强大气湍流下扩展信标波前重建方法研究

Wavefront reconstruction for extended beacons under strong atmospheric turbulence

针对强湍流环境下自适应光学系统无理想点信标波前探测的难题,本文提出利用光场传感器(Plenoptic sensor)对扩展信标进行光场信息探测。对扩展信标的光场成像原理、波前位相重建算法、误差影响规律进行研究,利用等效法将扩展信标看做数个离散点的集合,简化扩展信标在光场传感器上的成像过程,然后将光场图像按照特定方式重新进行排列组合。通过图像互相关法和Zernike模式法实现0°视场的波前重建。针对不同输入像差系数、单列微透镜单元数和噪声等误差影响因素进行仿真研究,结果表明:当输入像差在6.5λ以内时,波前重建精度约为0.08λ,对于图像分辨率为1080×1080、像元尺寸为5.5μm的图像探测器,单列微透镜单元数在40~50之间时波前重建精度最高,此外,系统噪声几乎不影响精度。最后,搭建了扩展信标波前探测系统,通过探测扩展信标对0°视场的4种像差波前进行重建,实验系统的波前重建精度约为0.04λ,基本满足自适应光学系统的波前检测要求。

Aiming at the wavefront detection without an ideal point beacon in the adaptive optical system under the strong turbulent environment,we proposed a method to detect the optical field information of extended beacons using a Plenoptic sensor.The optical field imaging principle,wavefront phase reconstruction algorithm,and error influence rule of extended beacons were studied.The imaging process of the extended beacon on the optical field sensor was simplified through the equivalence method,and the optical field images were rearranged in a specific way.The image cross-correlation and Zernike mode methods were used to realize the wavefront reconstruction of the 0°field of view.Simulation studies were conducted on error-influencing factors such as different input aberration coefficients,the number of single-row microlens elements,and noise.The results show that when the input aberration is less than 6.5λ,the wavefront reconstruction accuracy is about 0.08λ.For the image detector with an image resolution of 1080×1080 and pixel size of 5.5μm,the wavefront reconstruction accuracy is the highest when the number of single row microlens units is between 40 and 50,and the system noise hardly affects the accuracy.Finally,an extended beacon wavefront detection system was built to reconstruct the four aberrant wavefronts of 0°field of view by detecting the extended beacon.The wavefront reconstruction accuracy of the experimental system is about 0.04λ,which meets the wavefront detection requirements of the adaptive optical system.