利用光镊捕获单个微小粒子,在各个研究领域得到重要应用。光镊也能同时捕获两个或更多个粒子,明确地知道光阱中粒子的个数,是顺利进行研究的前提。根据光散射原理,提出通过测量阱域内微小粒子的背散光强度来区分光阱中的粒子个数,实验上成功地实现了对直径分别为1 μm,0.5 μm,0.2 μm,100 nm和73 nm的被捕获于光阱中的粒子个数的分辨。对背散光光强随着粒子直径变化所反映的信息进行了分析,讨论了光阱中多粒子的排列状态。通过背散光实时动态分辨光阱中的纳米粒子个数的实验方法,对将光镊扩展到纳米尺度的应用提供了技术支持。

Optical tweezers have increasingly widespread application in a large variety of scientific disciplines because they can trap a micro-particle losslessly. They can also trap multiple particles in single optical trap due to the characteristic of the potential energy of the trap. How to distinguish the number of particles in single optical trap is the key work in the experiment. A novel method based on laser scattering method to distinguish the numbers of nanometer-particles in single trap was presented in this paper. The number of particles in single trap was distinguished by measuring the intensity of light backscattering with corresponding situation. The number of particles with diameters of 1 μm,0.5 μm,0.2 μm,100 nm,73 nm was distinguished successfully,and the state of optical trap was discussed. This method may find the application of optical tweezers in nanometer dimension.