标题: 雷射偏振态对雷射镊夹捕捉力影响之研究
Study of the laser polarization dependence upon the trapping force of optical tweezers
作者: 蔡玉堂
徐琅
电子物理系所
关键字: 雷射镊夹;optical tweezers;trapping force
公开日期: 2004
摘要: 当我们想要量化生物力时,雷射镊夹是一项很有用的工具。然而当我们对于量化生物力的准确度越来越要求时,我们就需要更精确地估计雷射镊夹捕捉力。而现有几何光学模型的理论模型之预期,并不符合在我们系统的雷射镊夹系统中,X轴捕捉力总是比Y轴捕捉力来的大的现象,所以我们希望能提出一个修正模型来解释这个现象。
相较原有的几何光学模型,在我们的修正模型中,我们额外考虑两种雷射光源的偏振态──圆形偏振态与线性偏振态。因此我们必须分析雷射光源的平行偏极化与垂直偏极化的比例。在我们修正模型的数值模拟中,雷射镊夹最大捕捉力X轴比Y轴大了15.4 %。另外,在雷射镊夹捕捉力线性区中,X轴光弹性系数比Y轴光弹性系数大了2.5 %。我们也利用水流黏滞系数法实际量测雷射镊夹X轴、Y轴捕捉力。在我们的实验值中,X轴光弹性系数比Y轴光弹性系数大了10 %左右。同时,数值模拟的预测值亦是包含于实验误差范围内。
Optical tweezers has become a useful tool for bio-medical research. Also, as the higher accuracy is required for biological force measurement, a more rigorous model of optical tweezers trapping force is necessary. However, the prediction of recent ray-optics model is not confirmed with our experimental result, that trapping force along with the x-axis is always larger than the one along with the y-axis. Therefore, a more correct model is required to describe this phenomenon.
Comparing with the recent ray optics model, in our revise model, we further consider the two different kinds of laser polarizations, a circular polarization and a linear polarization. Therefore, we have to analyze the ratio between transverse electric (TE) model and transverse magnetic (TM) mode. With this consideration, the maximum trapping force along with the x-axis is 15.4% larger than the one along with the y-axis. Also, the optical stiffness along with x-axis is 2.5 % larger than the one along with y-axis. Furthermore, we also measured the optical stiffness of our optical tweezers system, and there is 10% difference between the optical stiffness along the two axes. Additionally, it is also confirmed that the predictions of our model is within the experimental error.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT009221552
http://hdl.handle.net/11536/76135
显示于类别:Thesis