Optimal wave-front reconstruction strategies for multiconjugate adaptive optics.
Optimal wave-front reconstruction strategies for multiconjugate adaptive optics.
复制标题
多重共轭自适应光学的最佳波前重建策略。
DOI：
--
复制
发表时间：
2001
影响因子：
1.9
通讯作者：
V. Michau
中科院分区：
文献类型：
--
作者：
T. Fusco;J. Conan;Gérard Rousset;L. Mugnier;V. Michau
提出了一种多共轭自适应光学大视场相位重构的优化方法。这种最佳方法是基于最小均方误差估计，最小化的平均剩余相位方差在感兴趣的FOV。它考虑了C2n轮廓，以便最佳地估计要应用于每个可变形反射镜（DM）的校正波前。由于C2n剖面是高度h的连续函数，因此这种最佳方法还考虑了DM的数量总是小于湍流层的数量这一事实。建立了这种最佳方法和湍流体积的层析重建之间的联系。特别是，它表明，最佳的方法包括一个完整的层析重建的湍流体积，然后由一个投影到DM占所考虑的FOV的兴趣。湍流层的情况下，假设匹配的镜像位置[模型近似（MA）的方法]，这可能是一个粗略的近似，也被认为是比较。这种MA方法将依赖于等效湍流层的概念。最佳和MA方法之间的比较。结果表明，最佳的方法提供了非常好的性能，即使有少量的DM（通常是一个或两个）。例如，一个4米望远镜在150弧秒× 150弧秒的视场上，只使用三颗导航星和两颗DM，就可以获得良好的斯特列尔比（大于20%）。
We propose an optimal approach for the phase reconstruction in a large field of view (FOV) for multiconjugate adaptive optics. This optimal approach is based on a minimum-mean-square-error estimator that minimizes the mean residual phase variance in the FOV of interest. It accounts for the C2n profile in order to optimally estimate the correction wave front to be applied to each deformable mirror (DM). This optimal approach also accounts for the fact that the number of DMs will always be smaller than the number of turbulent layers, since the C2n profile is a continuous function of the altitude h. Links between this optimal approach and a tomographic reconstruction of the turbulence volume are established. In particular, it is shown that the optimal approach consists of a full tomographic reconstruction of the turbulence volume followed by a projection onto the DMs accounting for the considered FOV of interest. The case where the turbulent layers are assumed to match the mirror positions [model-approximation (MA) approach], which might be a crude approximation, is also considered for comparison. This MA approach will rely on the notion of equivalent turbulent layers. A comparison between the optimal and MA approaches is proposed. It is shown that the optimal approach provides very good performance even with a small number of DMs (typically, one or two). For instance, good Strehl ratios (greater than 20%) are obtained for a 4-m telescope on a 150-arc sec x 150-arc sec FOV by using only three guide stars and two DMs.