利用散射矩阵编写的严格耦合波理论，可以用来计算多层光栅结构的光散射情况。其中，金属的介电常数用拟合方法得到。-The use of rigorous coupled-wave theory scattering matrix prepared, can be used to calculate the light scattering multilayer grating structure. Among them, the dielectric constant of the metal is