两束不同偏振态的光入射到由两个透镜组成的聚焦系统，利用Richard-Wolf 矢量衍射理论计算系统的衍射场分布，分析了数值孔径(NA)较小时系统对Rayleigh 粒子的俘获特性。金粒子的折射率大于周围介质(nm)，空气泡的折射率小于周围介质。NA=0.58 nm 时，光轴上产生明暗相间的光斑阵列，可以用来同时俘获多个亚波长大小的金粒子和空气泡。NA=0.35 nm时，沿着光轴产生波长大小的圆环阵列，可2D 俘获多个空气泡。

Two beams of light with different polarizations are incident on a focusing system with two lenses. Based on Richard-Wolf vectorial diffraction theory, the diffraction field distribution is calculated. Properties of optical trapping using the focusing system are analyzed when numerical aperture (NA) of lenses is low. A gold particle′s refractive index is higher than that of the medium (nm), and an air bubble′s is lower. When NA=0.58 nm, subwavelength bright and dark spot array is generated on the optical axis. These spots can be used to trap multiple gold particles and air bubbles. When NA=0.35 nm, wavelength cylindrical rings are formed around the optical axis, which can be used to two-dimensionally trap multiple air bubbles.