Coherent Doppler Lidar for Human Motion Detection Under Dense Foliage Obscuration

Heavily foliated environments pose challenges for aerial surveillance systems because dense tree canopy obscures the view from airborne sensors. While direct detect foliage penetrating airborne lidar systems have proven effective at locating fixed structures (trails, buildings, stored vehicles, etc.), these systems struggle to detect moving targets such as humans hidden under heavy foliage. To overcome this challenge, MIT Lincoln Laboratory is investigating the feasibility of an airborne coherent lidar for detecting humans under canopy by sensing the Doppler signature caused by human motion (e.g., walking or working). Toward this end, a two channel 1.5 µm pulsed coherent lidar was constructed and tested in a static downward-looking configuration in a foliated environment. Results from this field test are presented along with system simulation, analysis, and a path toward a fully operational airborne design.