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Proceedings Paper

Improved terahertz imaging with a sparse synthetic aperture array
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Paper Abstract

Sparse arrays are highly attractive for implementing two-dimensional arrays, but come at the cost of degraded image quality. We demonstrate significantly improved performance by exploiting the coherent ultrawideband nature of singlecycle THz pulses. We compute two weighting factors to each time-delayed signal before final summation to form the reconstructed image. The first factor employs cross-correlation analysis to measure the degree of walk-off between timedelayed signals of neighboring elements. The second factor measures the spatial coherence of the time-delayed delayed signals. Synthetic aperture imaging experiments are performed with a THz time-domain system employing a mechanically scanned single transceiver element. Cross-sectional imaging of wire targets is performed with a onedimensional sparse array with an inter-element spacing of 1.36 mm (over four λ at 1 THz). The proposed image reconstruction technique improves image contrast by 15 dB, which is impressive considering the relatively few elements in the array. En-face imaging of a razor blade is also demonstrated with a 56 x 56 element two-dimensional array, showing reduced image artifacts with adaptive reconstruction. These encouraging results suggest that the proposed image reconstruction technique can be highly beneficial to the development of large area two-dimensional THz arrays.

Paper Details

Date Published: 18 February 2010
PDF: 8 pages
Proc. SPIE 7601, Terahertz Technology and Applications III, 760103 (18 February 2010); doi: 10.1117/12.841756
Show Author Affiliations
Zhuopeng Zhang, Univ. of Delaware (United States)
Takashi Buma, Univ. of Delaware (United States)

Published in SPIE Proceedings Vol. 7601:
Terahertz Technology and Applications III
Laurence P. Sadwick; Creidhe M. M. O'Sullivan, Editor(s)

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