18 May 2005 Terahertz signature characterization of bio-simulants
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Collaboration with the University of Virginia (UVa) and the University of California, Santa Barbara (UCSB) has resulted in the collection of signature data in the THz region of the spectrum for ovalbumin, Bacillus Subtilis (BG) and RNA from MS2 phage. Two independent experimental measurement systems were used to characterize the bio-simulants. Prior to our efforts, only a limited signature database existed. The goal was to evaluate a larger ensemble of biological agent simulants (BG, MS2 and ovalbumin) by measuring their THz absorption spectra. UCSB used a photomixer spectrometer and UVa a Fourier Transform spectrometer to measure absorption spectra. Each group used different sample preparation techniques and made multiple measurements to provide reliable statistics. Data processing culminated in applying proprietary algorithms to develop detection filters for each simulant. Through a covariance matrix approach, the detection filters extract signatures over regions with strong absorption and ignore regions with large signature variation (noise). The discrimination capability of these filters was also tested. The probability of detection and false alarm for each simulant was analyzed by each simulant specific filter. We analyzed a limited set of Bacillus thuringiensis (BT) data (a near neighbor to BG) and were capable of discriminating between BT and BG. The signal processing and filter construction demonstrates signature specificity and filter discrimination capabilities.
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Alexander J. Majewski, Alexander J. Majewski, Peter Miller, Peter Miller, Rene Abreu, Rene Abreu, Jeffrey Grotts, Jeffrey Grotts, Tatiana Globus, Tatiana Globus, Elliott Brown, Elliott Brown, } "Terahertz signature characterization of bio-simulants", Proc. SPIE 5790, Terahertz for Military and Security Applications III, (18 May 2005); doi: 10.1117/12.603658; https://doi.org/10.1117/12.603658

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