STUDIES ON HIGH-RESOLUTION IMAGING WITH TWO-COLOR SPECKLEGRAMS

从地面观察到的恒星物体的短曝光图像显示出斑状图案，因为地球的大气湍流。然而，这样的散斑图包含了望远镜衍射极限分辨率下物体的信息。散斑干涉法是除自适应光学外获得高分辨率图像的一种简便方法。当两个波长差异很大的散斑图之间存在高度相关性时，参考另一个波长的散斑图，在一个波长上实现高分辨率成像是可行的，其中恒星物体作为点源或参考星出现。本课题的研究目的是通过对两种不同波长的散斑图进行分析，建立双色散斑图的高分辨率成像方法。我们用连接在冈山天体物理天文台90厘米或188厘米望远镜上的双色斑点相机对卡佩拉和织女星进行了观测。检测波长短为400nm或450nm，长为800nm。这些波长对应于可见区域的极端，比例约为2。对一个波长的散斑图进行移位加运算，结果是在另一个波长上产生伴随的重建图像。结果表明，参考另一波长的散斑图重建的一个波长的图像比通过对散斑图定心并增加其重力产生的伪长曝光图像效果更好。这表明，高分辨率成像是可能的利用散斑图在不同的波长。我们的方法在可见光-近红外观测中的应用仍然是一个未来的项目。

A short exposure image of a stellar object observed from the ground exhibits a speckle-like pattern because of atmospheric turbulence of the earth. However, such a specklegram contains the information of the object with diffraction-limited resolution of a telescope. The speckle interferometry is a simple method to get high-resolution image apart from adaptive optics. When there is a high correlation between two specklegrams with greatly differnt wavelengths, high-resolution imaging is feasible at one wavelength by reference to a specklegram at the other wavelength where the stellar object appears as a point-source or a reference star is available.The purpose of this research project is to establish high-resolution imaging method with two-color specklegrams by analysing specklegrams at two greatly different wavelengths. We conducted observations of Capella and Vega with our two-color speckle camera attached to the 90cm or 188cm telescope at the Okayama Astrophysical Observatory, NAOJ.The detection wavelengths are 400nm or 450nm at the short wavelength and 800nm at the long one. These wavelengths correspond to the extremes of the visible region and the ratio is about two.The shift-and-add operation for specklegrams at one wavelength results in an accompaningly reconstructed image at the other wavelength. It is clarified that the reconstructed image at one wavelength by reference to specklegrams at the other wavelength is better than the pseudo long exposure image, which is produced by centering and adding the gravity of specklegrams. This shows that high-resolution imaging is possible by utilizing specklegrams at the different wavelength. The application of our method to visible-NIR observations remains as a future project.