Distorted Laser Spot Center Positioning Based on Captured Image Under Laser-Camera Misalignment in UOWC

The laser spot center positioning is an essential step for camera-based terminal positioning and alignment in a long-distance laser-based underwater optical wireless communication (UOWC) system. In this paper, the laser spot profile distorted by laser-camera misalignment is examined and a principal component analysis (PCA)-based spot center estimation algorithm is proposed. The centroid offset of the distorted laser spot under different deflection angles, transmitted optical powers and camera exposure values is experimentally demonstrated and analyzed. The estimation performance and the impact of the three parameters are also studied. Experimental results show that the proposed PCA-based algorithm significantly outperforms conventional gray centroid-based positioning method under different conditions.