Terahertz (THz) radiation has many far reaching applications - of specific interest is that many non-metallic
and non-polar substances are transparent in the THz frequency range. This provides many practical uses
for security purposes, where it is possible to detect and determine various substances that may be hidden or
undetectable via conventional methods such as X-rays. In addition to this property, terahertz radiation can
either be used in reflection or transmission modes.
This paper will look into the use of transmission techniques to detect various substances using a terahertz
system. Common materials used in bags and suitcases such as nylon, polycarbonate (PC), and polyethylene
(PE) are tested for transparency. These materials then sandwich various illicit substances, and are scanned
by the terahertz system to obtain spectral data, simulating the probing of a suitcase. The sample materials
are then subtracted from the obtained data, which is then compared with previously obtained data of known
substances, and an examination of features in the sample is carried out to determine if a particular substance
is present in the sample.
Liquid spectroscopy allows analysis of chemical composition and provides a better understanding of the solvation
dynamics of various types of liquids. Although it has been shown that liquid spectroscopy using T-rays is feasible,
liquid water absorption is still considered to be one of the most challenging problems facing THz imaging and
spectroscopy in biomedical applications. The absorption coefficient for liquid water shows a very high THz
absorption, 200 cm-1 at 1 THz. This paper describes a promising novel liquid double-modulated differential
time-domain spectroscopy (Double-modulated DTDS) technique to extract the optical parameters with a dual-thickness
measurement. The described technique improves on the previous work, by replacing the required
sample dithering technique with a rotating spinning wheel resulting in an improved noise performance up to two
orders of magnitude.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.