Title: An Electronically Steerable Flash Lidar (ESFL)
Author: Carl Weimer
Organization: Ball Aerospace & Technologies Corporation
Co-Authors: Tanya Ramond, Ingrid Burke, Yongxiang Hu, Michael Lefsky
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 multi-beam steering capability. Steering is achieved via an acousto-optic beam deflector that splits the laser into multiple beams that can be independently accessed and pointed without the need of mechanical scanners or boresight mechanisms. A full demonstration unit of ESFL was completed and successfully tested both in laboratory and aircraft flight tests, as presented at the 2010 ESTF conference. Three weeks of testing on aircraft have now been completed, the data processed to Level 1b, and science analysis of the data for multiple types of forests is being completed. This includes inter-comparison with commercial scanning lidar data. Ground validation work in a prescribed burn region is also being completed. Modeling of the improvement in spatial sampling from a potential orbital version of the instrument was completed and shows a twofold improvement in forest height accuracy of current approaches, and a threefold improvement in collection time. The significant improvement by using cloud avoidance algorithms to point the beams for improving global coverage as a function of region and season has also been analyzed using MODIS data. The instrument was accepted into the NASA Airborne Instrument Technology Transition program, and its performance and reliability are being improved so that it can be used by scientists for broader studies.