基于矢量衍射理论,计算了径向偏振光束在焦点处光强分布。在径向偏振光束的聚焦过程中,焦斑大小主要取决于视场边缘的光线。根据这一特点,设计了以视场角正切值为自变量的连续型相位滤波函数。利用非线性规化算法,以缩小焦平面上横向宽度为目标,在不同的斯特尔比的约束条件下,优化得到一组相位滤波参数。计算结果表明,径向偏振光束通过此种相位滤波器再聚焦后,在保持相同斯特尔比的条件下,可获得更小的聚焦光斑。 Based on the vector diffraction theory, the intensity distribution of the radially polarized beam at the focal point was calculated. During the focusing of a radially polarized beam, the focal spot size depends mainly on the light at the edge of the field of view. According to this feature, a continuous phase filter function is designed with the angle of view tangent as an independent variable. By using non-linear regularization algorithm, aiming at reducing the lateral width of the focal plane, a set of phase filtering parameters are optimized under different constraints of the Sturgeon. The results show that the radial polarized beam refracted by this kind of phase filter can obtain smaller focal spot under the condition of maintaining the same Stellar ratio.