An Estimation Theory Approach to Detection and Ranging of Obscured Targets in 3-D LADAR Data

The purpose of this research is to develop an algorithm to detect obscured images in 3-D LADAR data. The real data used for this research was gathered using a FLASH LADAR system under development at AFRL/SNJM. The system transmits light with a wavelength of 1.55 micrometers and produces 20 128 X 128 temporally resolved images from the return pulse separated by less than 2 nanoseconds in time. New algorithms for estimating the range to a target in 3-D FLASH LADAR data were developed. Results from processing real data are presented and compared to the traditional correlation receiver for extracting ranges to the target. This research shows that the algorithms presented are capable of distinguishing two surfaces separated by only 40 inches using real data

Laser Illuminated Imaging: Multiframe Beam Tilt Tracking and Deconvolution Algorithm

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\u27s 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