express.

[25]  D. Grischkowsky,et al.  Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors , 1990 .

[26]  N. Vieweg,et al.  Terahertz imaging: applications and perspectives. , 2010, Applied optics.

[27]  P. Taday,et al.  Detection and identification of explosives using terahertz pulsed spectroscopic imaging , 2005 .

[28]  Wolfgang Boehler,et al.  Investigating Laser Scanner Accuracy , 2005 .

[29]  Z Jiang,et al.  2D measurement and spatio-temporal coupling of few-cycle THz pulses. , 1999, Optics express.

[30]  D. Auston.  Picosecond optoelectronic switching and gating in silicon , 1975 .

[31]  K. Kawase,et al.  Non-destructive terahertz imaging of illicit drugs using spectral fingerprints. , 2003, Optics express.

[32]  W. R. Tribe,et al.  Security applications of terahertz technology , 2003, SPIE Defense + Commercial Sensing.

[33]  Masayoshi Tonouchi,et al.  Cutting-edge terahertz technology , 2007 .

[34]  M. Koch,et al.  Terahertz spectroscopy and imaging – Modern techniques and applications , 2011 .

[35]  Xiang Zhang,et al.  Terahertz optical rectification from 〈110〉 zinc‐blende crystals , 1994 .

[36]  M. Koch,et al.  Detection of foreign bodies in chocolate with pulsed terahertz spectroscopy , 2008 .

[37]  Wai Lam Chan,et al.  Imaging with terahertz radiation , 2007 .

[38]  X. Zhang,et al.  Broadband detection capability of ZnTe electro-optic field detectors , 1996 .

[39]  Development of laser scanning terahertz imaging system using organic nonlinear optical crystal , 2010, 35th International Conference on Infrared, Millimeter, and Terahertz Waves.

[40]  Yan Zhang,et al.  Terahertz quasi-near-field real-time imaging , 2009 .

[41]  Xiang Zhang,et al.  Two‐dimensional electro‐optic imaging of THz beams , 1996 .

[42]  Cunlin Zhang,et al.  Compact continuous-wave subterahertz system for inspection applications , 2005 .