基于无波前传感的菲涅耳透镜像差校正实验

Experiments of the Aberrations Correction for Membrane Fresnel Lens Based on Wavefront Sensorless

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.

To improve the imaging quality of Fresnel lens,a wavefront sensorless adative optics system is used to compensate the wavefront aberrations in Fresnel lens imaging system for point source.During the aberrations correction,the stochastic parallel gradient descent algorithm is adopted to optimize the image clarity evaluation function,which is converged after dozens of correction iterations.The performance of Fresnel Lens imaging system is improved notably by adaptive optics,that the efficient radius of far-field is reduced by 43%,the corresponding second moment is 0.9975 near to the theoretical limit value 1,the image clarity and the peak value of intensity are enhanced more than once,the corresponding FWHM is upto 1.2 DL,and more sufficient medium frequncies are raised up in Modulation Transfer Function（MTF）.The results demonstrate that the aberrations in Fresnel lens imaging system for point source is fastly and effectively compensated by the wavefront sensorless adative optics system,which is can be applied to the space telescope due to its simple implementation structure.