从理论和实验上探讨了体光栅在垂直方向的角度选择性，根据ｋ矢量球与参考点源平面上的对应关系，导出了垂直方向的选择角，并得到光栅简并线方程。实验结果表明体光栅在垂直方向具有有限的选择角 The angle selectivity of the volume grating in the vertical direction is discussed theoretically and experimentally. According to the correspondence between the k-vector sphere and the reference point source plane, the selection angle in the vertical direction is derived and the grating degeneracy equation is obtained. The experimental results show that the volume grating has a limited choice angle in the vertical direction