Visible/near-infrared hyperspectral sensing of solids under controlled environmental conditions

We describe the use of a wind tunnel for conducting controlled passive hyperspectral imaging experiments. In recent years, passive hyperspectral detection of solids, minerals and ores has emerged as a very useful technique, for example for classifying land types, mineral deposits, and agricultural practices. Such techniques are also potentially useful for detecting explosives, solid-phase chemicals and other materials of interest from a distance so as to provide operator safety. The Pacific Northwest National Laboratory operates a wind tunnel facility that can generate and circulate artificial atmospheres whereby certain environmental parameters can be controlled such as lighting, humidity, temperature, aerosol and obscurant burdens. By selecting the appropriate fore-optics and sample size, one can conduct meaningful experiments under controlled conditions at relatively low cost when compared to typical field deployments. We will present recent results describing optimized sensing of solids over tens of meters distance using both visible and near-infrared cameras, as well as the effects of certain environmental parameters on data retrieval.