基于Richards-Wolf的矢量衍射积分公式,研究了贝塞尔高斯径 向偏振光束在衍射光学元件 (Diffractive optical elements, DOE) 的调制下入射到由 两个相同高数值孔径透镜组成的4pi聚焦光学系统中的聚焦特性。由于DOE不同环之间的相互干涉, 出现不同于原贝塞尔高斯径向偏振矢量光束的新聚焦特性。Matlab数值模拟结果显示贝塞尔高斯径向偏 振光束经过此光学系统后,在焦点附近产生沿光传播方向的多个光球,其光球的个数与DOE的环数以及不 同环的大小有关。若调节4pi聚焦系统两侧入射光束的整体相对相位还可以实现多个光球整体沿纵向方向的移动, 实现了亮光链的作用,这对于矢量光束应用在光学显微镜、光存储和粒子操控等方面具有十分重要的意义。

By using the Richards-Wolf vector diffraction theory, the focusing properties of Bessel-Gaussian radially polarized laser beams modulated with a diffractive optical element (DOE) in a 4pi focusing system were investigated which consists of two same high numerical aperture lens. Due to the adjacent ring interference of DOE, the intensity distribution near the focus is different from the intensity distribution without DOE modulation. The results simulated by Matlab show that the multifocal spherical spots can be obtained when Bessel-Gaussian radially polarized beam passes through this optical system. The number of spherical spots is associated with the number of belts of DOE and relative size of adjacent ring. The spherical focal spots can move along the optical axis if the relative phase of left and right of the incident beam is changed. The results show important applications in optical microscopy, optical data storage, and particle manipulations.