利用光镊计算工具箱实现光镊系统的参量评价

光镊所捕获的微球尺度常常落在中间尺度上,导致相关参量难于计算.OTT1光镊工具箱是一种基于广义Lorenz-Mie理论的T-matrix方法,它的发展使得对光镊系统的详细计算和评价成为可能.本文对光镊的轴向捕获特性曲线、线性性和刚度,以及杜克系列微球的互换性做了计算和评价.结果表明:光镊所用物镜的数值孔径越接近水的折射率捕获效果越好;0.8~1.2 μm的聚苯乙烯微球组成的光镊刚度较大;直径在2 μm以下的聚苯乙烯微球组成的光镊线性度较好;0.8~2 μm的Duke系列聚苯乙烯微球的互换性较好,便于纳米光镊的修正与实验;要避免米共振微球的直径要在2.5 μm以下.

Parameter Evaluation of Optical Tweezers System Using Optical Tweezers Computational Toolbox

Because the diameter of the trapped sphere obtained by the optical tweezer usually locates in the intermediate range, theoretical calculation was difficult. OTT1 optical tweezers computational toolbox is a kind of T matrix method based on the GLMT theory. The development of the OTT1 optical tweezers computational toolbox makes detailed calculation and evaluation feasible. In this paper, the optical trapping coefficiency curve, its linearity and stiffness, and the interchangebility of Duke series polystyrene sphere were calculated and evaluated. The results show that when the numerical aperture becomes closer to the refractive index of water, a better trapping effect will be achieved; when an 800~1 200 nm polystyrene sphere is trapped, the stiffness of optical tweezers is larger; when a PS sphere with diameter smaller than 2 000 nm is used, the linearity of optical tweezers is better; when Duke series sphere with a 800~2 000 nm diameter is adopted, the interchangeability between the same series spheres is better, which will be convenient to calibrate the nanometer optical tweezers; for avoiding Mie resonance, the sphere diameter should be smaller than 2 500 nm.