Research On Active Control Of The Segmented Telescope Based On Tip Detection

The 8m ring segmented telescope is an important candidate solution for the Chinese Giant Telescope project.In active control,because of the particularity of ring segmented telescope,it is necessary to add high precision tip detection to realize closed-loop control of active optics.Optical measurement method has the potential of high precision detection,but optical detection is very sensitive to the environment.The wavefront distortion caused by atmospheric turbulence is the most important error source of optical tip detection.Therefore,the influence of atmospheric turbulence disturbance on the accuracy of tilt detection is studied by numerical simulation,and the theoretical detection accuracy in the presence of atmospheric turbulence is given.In order to realize the closed-loop control of active optics,a Shack-Hartmann wavefront detector is constructed for real-time detection of segments tip based on the edge detection of segments in the experiment of ring segmented telescope active optics,which focuses on the key technology of 8m RST active optics.Therefore,the Shack-Hartmann tip measurement system of the edge of the segments is calibrated by using the PhaseCam@6000 interferometer and the edge sensor installed on sub-segment,and its measurement accuracy is evaluated quantitatively.On this basis,we measure and calibrate the active control model of the segmented mirror experimental system including edge sensor and tip sensor.Finally,we realize the closed-loop experiment of active control of the segmented mirror by combining the edge detection of the sub-segment with tip detection of the sub-segment.We also analyze the influence of different sampling frequencies on the experimental results of active closed-loop control.This study provides a reference for the development and implementation of 8m RST high precision tip measurement technology and closed-loop control technology.