A novel method, to the best of our knowledge, for mitigating thermal blooming by using the rotating beam when propagating in the atmosphere is proposed. The rotating beam, generated by coherent superposition of two vortex beams with opposite topological charges and frequency shift, can directly modulate the heat source in time and then mitigate the thermal blooming in the atmosphere. The theoretical model of the rotating beam propagating in the atmosphere has been established, and the thermal blooming effects of the rotating beam and the conventional nonrotating beam through the atmosphere have been analyzed and compared. Results indicate that, compared to the nonrotating beam propagating in the atmosphere, the rotating beam is less affected by the thermal blooming and exhibits outstanding performance in mitigating the thermal blooming effect, resulting in smaller beam expansion, less shift of the beam centroid position, and better beam quality than those of the nonrotating beam.
The wavefront sensor plays an important role in the adaptive optics (AO) system for aero-optical distortion correction. However, the bandwidth of the current data interfaces of wavefront sensors, as one of the key factors, limits applications of the AO system in extremely high-frequency aero-optical distortion correction, leading to unsatisfactory performance. In this paper, a framework for wavefront data compression using compressed sensing is established to improve the correction ability of the AO system, and a disturbed Zernike gradient dictionary (DZGD) learning over the k-singular value decomposition algorithm is proposed for achieving good performance in the compression of aero-optical wavefront data. Based on the proposed DZGD, a method for aero-optical distortion data compression and wavefront reconstruction is developed that can efficiently reduce the amount of data in the information channel without degradation of the correction effect in aero-optical distortion correction. The compressibility of aero-optical distortions over the DZGD is analyzed in detail by numerical simulations. In addition, the selection criteria of the measurement matrix and the anti-noise characteristic of the method are also discussed. Data compression using our method is feasible and highly adaptable in the correction of aero-optical distortions, and exhibits stronger resistance against detector noise compared with using the conventional dictionary.
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