Research in Astronomy and Astrophysics First Generation Solar Adaptive Optics for 1-m New Vacuum Solar Telescope at Fuxian Solar Observatory ∗

Abstract The first generation solar adaptive optics (AO) system, which consists of a fine tracking loop with a tip-tilt mirror (TTM) and a correlation tracker, and a high-order correction loop with a 37-element deformable mirror (DM), a correlating Shack-Hartmann (SH) wavefront sensor (WFS) based on the Absolute Difference algorithm and a real time controller (RTC), had been developed and installed at the 1-m New Vacuum Solar Telescope (NVST) of the Fuxian Solar Observatory (FSO). Compared with the 37-element solar AO system developed for the 26-cm Solar Fine Structure Telescope of Yunnan Astronomical Observatory in 2009, this AO system has two updates: one is the subaperture arrangement of the WFS changed from square to hexagon; the other is the high speed camera of the WFS and the corresponding real time controller. The WFS can be operated at the frame rate with 2100 Hz and the error correction bandwidth can exceed 100 Hz. After AO correction, the averaged residual image motion and the averaged RMS wavefront error are reduced to 0.06 arcsec and 45 nm, respectively. The results of on-sky testing observation demonstrate better contrast and finer structures of the images with AO than those without AO. Key words: solar adaptive optics; correlation tracker; correlating Shack-Hartmann wave-front sensor; active region.