Aubailly Mathieu, Roggemann Michael C, Schulz Timothy J
Intelligent Optics Laboratory, University of Maryland, 2107 Technology Ventures Building, College Park, Maryland 20740, USA.
Appl Opt. 2007 Aug 20;46(24):6055-63. doi: 10.1364/ao.46.006055.
Atmospheric turbulence corrupts astronomical images formed by ground-based telescopes. Adaptive optics systems allow the effects of turbulence-induced aberrations to be reduced for a narrow field of view corresponding approximately to the isoplanatic angle theta(0). For field angles larger than theta(0), the point spread function (PSF) gradually degrades as the field angle increases. We present a technique to estimate the PSF of an adaptive optics telescope as function of the field angle, and use this information in a space-varying image reconstruction technique. Simulated anisoplanatic intensity images of a star field are reconstructed by means of a block-processing method using the predicted local PSF. Two methods for image recovery are used: matrix inversion with Tikhonov regularization, and the Lucy-Richardson algorithm. Image reconstruction results obtained using the space-varying predicted PSF are compared to space invariant deconvolution results obtained using the on-axis PSF. The anisoplanatic reconstruction technique using the predicted PSF provides a significant improvement of the mean squared error between the reconstructed image and the object compared to the deconvolution performed using the on-axis PSF.
大气湍流会使地基望远镜形成的天文图像失真。自适应光学系统能够针对与等晕角θ(0)大致对应的窄视场，减少湍流引起的像差影响。对于大于θ(0)的视场角，点扩散函数（PSF）会随着视场角的增大而逐渐退化。我们提出一种技术，用于估计自适应光学望远镜的PSF随视场角的变化，并将此信息应用于空间变化图像重建技术中。利用预测的局部PSF，通过块处理方法重建星场的模拟非等晕强度图像。使用了两种图像恢复方法：带蒂霍诺夫正则化的矩阵求逆法和露西 - 理查森算法。将使用空间变化预测PSF获得的图像重建结果与使用轴上PSF获得的空间不变解卷积结果进行比较。与使用轴上PSF进行的解卷积相比，使用预测PSF的非等晕重建技术显著降低了重建图像与目标之间的均方误差。
