The spatial resolution of a conventional imaging laser radar system is constrained by the diffraction limit of the telescope's aperture. We investigate a technique known as synthetic-aperture imaging laser radar (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. We detail our laboratory-scale SAIL testbed, digital signal-processing techniques, and image results. In particular, we report what we believe to be the first optical synthetic-aperture image of a fixed, diffusely scattering target with a moving aperture. A number of fine-resolution, well-focused SAIL images are shown, including both retroreflecting and diffuse scattering targets, with a comparison of resolution between real-aperture imaging and synthetic-aperture imaging. 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.
© 2005 Optical Society of America
(100.2000) Image processing : Digital image processing
(100.3010) Image processing : Image reconstruction techniques
(110.0110) Imaging systems : Imaging systems
(280.3640) Remote sensing and sensors : Lidar
(280.6730) Remote sensing and sensors : Synthetic aperture radar
Steven M. Beck, Joseph R. Buck, Walter F. Buell, Richard P. Dickinson, David A. Kozlowski, Nicholas J. Marechal, and Timothy J. Wright, "Synthetic-aperture imaging laser radar: laboratory demonstration and signal processing," Appl. Opt. 44, 7621-7629 (2005)