针对现有的衍射光学元件设计方法只适用于小角度衍射的情况, 本文提出了一种基于瑞利-索末菲衍射积分的设计方法, 可以用来设计具有大衍射角的衍射光学元件。先对目标光场进行坐标变换和强度调整, 再利用改进的Gerchberg-Saxton算法优化得到衍射光学元件的相位分布。分别采用本文方法和原有的基于夫琅禾费衍射积分的方法设计衍射光学元件实现线条结构光和不同角度方框图形的光场重构, 结果表明: 原有的设计方法只适用于衍射角全角小于25°的情况, 当衍射角大于25°时, 重构光场会出现显著的枕形畸变和不均匀的强度分布。而本文方法在小角度和大角度衍射下都能重构出准确的衍射角和较为均匀的强度分布.

A novel method is presented for designing the diffractive optical element with large diffraction angle based on the Rayleigh-Sommerfeld Integral. In the design, the target intensity distribution is firstly modified with coordinate transformation and intensity adjustment. Thereafter the modified Gerchberg-Saxton algorithm is adopted to optimize the phase distribution of the diffractive optical element. Our method and the original method, which adopts Frauhofer diffraction integral to calculate the diffraction, are used to design the diffractive optical element to reconstruct a structured light and a square pattern with different diffraction angle. And the result shows that the original method can work well only the diffraction angle below 25°. When the diffraction angle gets larger the reconstructed light field shows significant pillow distortion and uneven intensity distribution. In contrast, our method can achieve the exact diffraction angle and even intensity distribution at all the angle.