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6 January 2020 Far-field laser spot image detection for use under atmospheric turbulence
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In wireless laser communication, the effects of atmospheric turbulence cause laser spots to appear as irregular speckles in the far-field plane, which may make automatic acquisition, pointing, and tracking systems unable to locate a spot position. We propose an innovative and precise anti-interference, spot-detection algorithm for far-field irregular speckles based on the intensity characteristics of the far-field spots. Before obtaining the spot center coordinates through two-dimensional vector space circle fitting, the proposed algorithm employs computer graphics combined with mathematical morphology to fill the connected domains and extracts light-spot edges using the Canny operator, thus resulting in an accurate detection of far-field spots. The algorithm validation, using an automated experimental platform (atmospheric turbulent refractive-index structure parameter Cn2 is 10  −  15  m  −  2/3), yields a detection threshold accuracy of 30 to 32 pixels (each pixel represents 3  μrad) for 10.2 km far-field spot images. The corresponding deviation satisfies the two-dimensional aiming platform for a minimum step distance of 17.45  μrad, verifying the feasibility and effectiveness of the algorithm.

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2020/$28.00 © 2020 SPIE
XiZheng Ke and Yongkang Jing "Far-field laser spot image detection for use under atmospheric turbulence," Optical Engineering 59(1), 016103 (6 January 2020).
Received: 30 July 2019; Accepted: 16 December 2019; Published: 6 January 2020

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