An Electronically Steerable Flash Lidar (ESFL)

Current space-based lidar systems for Earth remote sensing have a number of inherent limitations that impact their use for broader science applications. These include no cross-track coverage, fixed spatial sampling that forces pointing control to be performed by the spacecraft, cloud loss over many types of scenes, and, in general, lifetimes set in part by the number of laser shots fired. The Electronically Steerable Flash Lidar (ESFL) is a new concept developed to help in overcoming these limitations. It combines a new “Flash” focal plane technology that allows both imaging and waveform ranging, with a multibeam steering capability. Steering is achieved via an acoustooptic beam deflector that splits the laser into multiple beams that can be independently accessed and pointed without the need for mechanical scanners or boresight mechanisms. A full demonstration unit of ESFL was completed and successfully tested both in laboratory and aircraft flight tests. One to ten beams were controlled at the full frame rate (30Hz) of the focal plane. Laboratory testing showed that ESFL can be used to point between clouds identified by a separate visible camera. Multiple operating modes were demonstrated including a geolocation mode where a beam tracked a pre-defined transect defined by its GPS determined latitude/longitude as the aircraft carrying the lidar passed over. ESFL was flight tested over a broad range of land and forest scenes illustrating its ability to terrain map as well as profile forest canopies. NASA ESTO Grant # NNX0AN37G Co-Investigators: Ingrid Burke, Yongxiang Hu, Michael Lefsky