This paper describes a rapid, reagentless, standoff method of detection and classification of bulk and trace suspicious substances on natural surfaces using solar-blind deep UV excitation and detection. Detection is typically accomplished in less one second. The detection method is solar blind and can be employed at standoff distances up to 5 m or more without interference from natural or man-made light sources. By this method, unknown suspicious powders, that potentially contain biological hazards, are automatically triaged using a four-step sequential iteration of Principal Component Analysis methods using pre-determined eigenvector sets to: 1) detect and differentiate whether a sample is bio or non-bio; 2) whether the detected bio is microbial, protein, or plant; 3) if microbial, whether the sample is a bacterial cell or spore, yeast, fungi, or fungal spore; and 4) to provide some higher level of cellular differentiability. The same method is also applicable to a wide range of chemical agents and explosives materials. The method and related instruments employ sample excitation at 248.6 nm and detection over a spectral range from 250 nm to below 350 nm, a spectral region blind to solar and most man-made light sources. Detection and classification is accomplished in less a few seconds. Sample detection and classification rates can be over 20 per second. Fully integrated and self-contained hand-held instruments are presently under development with an overall weight less than about 8 lbs, including a battery for over 8 hours of typical use. The standoff detection range is nominally 5 cm to 5 m.
W. F. Hug, R. Bhartia, K. Sijapati, Q. Nguyen, P. Oswal, and R. D. Reid, "Rapid optical detection and classification of microbes in suspicious powders," Proc. SPIE 10629, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIX, 106290J (Presented at SPIE Defense + Security: April 16, 2018; Published: 16 May 2018); https://doi.org/10.1117/12.2299856.
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