基于夏克-哈特曼传感器的星载望远镜波前测量技术研究

Research on wavefront measurement technologyof space-based telescope using Shack-Hartmannwavefront sensor

精确的测量和控制星载望远镜的波前像差是实现高效空间引力波探测的关键。本文提出了一种基于夏克-哈特曼波前传感器原理的星载望远镜波前像差测量方法,该方法采用经过频域阈值去噪处理后的频域上的互相关算法,使用子孔径数20×16、微透镜尺寸0.279 mm×0.279 mm、焦距34 mm的夏克-哈特曼波前传感器对算法的测量精确度进行验证。对实际点源图像生成已知RMS离焦值(0, 0.22, 0.44, 0.66 nm),从而产生具有偏移量的点源图像。使用模式法进行波前复原后,计算复原波面和残余波面的RMS值,用于比较频域上的互相关算法和传统质心算法的测量精度。结果显示,随着实际离焦值的增加,质心算法的测量误差呈现上升趋势,分别为0.0966 nm, 0.1378 nm,0.1284 nm和0.1463 nm。频域互相关算法可以使夏克-哈特曼波前像差均方根(RMS)误差分别减少13%, 7%, 18%和14%,为空间引力波星载望远镜地面波前像差的高精度测试提供了重要参考。

Accurate measurement and control of wavefront aberrations in space-based telescopes are key to achieving efficient space gravitational wave detection.This paper presents a method for measuring wavefront aberrations of space-based telescopes based on the Shack-Hartmann wavefront sensor.This method employs a cross-correlation algorithm in the frequency domain after frequency domain threshold denoising.The measurement accuracy of the algorithm is verified using a Shack-Hartmann wavefront sensor with 20×16 sub-apertures,microlens dimensions of 0.279 mm×0.279 mm,and a focal length of 34 mm.Point source images with known defocus RMS values(0,0.22,0.44,and 0.66 nm)are generated,producing point source images with displacements.After wavefront reconstruction using the modal method,the RMS values of the reconstructed and residual wavefronts are calculated,comparing the measurement accuracy of the cross-correlation algorithm in the frequency domain with the traditional centroid algorithm.The results show that as the actual defocus value increases,the measurement error of the centroid algorithm presents an upward trend,respectively at 0.0966 nm,0.1378 nm,0.1284 nm,and 0.1463 nm.The cross-correlation algorithm in the frequency domain can increase the measurement accuracy by 13%,7%,18%,and 14%respectively,providing an important reference for the highprecision testing of wavefront aberrations of space gravitational wave space-based telescopes on the ground.