A new 'semi-active' method for chemical standoff detection

Tim J. Johnson; Bruce A. Roberts; Gerry P. Morgen; Michael A. Hughes; Corey D. Heitschmidt; James F. Kelly

doi:10.1117/12.515606

27 February 2004 A new 'semi-active' method for chemical standoff detection

Tim J. Johnson, Bruce A. Roberts, Gerry P. Morgen, Michael A. Hughes, Corey D. Heitschmidt, James F. Kelly

Proceedings Volume 5268, Chemical and Biological Standoff Detection; (2004) https://doi.org/10.1117/12.515606
Event: Optical Technologies for Industrial, Environmental, and Biological Sensing, 2003, Providence, RI, United States

Abstract

Pacific Northwest National Laboratory (PNNL) has recently developed a hybrid infrared technique for standoff chemical detection. Active infrared detection typically involves a sender and receiver telescope separated by (100’s) of meters and is quite sensitive, but is extremely cumbersome to align and is extremely sensitive to misalignment as the two telescopes must not only be parallel, but coaxial. Passive infrared sensing offers facile alignment (simply point the input optics), but relies on a happenstance temperature difference ΔT between the chemical plume and its background. Oftentimes the ΔT found in the field is only 1 or 2 K, and the passive method is thus not very sensitive in many cases. The “semi-active” technique creates a large temperature difference ΔT by placing an extended blackbody source at some distance away from the receiver telescope. The blackbody is designed to fill the telescope’s FOV at a typical distance of 100 m, and provides a typical temperature difference ΔT on the order of 80 to 100 K. Design considerations and experimental results in a direct comparison of passive, active, and semi-active measurements will be discussed.

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Tim J. Johnson, Bruce A. Roberts, Gerry P. Morgen, Michael A. Hughes, Corey D. Heitschmidt, and James F. Kelly "A new 'semi-active' method for chemical standoff detection", Proc. SPIE 5268, Chemical and Biological Standoff Detection, (27 February 2004); https://doi.org/10.1117/12.515606

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