Passive standoff detection of liquid surface contaminants: recent results with CATSI

Abstract

Laboratory and field measurements for the passive standoff detection of liquid contaminants deposited on surfaces are presented. The measurements were performed at the SURFCON trials held at DRDC Suffield in September 2002. The goal of this trial was to verify that passive LWIR spectrometric sensors have the potential for remotely detecting surface contaminants. Laboratory and field data obtained with the passive CATSI sensor are analyzed. For laboratory measurements, variable amounts of liquid H-contaminant were deposited on high-reflectivity and low-reflectivity surfaces of aluminum and Mylar. Field measurements were performed at a standoff distance of 60 m on aluminium plates covered with the H-contaminant and on low-reflectivity surfaces (armored personnel carrier surface and sod). Results indicate that contaminants deposited on high-reflectivity surfaces can be detected, identified and possibly quantified. The contaminants deposited on low-reflectivity surfaces can usually be detected but cannot be identified based on simple correlations with the absorption spectrum of the contaminant. The inhomogeneous layer model developed to explain the spectral radiance associated with non-uniform contaminant coverage is also presented.