The Progress in Speckle-Imaging Experiment with the 1.56m Telescope of the Shanghai Astronomical Observatory

The speckle-imaging technique is one of effective methods that can largely compensate atmospheric turbulence effects to improve the resolution of a ground-based telescope. The technique utilizes a speckle camera to obtain a series of short-exposure images where the turbulence effects are almost instantaneous, and then reconstruct a high-resolution image by image processing. For its convenient implementation, this technique has been widely used in observational astronomy, especially for observing binary stars. This paper first briefly reviews the development of astronomical high-resolution image reconstruction techniques, by describing research achievements, some typical methods, and the disadvantages of these methods. The paper subsequently describes the type of noise in speckle images and filtering methods. We experiment the technique by observing binary stars with the 1.56m telescope. The object magnitudes are between 4 and 7, and the magnitude differences in the binary systems are less than 2. The high-resolution images of binary stars are reconstructed successfully with the speckle interferometry and the Iterative Shift-and-Add method. It is shown that the speckle-imaging experiment on the 1.56m telescope has reached the diffraction-limit resolution of the telescope.