基于核(金属)/壳(介质)微球的单光束梯度阱模型, 计算了外面包覆较厚聚苯乙烯的铜微球在聚焦光场中的轴向散射力、梯度力以及合力, 分析了表面被高度氧化的铜微球的轴向捕获力。不同于纯金属米氏粒子, 外层包覆较厚介质材料的金属粒子在聚焦光场中容易被捕获但不能被捕获在聚焦光束的高强度区域。光学微操作实验显示: 高度氧化的铜微球能被聚焦的高斯光束捕获并可以在平面内移动。理论和实验结果便于研究核壳结构金属微粒的光学特性, 进一步拓展了光镊技术的应用范围。

The scattering, gradient and net forces exerted on the metallic microspheres with the thick shell were calculated and the axial trapping force exerted on the oxidized copper microspheres with a force model were analyzed for a single-beam gradient trap on a core-shell(metal/dielectric)microsphere. Unlike the case for a purely metallic Mie particle, a metallic microsphere with thick dielectric shell can be trapped easily, but not be trapped in the high intensity region of focused beam. In the experiment the copper microparticles coated with copper oxide can be trapped in the focused Gaussian beam and also transported horizontally. The optical characteristics of core-shell structured metal particles could be analyzed with the theoretical analysis and experimental results, which extend the applications of optical tweezers.