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大气湍流和成像系统噪声的存在使得观测的扩展目标图像退化、扭曲,进而无法辨认其细节。目前,常采用自适应光学技术实时去除由于大气湍流带来的像差。以61单元变形镜作为校正器,随机并行梯度下降算法作为无波前探测自适应光学系统的控制算法,扩展目标图像灰度值的方差函数作为控制算法优化的性能指标函数,建立无波前探测自适应光学系统仿真模型,分析成像系统噪声对无波前探测自适应光学校正效果的影响。结果表明,当像差较小且图像信噪比大于20 dB时,自适应光学技术的校正效果几乎不受影响;但随着信噪比的减小,校正效果对比无噪声时明显变差。相同的信噪比条件下,像差越大,成像效果受噪声的影响越大。
Atmospheric turbulence and the presence of imaging system noise degrade and distort the observed extended target image, making it impossible to discern its details. Currently, adaptive optics are often used to remove in real time the aberrations caused by atmospheric turbulence. A 61-unit anamorphic mirror was used as a corrector and a random-parallel gradient descent algorithm was used as a control algorithm of the adaptive optical system without wavefront detection. The variance function of the gray value of the target image was expanded as a performance index function for the optimization of the control algorithm. Adaptive optical system simulation model to analyze the influence of imaging system noise on adaptive optical correction without wavefront detection. The results show that the correction effect of adaptive optics is almost unaffected when the image aberration is small and the image SNR is more than 20 dB; however, the correction effect is obviously worse than the noise-free when the signal-to-noise ratio decreases. The same signal-to-noise ratio conditions, the greater the aberration, the imaging effect of the greater the impact of noise.