On super-resolution in astronomical imaging
On super-resolution in astronomical imaging
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DOI：
10.1051/0004-6361:20042320
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发表时间：
2005-06-01
影响因子：
6.5
通讯作者：
Kneer, F
中科院分区：
文献类型：
--
作者：
Puschmann, KG;Kneer, F
我们的工作是试图实现天文成像的目标之一，即获得高角分辨率的信息。作为点源的恒星可以用狄拉克δ函数表示，其傅里叶变换包含了所有角频率下的位置和（积分）强度信息。因此，我们可以去卷积的星星领域，即使在角距离小于衍射极限的望远镜进行观测的未解决的图像。我们给出了一个例子，重建的图像的两颗恒星的角间距的一个因素2.5小于α（Ra）= 1.22 × lambda/D。然而，我们发现，超分辨率是可行的，只有点源。对于扩展对象，关于角频率u > u（max）= D/lambda = 1/alpha（min）处的强度波动的信息不可挽回地丢失了。我们讨论了不可能的超分辨率的太阳使用数值模拟图像的太阳颗粒。然而，人们可以增强太阳图像的对比度，尽管没有增加超过衍射极限的角分辨率。
Our work is an attempt to fulfil one of the aims of astronomical imaging, that is, to obtain information at high angular resolution. Stars as point sources can be represented by Dirac delta-functions whose Fourier transforms contain information about the position and the (integrated) intensity at all angular frequencies. Thus, we can deconvolve unresolved images of star fields even at angular distances smaller than the diffraction limit of the telescope with which the observations are performed. We give an example of reconstruction of the image of two stars with an angular separation of a factor 2.5 less than alpha(Ra) = 1.22 x lambda/D. However, we find that super-resolution is feasible only for point sources. For extended objects the information about intensity fluctuations at angular frequencies u > u(max) = D/lambda = 1/alpha(min) is irretrievably lost. We discuss the impossibility of super-resolution for the Sun using a numerically simulated image of solar granulation. However, one can enhance the contrast of solar images, though without increasing angular resolution beyond the diffraction limit.