Laser Illuminated Imaging: Multiframe Beam Tilt Tracking and Deconvolution Algorithm.

摘要

A laser-illuminated imaging system operating in the presence of atmospheric turbulence will encounter several sources of noise and diffraction induced errors. As the beam propagates, turbulence induced tilt will cause the beam to wander off axis from the target. This is especially troublesome when imaging satellites, since most turbulence is closer to the Earth's surface and greatly affects the beam in the early stages of propagation. Additionally, the returning beam convolved with the target will encounter turbulence induced tilt that appears as apparent movement of the target between image frames. This results in varying beam intensities at the target surface between imaging frames that can affect registration algorithms and tracking. In this research effort, an algorithm using expectation maximization and least squares techniques was developed that has the ability to separately estimate both the tilt of the pulsed laser beam and the apparent movement of the object between incoherent frames and produce a superior image estimate of the target and provide tracking information. The results from this algorithm can be used to reduce the effects of beam wander and increase the SNR of post-processed images.