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为提高薄膜菲涅耳透镜成像性能,采用无波前传感的自适应光学系统对菲涅耳透镜点目标成像的波前像差进行实验校正.像差校正控制采用随机并行梯度下降算法,以远场光斑像清晰度函数为优化指标,算法迭代数十次后收敛.系统闭环校正后,焦平面光斑等效半径缩小了43%,二阶矩为0.997 5,接近理想极限1,像清晰函数值和峰值光强提高了一倍,光强的半高全宽达到1.2倍衍射极限,调制传递函数的中频分量显著提高.实验结果表明该方法结实现构简单,能快速、有效地校正菲涅耳透镜波前像差,改善系统的成像性能,可应用于大口径、轻量化的空间望远镜.
In order to improve the imaging performance of Fresnel lens, wavefront aberration of Fresnel lens point-target imaging was experimentally corrected by adaptive optical system without wavefront sensing.The aberration correction control adopted a stochastic parallel gradient descent algorithm The far-field flare like the sharpness function is an optimization index, and the algorithm converges after several iterations.After the system is closed-loop corrected, the equivalent radius of the focal plane flaw is reduced by 43%, the second moment is 0.997 5, close to the ideal limit of 1, Value and peak light intensity doubled, the full width at half maximum of light intensity reached 1.2 times the diffraction limit, and the mid-frequency component of the modulation transfer function increased significantly.The experimental results show that this method has the advantages of simple structure, fast and effective correction of Fresnel lens Wavefront aberration, improve the imaging performance of the system can be applied to large-caliber, lightweight space telescope.