Noise analysis in wavefront sensor subaperture optimization

An adaptive optics system with the adaptive ability to different detected objects and seeing conditions is being investigated in Beijing Institute of Technology. When seeing conditions are good, and the Shack-Hartmann wave front sensor of adaptive optics system is working under very low light level, the subaperture of Shack-Hartmann sensor need to be adjusted larger than that when it is working under higher light level and the seeing condition is not good enough. By setting a motorized zoom lens in front of the Shack-Hartmann WFS of a conventional adaptive optics system, the subaperture array of the WFS can be adjusted from 8 X 8 to 2 X 2 in the pupil of the telescope with step by step if necessary. With this method, the overall performance of adaptive optics system can be boosted. Based on an adaptive optics system of the 1.2 meter telescope, a discussion on the noise analysis of Shack-Hartmann WFS associated with subaperture optimization is presented in this paper.