聚焦透镜的像散对光阱力的影响

根据里查德-沃耳夫矢量积分公式,研究了径向偏振光通过具有像散的大数值孔径物镜后在焦点附近的光阱力。着重研究像散对轴向和横向光阱力的影响。研究结果表明,像散的存在导致了光阱力的势垒减弱,光阱中心的偏移,甚至是改变了有效捕捉区域,这将严重影响了光镊的轴向和横向对粒子的捕捉。通过对改变数值孔径的大小和孔径与光腰的比值,以及对不同大小的粒子捕捉效果的对比,可以改变像散对粒子捕捉影响的程度,从而改善像散对光阱力的影响,这对于光镊等精密仪器的操作是十分必要的。

The effect of astigmatism of focusing lens on optical trapping force

Based on Richards-Wolf vectorial diffraction method,the effect of astigmatism of focusing objective on radiation forces of Rayleigh particles is investigated,for the case that a radially polarized beam is focused by a high numerical-aperture system.The influence of astigmatism of focusing objective on the transverse and longitudinal force is mainly concentrated.And the research results show that the change of the astigmatism will influence not only on the magnitude of the radiation forces,but also on the balanced position and the valid area.For the focusing system with different numerical aperture,the ratio of aperture and waist length and particle radius,the degree of astigmatism will also change and this characteristic can be employed to reduce these influences,which is important for the optical trapping and other applications.