One of the main challenges in remote Fourier transform infrared (FT-IR) spectroscopy is the collection of a
reliable background spectrum. Although suggested as a method to address the problem in prior literature,
super clip apodization (SCA) has had little reported success for wide spectral features. SCA is a technique that
involves the manipulation of different parts of the interferogram to calculate an absorbance spectrum from a
single interferogram. A new method called complementary super clip apodization (CSCA) is developed here and
is successfully used in conjunction with SCA in an iterative optimization algorithm. The umbrella term of <i>super
clip mathematics</i> is also defined to encompass spectral calculation using SCA, CSCA or both in combination.
The validity of <i>super clip mathematics</i> is demonstrated in an experimental study of gas-phase nitromethane. In
an effort to mimic errors present in standoff detection, uniformly distributed noise and/or wavenumber shifting
is added to the interferometric sample data to test the robustness of the algorithm. It will be shown that the
implementation of SCA and CSCA in combination is more successful for concentration assessment than using
SCA or CSCA alone.
A consortium of researchers at University of New South Wales (UNSW@ADFA), and Loyola University New
Orleans (LU NO), together with Australian government security agencies (e.g., Australian Federal Police), are
working to develop highly sensitive laser-based forensic sensing strategies applicable to characteristic substances
that pose chemical, biological and explosives (CBE) threats. We aim to optimise the potential of these strategies
as high-throughput screening tools to detect prohibited and potentially hazardous substances such as those
associated with explosives, narcotics and bio-agents.