宽视场望远镜大气非等晕性的数值分析

Numerical Analysis of Anisoplanatism of Wide-field-of-view Telescope Imaging through Turbulent Atmosphere

为了减少非等晕性对望远成像系统性能的影响,扩大系统的有效视场,对宽视场望远成像系统的非等晕性进行了研究。首先采用多层相位屏法实现了非等晕成像的数值模拟,然后利用数值模拟系统计算了典型大气条件下(大气相干长度r0=0.1m)轴中心点与偏离轴θ角度目标点两者间的畸变波前均方差值,分析了系统口径D分别为1m、2m和4m对应畸变波前均方差值随偏离角度θ的变化情况。分析结果表明,畸变波前有倾斜项时,系统口径D越大,畸变波前均方差值随角度θ的增加上升得越慢,非等晕性的影响越小;去掉倾斜畸变时,系统口径D越大,畸变波前均方差值随角度θ的增加上升得越快,非等晕性的影响越严重。倾斜非等晕性随系统口径的增加而减少,对大口径的望远成像系统(D≥5m)主要考虑高阶波前畸变对成像的影响。

In order to reduce the influence of anisoplanatism on the performance of telescope imaging system,and expand the effective Field-of-view（FOV） of system,anisoplanatic effect in wide-field-of-view telescope imaging system is studied here.First,a numerical simulation of anisoplanatic imaging through volume atmospheric turbulence by using multiple random phase screens has been developed.Then,the mean-square wave front errors of two separate object points between the on-axis position and the off-axis position with angle θ are calculated based on the numerical simulation system under the typical atmospheric condition（atmospheric coherent length r0 = 0.1 m）.The results show that when tilt errors have been included in the aberrated wave front,anisoplanatic effect becomes weaker as the diameter D of the imaging system increases,and the ascending variation of the mean-square wave front errors is less severe.Whereas,when tilt errors have been excluded,anisoplanatic effect becomes greater as the D increases,and the ascending variation of these is more severe.The larger the diameter of system aperture is,the weaker tilt anisoplanatism is.For large-aperture telescope imaging system,like D≥5 m,high-order wave front errors are the crucial influence.