初级球差及孔径对径向偏振高阶矢量贝塞尔-高斯光束聚焦的影响

The Effect of Primary Spherical Aberration and Aperture on Focusing of Radially Polarized High-Order Vector Bessel-Gauss Beams

在束腰不在物镜入瞳位置的一般情况下,利用理查德-沃尔夫矢量衍射积分公式获得了径向偏振高阶矢量贝塞尔-高斯光束通过有初级球差和受孔径限制的物镜聚焦的三维光场的径向,方位角和纵向分量表达式。数值模拟了入射光束受圆孔径和环形孔径限制情况下初级球差对光场分布的影响。结果表明:球差对焦平面光场分布的影响是非常小的,尤其是环形孔径限制情况下球差的影响可以完全忽略;在受圆形孔径限制情况下,光束经有球差物镜聚焦后,焦平面前后的光场分布不再对称。球差导致在焦平面各点的强度分布变化并不总是一致变大,或一致变小;使用环形孔径时光束聚焦后的光斑尺寸要远小于使用圆形孔径时光束聚焦后的光斑尺寸。

Using Richard-Wolf vector diffraction integral formulae,the radial,azimuthal and longitudinal component expressions of the focused three-dimensional light field of radially polarized high-order vector Bessel-Gauss beams by an objective with primary spherical aberration and obstructed by an aperture are obtained. The effects of primary spherical aberration on the focused light field distribution by the objective obstructed with a circular aperture and an annular aperture are numerically simulated. It is shown that, the influence of spherical aberration on the light distribution at the focal plane is very small especially for the case of the objective obstructed with an annular aperture. In the case of an objective with spherical aberration and obstructed with a circular aperture, the focused light fields before and after the focal plane are not symmetrical. The intensity-distribution change of each point at the focal plane resulted by spherical aberration does not uniformly increase or decrease. The size of the light spot at the focal plane focused by an objective obstructed with an annular aperture is much smaller than the one focused by an objective obstructed with a circular aperture.