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Applied Optics

Applied Optics


  • Vol. 43, Iss. 30 — Oct. 20, 2004
  • pp: 5637–5646

Terahertz imaging system based on a backward-wave oscillator

Adrian Dobroiu, Masatsugu Yamashita, Yuichi N. Ohshima, Yasuyuki Morita, Chiko Otani, and Kodo Kawase  »View Author Affiliations

Applied Optics, Vol. 43, Issue 30, pp. 5637-5646 (2004)

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We present an imaging system designed for use in the terahertz range. As the radiation source a backward-wave oscillator was chosen for its special features such as high output power, good wave-front quality, good stability, and wavelength tunability from 520 to 710 GHz. Detection is achieved with a pyroelectric sensor operated at room temperature. The alignment procedure for the optical elements is described, and several methods to reduce the etalon effect that are inherent in monochromatic sources are discussed. The terahertz spot size in the sample plane is 550 μm (nearly the diffraction limit), and the signal-to-noise ratio is 10,000:1; other characteristics were also measured and are presented in detail. A number of preliminary applications are also shown that cover various areas: nondestructive real-time testing for plastic tubes and packaging seals; biological terahertz imaging of fresh, frozen, or freeze-dried samples; paraffin-embedded specimens of cancer tissue; and measurement of the absorption coefficient of water by use of a wedge-shaped cell.

© 2004 Optical Society of America

OCIS Codes
(120.4290) Instrumentation, measurement, and metrology : Nondestructive testing
(150.3040) Machine vision : Industrial inspection
(170.0110) Medical optics and biotechnology : Imaging systems
(170.3880) Medical optics and biotechnology : Medical and biological imaging
(230.7020) Optical devices : Traveling-wave devices
(260.3090) Physical optics : Infrared, far

Original Manuscript: April 7, 2004
Revised Manuscript: August 12, 2004
Published: October 20, 2004

Adrian Dobroiu, Masatsugu Yamashita, Yuichi N. Ohshima, Yasuyuki Morita, Chiko Otani, and Kodo Kawase, "Terahertz imaging system based on a backward-wave oscillator," Appl. Opt. 43, 5637-5646 (2004)

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