用振幅矢量作图法研究二元位相元件各级衍射光强的分布规律.并得出了普遍的衍射效率公式，方法简便，物理图像清晰，结果普遍适用。

In this paper, we have studied the all difftaction orders intensity distribution lawin a binary optical element by phasor addition and have gotten a diffraction efficiencyformula. The method is simple and the physica] picture is clear. The result may be helpfulfor well understanding diffraction intensity changes in optical elements of binary structure.