余弦平方高斯光束通过无光栏透镜的梯度力

Gradient force pattern of cosine-squared Gaussian beams through lens without aperture

基于Collins公式推导了余弦平方高斯光束通过无光栏透镜光学系统聚焦后的光强分布及梯度力,采用数值模拟分析梯度力分布及光阱的数量、位置及尺度随光束参数、光束入射距离及系统菲涅耳数的变化。结果表明:光束相关参数b越大光阱的数量越多,光阱的位置随光束入射距离而改变,大小随系统菲涅耳数的增加而减小,但不影响其位置。

The intensity distribution and gradient force pattern of cosine-squared Gaussian beams focused by a thin lens without aperture were derived based on the Collins formula. Through the numerical simulation, the influence of the beams parameter, relative incident sep- aration and beams Fresnel number on the distribution of gradient force pattern, the number, position and size of the optical traps were discussed. The results indicated that the bigger the beams parameter b, the more the optical traps~ the position of optical trap changed with the beams relative incident separation, and the size decreased with the increase of Fresnel number of the system while the position stayed unchanged.