光镊力谱系统双光束串扰因素研究  

Crosstalk Factors of Dual Beams in Optical Tweezers Based Force Spectrocopy System

作　　者：胡春光[1] 王国庆[1] 李宏斌[1,2] 胡晓东[1] 胡小唐[1] 

机构地区：[1]天津大学精密仪器与光电子工程学院,天津300072 [2]加拿大英属哥伦比亚大学化学系

出　　处：《纳米技术与精密工程》2017年第3期168-174,共7页Nanotechnology and Precision Engineering

基　　金：国家自然科学基金资助项目(61223008);天津市自然科学基金资助项目(15JCZDJC31600)

摘　　要：为了降低和消除光镊力谱系统中双光阱之间的干扰,进一步提高测试精度,本文对双光阱光镊系统中两光束间串扰的成因及其对力谱测量的影响展开了研究.研究发现,高倍物镜组与样品池构成的光学结构会引起光束偏振态的改变,是双光束串扰形成的主要因素;偏振分光棱镜自身的分光特性是串扰产生的另一因素;光阱捕获的微球,虽然改变了光束的形状和传播方向,但在光束串扰方面贡献很小.双光束的串扰信号叠加在探测的光强信号上,影响了光阱刚度和位移灵敏度的标定,最终导致力学测量的偏差.光镊系统中双光束的串扰量在同一次实验的一定时间内基本稳定.根据双光阱光镊系统的这一特点,本文提出了实时测量双光阱光镊系统两光阱独立存在时和同时存在时双光阱的刚度和位移灵敏度的方法,并经多次实验求平均后得到两种情况下双光阱的刚度和位移灵敏度的比值,在后续实验中,将该比值作为修正参数对实测的力谱曲线进行修正.结果表明,该方法有助于减小双光束串扰的影响,优化力谱测量结果,测试精度提高3.4!.For the purpose of reducing and eliminating the effect between the dual traps, and of impro- ving the test precision, the cause of crosstalk between the two beams and its influence on the measure- ment of force spectroscopy are studied in this paper. Results show that the structure built by high NA ob- jective and specimen chamber can change the laser＇ Another factor is leakage of polarization dispersion s polarization, which is the main cause of crosstalk. prism. Microspheres captured by optical trap can change the shape and propagation direction of the beam, which makes little contribution to crosstalk. Crosstalk between the two beams disturbs the signal of the detector, induces error to the process calibra- tion of trap stiffness and displacement sensitivity, and decreases the accuracy of force measurement. In addition, the crosstalk signal exerts a stable interference on the experimental parameters in each experi- ment within a certain time period. Based on this principle, this paper puts forward a method of real-time measurement of dual optical trap tweezers system＇ s trap stiffness and displacement sensitivity, when the dual traps exist independently and when they exist simultaneously. After averaging several repeated ex- perimental results, the ratio of trap stiffness and that of displacement sensitivity can be obtained in both cases. In subsequent experiments, the ratios will be used as correction parameters to modify the measured power spectrum curves. Results show that the method is helpful to reduce the influence of erosstalk be- tween the two beams and can optimize the measurement of force spectroscopy, improving about 3.4% of the test data accuracy.

关 键 词：光镊力谱 双光阱 串扰 参数修正 

分 类 号：TH74[机械工程—光学工程]