Airborne Thermal Infrared Hyperspectral Imaging of Gases

Characterization of gas clouds are challenging situations to address due to the uneven distribution of these large entities as a function of time. Whether gas characterization is carried out for gas leaks surveys or environmental monitoring purposes, explosives and/or toxic chemicals are often involved. In such situations, airborne measurements present distinct advantages over ground based-technics since large areas can be covered efficiently from a safe distance. Most gases are infrared-active and can be probed using infrared imaging. Airborne thermal infrared hyperspectral imaging was carried out above smokestacks and a ground-based gas release experiment in order to illustrate the benefits of this technique to characterize gas clouds. Quantitative airborne chemical images of carbon monoxide (CO) and ethylene (C₂H₄) were obtained from measurements carried out using a midwave (3-5 μm) and a longwave (8-12 μm) airborne infrared hyperspectral sensor respectively. Airborne measurements were carried out using both mapping and targeting acquisition modes. The later provides unique time-dependent information such as the gas cloud direction and velocity.