拼接式望远镜子镜间平移、倾斜误差及子镜间隙对成像质量的影响

Effects of Piston, Tip-tilt and Gap Errors on Image Quality of the Segmented Telescope

通过理论及数值仿真分析拼接式望远镜中子镜的平移误差、倾斜误差和子镜间隙对系统成像质量的影响。理论推导了存在不同误差时拼接式望远镜点扩散函数(PSF)及远场光斑斯特列尔比(S.R,用RS.R表示)的表达式,建立了三种误差对拼接式望远镜PSF和远场光斑RS.R的影响的仿真模型,分析了三种误差分别对拼接式望远镜成像质量的影响。分析结果表明:当子镜存在平移误差时,拼接式望远镜成像质量随着子镜平移误差标准差δ增加逐渐变差,当δ<λ/20时,拼接式望远镜远场光斑RS.R>0.9;当子镜存在倾斜误时,拼接式望远镜成像质量随着波前相位均方差(RMS,用erms表示)增加逐渐变差,当erms<0.3 rad时,拼接式望远镜远场光斑RS.R>0.9;当子镜间存在间隙时,拼接式望远镜成像质量随着间隙因子w增大逐渐变差,当w<0.025时,拼接望远镜远场光斑RS.R>0.9。

The impact of segmented telescope piston error, tip-tilt error and gap on image quality by theoretical and numerical simulation was analyzed. Different error segmented telescope Point-spread-function （PSF） and the far-field spot Strehl Ratio （S.R） expression were derived theoretically. Then, set up simulation model about three kinds of error effect on segmented telescope PSF and far-field spot S.R, and analyzed three kinds of error influence on imaging quality of splicing telescope. Analysis results show that：when the segmented mirror exist piston error, segmented telescope image quality with piston error standard deviationδincreasing gradually becomes poor;whenδ〈λ/20 segmented telescope, the far field spot RS.R〉0.9;when the segmented mirror exist tip-tilt error, the segmented telescope imaging quality with the wavefront phase RMS increases gradually worse, when eRMS〈0.3 rad, the far-field spot of the segmented telescope RS.R〉0.9; when the segmented mirror exist gap, its imaging quality with the gap factor w increases gradually becomes poor, and when w〈0.025, a segmented telescope far-field spot RS.R〉0.9.