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This paper describes the development status of a standoff handheld sensor for real-time assessment of trace chemical, biological, and explosives materials on surfaces, which is an important capability needed by warfighters/first responders for situational awareness of hazards in their proximity. It is important to perform these assessments without contact or spreading of substances or use of reagents. This work was conducted under Army, DTRA, and DHS funding to develop a Standoff Hand-held CBE (SHCBE) optical sensor which detects and classifies trace and bulk concentrations of a wide range of CBE materials on surfaces at distances of 1 to 5 m in real-time and full daylight with a fully integrated analyzer. The sensor method combines independent but complementary chemical information of molecular bonds within a targeted material using Raman and electronic configuration information of the material using fluorescence, both with excitation below 250 nm. There are seven primary advantages of the SHCBE detection method compared to near-UV, visible or near-IR counterparts: 1) Solar blind detection enabling standoff operation in full daylight; 2) Fluorescence-free Raman and Raman-free fluorescence enabling enhanced detection and identification of target materials without mutual interference; 3) Resonance Raman signal enhancement for improved Raman sensitivity; 4) Simplification of Raman spectra due to resonance enhancement, 5) Short penetration depth, providing physical separation of surface contaminant materials from substrate; 6) no damage to sensitive organic and biological materials, due to laser pulse width related sample heating, and 7) eye retina safe. These capabilities are not possible with near UV, visible, or near IR sensors. A special feature of our sensor is the ability to detect trace biological materials at standoff distances in real time with a handheld device. Photon Systems has developed these methods over many years, enabling instruments deployed to extreme environments on Earth and the SHERLOC instrument which has been successfully operating on Mars on the Perseverance Rover since it landed on Feb. 18, 2021
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