时间飞行法测量光阱刚度的实验研究  

Calibration of optical tweezers using time of flight method

作　　者：周丹丹[1] 任煜轩[1] 刘伟伟[1] 龚雷[1] 李银妹[1] 

机构地区：[1]中国科学技术大学光学与光学工程系,合肥230026

出　　处：《物理学报》2012年第22期522-528,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:21073174;20974107;31100555);国家重大科学研究计划(批准号:2011CB910402);中国科学院微重力重点实验室资助的课题~~

摘　　要：传统的测量光阱刚度的方法如功率谱法是基于微粒的布朗运动,适用于直径范围几百纳米到几微米的微球,在几微米以上并不具有明显优势.本文发展一种时间飞行的方法测量光阱对微球的刚度.该方法是基于跟踪微粒的运动轨迹获得光阱刚度.通过比较不同功率下,不同大小以及不同材料的微球的光阱刚度和误差,结果表明时间飞行法适用于直径范围5–10μm的微球;论文中用功率谱法和均方位移法测量了5μm标准聚苯乙烯小球的光阱刚度与时间飞行法测得的结果作为对比,由于受相机采集速率的影响,所测刚度值比理想值偏高,比较而言,时间飞行法的测量结果更加接近于真实值,对于光阱刚度的快速标定有着重要意义.该方法可以应用在特殊光场分布的激光阱中测量微球的光阱刚度;在实现细胞层次的力学特性测量中它可避免使用微球作为探针,为更深层次研究细胞上的复杂单分子过程提供了一个研究手段.Conventional method of calibrating optical trap stiffness is applicable for microspheres whose diameters range from hundreds of nanometer to several micrometers, but only have a slight advantage for those microspheres with diameters lager than five micrometers. To compensate this, we experimentally develop a time of flight method for measuring optical trap stiffness with larger microspheres. By comparing the optical trap stiffness of microspheres with different sizes and different materials at different laser powers, the time of flight method is confirmed to be more accurate and practical for microspheres larger than 5 btm; the result is of the same order of magnitude as the results of Brownian noise based analysis of 5 btm polystyrene bead. The results are higher than theoretical values due to the limited bandwidth of the camera. In comparison, the time of flight method is superior to other methods and does make sense in the fast calibration of optical trap stiffness on cell level. This method can be applied to optical traps with special field distributions. In the measurement of mechanical properties of ceils, it can avoid using microspheres as force probe, thus providing a novel approach to the study of sophisticated single molecule process on the membrane of cells.

关 键 词：光镊 光阱刚度 时间飞行法 细胞 

分 类 号：O439[机械工程—光学工程]