Mitigation of atmospheric turbulence effects on ISAL imaging by real-time adaptive optics compensation

The Inverse synthetic aperture ladar (ISAL) is an important technique for high resolution imaging at a long range. However, mitigating atmospheric turbulence effects remains a significant challenge in practical applications. Unlike previous studies, we investigate whether real-time adaptive optics (AO) can correct the turbulence-induced phase fluctuations at the receiving end in the ISAL process both in the spatial and temporal domains. We show that using real-time AO including phase unwrapping can correct the phase fluctuation of the echo signal. We also use a phase gradient autofocus (PGA) algorithm with a range-Doppler (R-D) algorithm to correct the piston phase error in slow-time domain. The synergistic combination of AO technology and PGA algorithms presents what we believe to be a novel approach to effectively mitigate the atmospheric turbulence-induced distortions in ISAL imaging, even under strong turbulence conditions. Besides, simulation results demonstrate that the AO bandwidth significantly influences ISAL processing performance. Target imaging quality can be effectively achieved when the AO bandwidth exceeds 60 Hz, even under strong turbulence conditions.