18 September 2014 Phase error suppression by low-pass filtering for synthetic aperture imaging ladar
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Compared to synthetic aperture radar (SAR), synthetic aperture imaging ladar (SAIL) is more sensitive to the phase errors induced by atmospheric turbulence, undesirable line-of-sight translation-vibration and waveform phase error, because the light wavelength is about 3-6 orders of magnitude less than that of the radio frequency. This phase errors will deteriorate the imaging results. In this paper, an algorithm based on low-pass filtering to suppress the phase error is proposed. In this algorithm, the azimuth quadratic phase history with phase error is compensated, then the fast Fourier transform (FFT) is performed in azimuth direction, after the low-pass filtering, the inverse FFT is performed, then the image is reconstructed simultaneously in the range and azimuth direction by the two-dimensional (2D) FFT. The highfrequency phase error can be effectively eliminated hence the imaging results can be optimized by this algorithm. The mathematical analysis by virtue of data-collection equation of side-looking SAIL is presented. The theoretical modeling results are also given. In addition, based on this algorithm, a principle scheme of optical processor is proposed. The verified experiment is performed employing the data obtained from a SAIL demonstrator.
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Zhiwei Sun, Zhiwei Sun, Peipei Hou, Peipei Hou, Ya'nan Zhi, Ya'nan Zhi, Jianfeng Sun, Jianfeng Sun, Yu Zhou, Yu Zhou, Qian Xu, Qian Xu, Zhiyong Lu, Zhiyong Lu, Liren Liu, Liren Liu, } "Phase error suppression by low-pass filtering for synthetic aperture imaging ladar", Proc. SPIE 9227, Unconventional Imaging and Wavefront Sensing 2014, 92270F (18 September 2014); doi: 10.1117/12.2060472; https://doi.org/10.1117/12.2060472

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