Capt. David J. Becker (Air Force Institute of Technology), Stephen C. Cain (Air Force Institute of Technology)
Keywords: SSA
Abstract:
A laser-illuminating imaging system operating in the presence of atmospheric turbulence will encounter several sources of error that can make postprocessing the images difficult. As the beam propagates, turbulence induced tilt will cause the beam to wander off axis from the target. Additionally, the returning beam convoluted with the target will also encounter turbulence induced tilt that appears as apparent movement of the target between image frames. This is especially troublesome in imaging satellites due to most turbulence being closer to the surface and greatly affecting the beam in the early stages of propagation. This results in varying beam intensities at the target surface between imaging frames that increases the SNR of correlated and averaged frames. Using simulated data, an algorithm using expectation maximization and least squares was developed that has the ability to estimate both the tilt of the pulsed laser beam and the apparent movement of the object between incoherent frames separately and produce an estimate of the target. The results from this algorithm can be used to reduce the effects of beam wander and thus increase the SNR of postprocessed images.
Date of Conference: September 11-14, 2012
Track: Poster