Robust Identification of Concealed Dangerous Substances by Spectral Correlation of Terahertz Transmission Images
Journal article, Peer reviewed
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http://hdl.handle.net/11250/2367466Utgivelsesdato
2015Metadata
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- Publikasjoner fra CRIStin - NTNU [38672]
Originalversjon
Terahertz Science and Technology, IEEE Transactions on 2015, 5(3):438-444 10.1109/TTHZ.2015.2400224Sammendrag
Terahertz images containing spectral information in
each pixel are recorded in transmission mode using a fibercoupled
time-domain spectroscopy system. The images are acquired
by mounting a sample holder on an x–y stage, which
is stepped across the beam in the two transverse directions,
while the transmitted THz waveform is captured. The materials
under investigation consist of uncovered and hidden samples of
an explosive (RDX) and simulants (lactose and tartaric acid).
Spectral angle mapping is used to identify the materials in the
Terahertz images by comparing the spectrum in each pixel with
a library of reference spectra for the different materials. We
test the performance of several spectral characteristics derived
from the measured transmission spectra. Robustness is studied
by investigating the Receiver-Operating-Characteristics (ROCs).
The ROCs are used to find which of the spectral characteristics is
most robust to different sample preparation conditions, without
the need for extensive pre-treatment of the data, such as baseline
correction. Simple theoretical considerations are used to support
the experimental results.