Opt Lett. 2013 Dec 15;38(24):5296-8. doi: 10.1364/OL.38.005296.
The first Rayleigh-Sommerfeld diffraction formula is treated in an exact form as a three-dimensional (3D) convolution in the spatial domain. Therefore, a 3D Fourier transform can be employed to convert the 3D diffracted electromagnetic field to the reciprocal space without approximations, which we call the 3D angular spectrum (3D-AS) method. It is also demonstrated that if evanescent waves are neglected, the 3D-AS method can be readily implemented numerically, with the results in good agreement with theoretical predictions.
瑞利-索末菲衍射公式首先被精确地表示为空间域中的三维（3D）卷积。因此，可以采用三维傅里叶变换将三维衍射电磁场转换到倒空间，而无需进行近似，我们称之为三维角谱（3D-AS）方法。还证明，如果忽略消逝波，则可以方便地在数值上实现 3D-AS 方法，并且结果与理论预测非常吻合。
