19 May 2005 Demonstration of synthetic aperture imaging ladar
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Proceedings Volume 5791, Laser Radar Technology and Applications X; (2005); doi: 10.1117/12.609682
Event: Defense and Security, 2005, Orlando, Florida, United States
Abstract
The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range, two-dimensional imaging with modest aperture diameters. This paper details our laboratory-scale SAIL testbed, digital signal processing techniques, and image results. A number of fine-resolution, well-focused SAIL images are shown including both retro-reflecting and diffuse scattering targets. A general digital signal processing solution to the laser waveform instability problem is described and demonstrated, involving both new algorithms and hardware elements. These algorithms are primarily data-driven, without a priori knowledge of waveform and sensor position, representing a crucial step in developing a robust imaging system. These techniques perform well on waveform errors, but not on external phase errors such as turbulence or vibration. As a first step towards mitigating phase errors of this type, we have developed a balanced, quadrature phase, laser vibrometer to work in conjunction with our SAIL system to measure and compensate for relative line of sight motion between the target and transceiver. We describe this system and present a comparison of the vibrometer-measured phase error with the phase error inferred from the SAIL data.
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W. Buell, N. Marechal, J. Buck, R. Dickinson, D. Kozlowski, T. Wright, S. Beck, "Demonstration of synthetic aperture imaging ladar", Proc. SPIE 5791, Laser Radar Technology and Applications X, (19 May 2005); doi: 10.1117/12.609682; https://doi.org/10.1117/12.609682
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KEYWORDS
Vibrometry

Imaging systems

Oscillators

Phase measurement

LIDAR

Algorithm development

Image processing

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