Detection of concealed hazardous materials is a pressing need for the global defense community. To address this need,
the development of reliable and readily-deployable sensing devices is a key area of research. A multitude of infrared
sensing techniques are being studied which allow for reliable sensing of concealed threats. Continued development in
this field is working to increase the selectivity of such infrared sensors, while at the same time reducing their complexity,
size and cost. We have recently developed a biomimetic optical filter based approach, based on human color vision, that
utilizes multiple, broadband, overlapping infrared (IR) filters to clearly discriminate between hazardous target chemicals
and interferents with very similar mid-IR spectral signatures. This technique was extensively studied in order to select
filters which provide optimum selectivity for specific chemical sets. Using this knowledge, we designed and assembled a
gas-phase sensor which uses three broadband mid-IR filters to detect and discriminate between a target chemical, fuel
oil, and various interferents with strongly overlapping IR absorption bands in the carbon – hydrogen stretch region of the
IR absorption spectrum 2700 cm-1 - 3300 cm-1 (3.0 μm - 3.7 μm).
We present an overview of the design and performance of this filter-based system and explore the ability of this system
to detect and discriminate between strongly overlapping target and interferent chemicals. The detection results using the
filter-based system are compared to numerical methods to demonstrate the operation of this methodology. We present
the results of experiments with both target and interferent chemicals present with chemicals both in and out of the
detection set, and discuss future field development and application of this approach.