Development of FireLidar: an active imaging system for smoke and flame environments

Abstract

FireLidar, an active optical imaging system, is being developed for use as an aid to search and rescue in smoke and flame environments. The system is intended to augment currently available passive thermal imaging technology by imaging in the presence of a thermal bloom, heavy smoke conditions, or species which strongly absorb thermal radiation, such as water. We present experimental verification of a theoretical model for FireLidar. Lidar range equations for compartment fire scenarios are derived and compared to measurements taken in a controlled smoke chamber. Extinction measurements of near-infrared light through soot particulate provide information about optical properties of fire environments necessary to predict Lidar returns. Measured extinction values are compared to a singlescattering approximation, based on the Rayleigh-Debye-Gans scattering theory for fractal aggregates. Component specifications for a FireLidar prototype system are discussed, including laser power, filter bandwidth, and camera integration times. A man-portable prototype system using specified components is scheduled for completion by the end of 2005, with a handheld device following soon thereafter.