本文基于光栅方程矢量化，将传统二维平面光栅衍射的二维作用域延拓至三维空间，并定量分析了三维欧式空间中入射光经光盘衍射后方向具有可预测性.本文通过将光栅方程矢量化，定量解释了在远距条件下光盘表面彩色线状结构出现的必然.引进空间光锥对衍射主极大的上确界进行了定量计算，并将衍射光方向进行了很好的可视化描述.最后结合色散本领、重叠现象、深阱效应和视差角，较好地解决了如何经光盘衍射后得到更纯的彩色线，并给出了CD和DVD两种常见光盘的共性和差异性，发现理论和实验符合较好.

Based on the vectorization of grating equation, two-dimensional scope of grating diffraction is extended to three-dimensional space. The predictability of direction of incident light diffracted by optical disc in three-dimensional Euclidean space is quantitatively given. The grating vector is introduced to quantitatively explain the necessity of color line-line structure on the surface of optical disc under the condition of long distance. The spatial light cone is introduced to quantitatively calculate the principal maximum supremum of diffraction, which has a good visualization effect. Combining the dispersion power, overlap phenomenon, deep well effect and parallax angle, in this paper the problem of how to diffract more pure color lines by optical discs is solved, the commonness and difference between CD and DVD is given, and the theory is found to consistent with the experiment result.