中文摘要：

通过多项式拟合法计算由于热变形导致的面形改变量，来修正镜面面形系数；然后应用平面对称光学系统的像差理论，计算它对成像的影响。和以往方法不同的是它通过像差形式解析表达，并能得到光线在像面上的点列图分布。如果热变形导致的镜面改变量分布比较复杂，很难用单个面形精确地拟合，建议进行分区拟合以减小拟合误差。最后，通过一个实例，用传统的方法和文中的方法做数值计算比较。

英文摘要：

The polynomial-fit method is used to calculate the deviation of mirror figure due to thermal deformation to modify the coefficients of figure equation of mirror~ its effect on imaging is then calculated with the aberration theory of plan-symmetric grating system. The method is to use the analytical aberration expressions to yield the accurate ray spot diagram while conventionally to use the statistical one to evaluate the figure deviation. If the deformation distribution of mirror is complicated and is difficult to be fitted with a single figure equation accurately, we propose that the fit is performed with multiple areas to reduce the fitting error. Finally, an example is given to model the imaging for a deformed mirror with the conventional and the proposed method in this paper.