四种光阱刚度测量法的实验研究与比较

The Experimental Research and Comparison of Four Methods to Measure the Optical Trap Stiffness

通过对光阱刚度的测量原理、方法及其特点进行分析,对多种光镊刚度标定方法进行了比较,分析了不同方法的精度和适用范围,总结了各种方法的优缺点.其中,流体力学法简单易行,但是误差较大;外加周期驱动力法精度较高,不需要测量绝对位移,但是适用的微粒的直径范围有限;热运动分析法所需要的参数少,但是受到系统噪声影响较大;功率谱方法精度较高,且不需要测量出绝对位移,但是测量结果受到系统噪声影响较大.

The force measurement in piconewton and sub-piconewton range is related to the accurate measurement of trap stiffness. Several methods for measuring trap stiffness, the hydrodynamics method and thermal motion analysis method, power spectrum method, periodic external force method, were experimentally studied, and their characteristics were discussed. The hydrodynamics method is convenient, but it is not as accurate as others. The periodic external force method has a better precision and it does not need absolute displacement measurement, but the range of its measurement is very limited. The thermal motion analysis method needs the least parameters, but the results are greatly affected by the system noise. The power spectrum method has a better precision too, and it does not need the absolute displacement measurement, but, like the theramal motion analysis methods, it is also affected by the system noise.