Enhancement of azimuth measurement accuracy under cloud and fog via fusion of Multi-Topological-Charge information of vortex beams

Vortex beams carry orbital angular momentum (OAM), and their phase spectra can be exploited for target azimuth measurement. However, in scattering environments such as cloud and fog, both intensity and phase information are severely distorted, leading to degraded azimuth measurement accuracy. To address this issue, we extended the conventional azimuth measurement method based on the OAM phase spectrum of vortex beams with topological charges in the range of [-l₀, l₀] to vortex beams with same-sign topological charges. Simultaneously, by fusing information from multiple topological charges, the loss of target intensity images caused by the hollow intensity distribution is reduced, enabling joint correction of the intensity and phase distributions under cloud and fog conditions. This approach avoids interference from vortex beams with opposite-sign topological charges, thus significantly improving the accuracy of target azimuth measurement. The results demonstrated that the proposed method significantly improved azimuth measurement accuracy under various conditions. After denoising, the azimuth error for a single target was reduced from 13.26^° to 1.27^°. When extended to multi-target detection, the peak signal-to-noise ratio (PSNR) increased from 26.02 dB to 53.95 dB, and the corresponding azimuth errors were reduced from [26.35^°,12.56^°,20.25^°] to [0.72^°,1.48^°,0.81^°], respectively. These results indicate that the proposed approach effectively exploits intensity distribution differences among vortex beams with different topological charges, thereby improving azimuth measurement accuracy in scattering environments. The method shows promising potential for target azimuth detection in complex environments.