In order to solve the error of interference matrix in the design of multiplayer mirrors for soft X-ray, a multinomial theory is presented in this paper and it is applied in the designing of the multiplayer mirrors at the wavelength of 13.4nm and 11.2nm.

• 针对软X射线波段多层膜反射镜设计中干涉矩阵的计算误差问题；提出了采用切比雪夫多项式的理论对干涉矩阵进行了分析与计算的方法.；并使用该方法对软X射线中波长为13