给出了一种实现稳定捕获微小粒子及其显微成像的单光束光镊实验系统，基于此系统研究了单个二氧化硅微球的 动态捕获过程.实验中发现要稳定捕获粒子的同时还能够实时观察粒子的运动变化，必须保证物镜的聚焦平面与CCD 的成像 平面重合.其次，聚焦物镜的数值孔径与激光功率的大小，对实现粒子的稳定捕获具有重要的影响.实验结果与理论分析表明 物镜的数值孔径越大、激光功率越大，粒子的捕获力越大，可实现微粒的稳定捕获.此研究有望在大学物理教学及生物的微操 控领域具有一定的参考价值.

A single-beam optical tweezers experimental system is presented，which can be used to trap some tiny particles stably and also realize microscopic imaging. Based on this system， the dynamic capture process of single silica microspheres is studied.It is found from experiments that the focal plane of the objective lens and the imaging plane of the CCD must be in a same plane when the particles are captured and imaged at the same time.In addition， the effect of the numerical aperture of the focusing objective lens and the power of the laser for stable trapping of the particles are also found in the experiment.Both experimental results and theoretic analyses indicated that the larger of the numerical aperture and the greater of the laser power leaded to enlarge the capture force of the particles，so the particles can be stably captured.This study is helpful in the field of college physics teaching and biological micro-manipulation.