High-resolution imaging in the visible from the ground without adaptive optics: new techniques and results
High-resolution imaging in the visible from the ground without adaptive optics: new techniques and results
复制标题
无需自适应光学器件即可从地面进行可见光高分辨率成像：新技术和结果
DOI：
10.1117/12.550443
复制
发表时间：
2004
影响因子：
2.3
通讯作者：
P. Warner
中科院分区：
文献类型：
--
作者：
C. Mackay;J. Baldwin;N. Law;P. Warner
许多天文成像研究，例如弱引力透镜的研究，要求比通常从地面在宽视场上可能获得的更好的角分辨率。对于许多此类研究，天文学家需要图像在整个视场上显示一致的点扩散函数，即使这是以牺牲视场中心的最终角分辨率为代价的。自适应光学并没有显示出能够实现可见波长所需的大视场的前景，因此必须开发一种从地面传输高分辨率图像的新技术。电子倍增 CCD 可以高速拍摄图像，而不会出现通常的读取噪声问题。我们开发了一种称为“幸运成像”的新技术，该技术通过从图像序列中选择更好的图像，然后移动并添加每个图像以提供更高分辨率的输出图像来实现高分辨率。在相对良好的条件下，使用工作在 I 波段（850 纳米）的 2.5 米望远镜并使用多达 30% 的拍摄图像，通常可以获得 0.1-0.2 角秒范围内的分辨率。即使在较差的条件下，我们发现图像选择也可以使最终分辨率比传统视宁值好三倍之多。本文介绍了该技术以及使用该方法获得的一些结果。
Many astronomical imaging studies, such as those of weak gravitational lensing, call for better angular resolution than is normally possible from the ground over wide fields of view . For many of these studies astronomers need images which show a consistent point spread function across the field even if this comes at the expense of the ultimate in angular resolution at the centre of the field. Adaptive Optics does not show any prospect of being able to achieve fields of view as large as are needed at visible wavelengths and therefore a new technique of delivering high resolution images from the ground must be developed. Electron multiplying CCDs are available that allow images to be taken at high speed without the usual penalty of read noise. We have developed a new technique called Lucky Imaging which achieves high resolution by selecting the better images from a sequence of images, then shifting and adding each to give a much higher resolution output image. Resolutions in the range 0.1-0.2 arc seconds can be obtained routinely under relatively good conditions on a 2.5 metre telescope working in I band (850 nanometres) and using as much as 30% of the images taken. Even under poorer conditions we find that image selection allows the final resolution to be better than the traditional seeing value by a factor of as much as three. This paper describes the technique and some of the results obtained using this method.