Airborne three-line mid-IR DIAL for rapid chemical species plume mapping

Coherent Technologies, Inc. has recently designed and developed an airborne Differential Absorption Lidar (DIAL) sensor that can rapidly and economically locate, identify, and quantitatively map hazardous chemical releases. The lidar was built under contract from Eastman Kodak Company and is capable of filling a broad range of chemical measurement needs. Topographic returns are used to provide simultaneous column content measurement of two (possibly three) chemical species with absorption features between approximately 2.4 microns and 3.5 microns. The system incorporates platform attitude correction and is optimized for mapping surface-source chemical plumes within swaths exceeding 50 m. This system can provide ground resolution better than 1 m at flight speeds in excess of 75 m/s. The 14-month transceiver design-and-build effort is currently in the final integration phase, and flight-testing is scheduled to begin this summer. A recently developed species-specific plume model developed by Kodak, enables reconstruction of the altitude distribution of the chemical plume and estimation of the source release rate, as well as providing realistic species-specific sensor performance predictions under differing environmental conditions. The paper discusses the system architecture, performance modeling, technology trades, and current status, and demonstrates the system measurement capabilities using modeled HCl plumes.