以轴对称光学系统的初级矢量波像差理论为基础, 通过引入孔径缩放因子和孔径偏移矢量, 获得了离轴反射光学系统初级像差特性。通过分析可知: 离轴反射光学系统的初级像差依然由球差、彗差、像散组成。由于孔径缩放因子存在, 离轴反射光学系统的波像差系数均有不同比例的减小, 且轴对称光学系统的高级孔径像差会在对应离轴光学系统中引入较低阶孔径像差, 例如轴对称光学系统未校正球差, 对应的离轴光学系统除过球差外还将引入彗差、像散等。相比于轴对称光学系统的像差, 由于孔径偏移矢量的引入, 离轴反射光学系统的像差不再关于中心视场旋转对称, 有可能在轴外视场产生像差零点。

Based on the 3rd vector wavefront aberration theory of axial symmetry optical system, the vector aberration expansions of off-axis optical system was obtained by pupil zoomed factorial and pupil decenter vector in this paper, . It is known through the analysis that the off-axis optical system′s aberration are still composed of 3rd spherical aberration 3rd coma and 3rd astigmatism. Due to the impact of pupil zoomed factorial, the decrease of the off-axis optical system′s aberration coefficients were different proportion. The higher-order pupil aberration of coaxial system will induce low-order pupil aberration into off-axis mirror system. For example, if the coaxial system is not corrected for 3rd spherical aberration, it will introduce not only the spherical but also the constant coma and astigmatism into off-axis system. The aberration of off-axis system will not be asymmetry by the field center because the induced low-order aberration, and there maybe have an aberration zero point outside the center field of the view.