LIU Dongmei^1,2,WANG Tongxu^1a,CHEN Ya^1a,WEN Yanrou^1a,WEN Hanze^1a,HAN Peng^1,2

(1a.School of Physics and Telecommunication Engineering;1b.Guangdong Provincial Engineering Research Center for Optoelectronic Instrument,South China Normal University,Guangzhou 510006,China;2.SCNU Qingyuan Institute of Science and Technology Innovation,Qingyuan 511517,China)

Abstract:A Bessel-Gaussian beam was generated by a ring-shaped phase optical diffraction structure and projected into a solution of polystyrene spheres undergoing Brownian motion.Based on coaxial differential dynamic microscopy,the diffusion coefficients of polystyrene beads with a particle size of 813 nm under different optical powers were measured.The influence of the Bessel-Gaussian beam on the diffusion motion of the ball was studied and compared with that of the ball under the action of the Gaussian beam.The results show that the diffusion coefficients of the restricted Brownian motion of polystyrene spheres are smaller than those of without laser action,whether under the action of Gaussian beam or Bessel-Gaussian beam.Under the same laser power,the diffusion coefficients of the balls under the action of Bessel-Gaussian beams are all larger than those under the action of Gaussian beams.With the increase of laser power,the diffusion coefficients of the spheres under the irradiations of the two beams first decrease and then increase slightly.

Keywords:diffusion coefficient；Bessel-Gaussian beam；confined Brownian motion；differential dynamic microscopy

中图分类号：O436.3                            文献标志码：A

文章编号：1008-5548(2022)04-0036-07

DOI:10.13732/j.issn.1008-5548.2022.04.004

收稿日期： 2022-01-07， 修回日期：2022-05-12，在线出版时间：2022-06-22。

基金项目：国家自然科学基金项目，编号：61975058；广东省自然科学基金项目，编号：2019A1515011401。

第一作者简介：刘冬梅(1981—)，女，副教授，博士，硕士生导师，研究方向为光电技术与系统。E-mail：dmliu@scnu.edu.cn。

通信作者简介：韩鹏(1976—)，男，教授，博士，博士生导师，研究方向为光电技术与系统。E-mail：hanp@scnu.edu.cn。