为了评价光栅的光谱质量，完成所设计光栅的光线追迹，针对机械刻划光栅的光线追迹提出了一种改进方法。在费马原理的基础上利用光程函数法得到入射光通过光栅后的光谱分布情况，再使用传输矩阵的计算方法构造出光谱的点列图。该方法适用于刻划在平面、球面和非球面基坯上的等间距和变间距光栅，光栅的光谱面可以为平面或者二次曲面。 通过刻划在非球面基坯上的凹面光栅验证了光线追迹方法的可靠性。

To evaluate the quality of grating, it is desirable to have a ray tracing map of the designed grating. A method of ray tracing for mechanically ruled gratings is developed. Based on Fermat’s principle and light path function, it gets the spectral distribution of the incident rays, and it can get the ray tracing map through a matrix method. The method is applicable to plane, spherical and aspheric gratings with variable spacing. The groove spacing can vary in arbitrary forms, and the image surface can be chosen as a plane or a conicoid. The ray tracing map of a concave grating ruled on toroidal surface proves the feasibility of the method.