共查询到19条相似文献,搜索用时 93 毫秒
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用三维时域有限差分法对光镊装置中介质球微粒所受光阱力情况进行模拟。根据Richards-Wolf矢量场衍射积分公式对消球差会聚透镜像空间中电磁场分布的表示,在总场空间中实现了对聚焦光脉冲的模拟。聚焦光脉冲与介质球微粒的相互作用,通过离散傅里叶变换提取出单频成分,利用计算光阱力的麦克斯韦应力张量公式,计算单频激光对介质球的光阱力。聚焦光脉冲的引入可以使一次计算得到多个频率下的计算结果。对相同的聚焦装置下介质球受不同频率入射光的光阱力情况进行了计算。计算结果表明使用线偏振光作光源时,大数值孔径聚焦透镜和短入射波长有利于介质球的横向操纵;沿光轴方向对介质球进行纵向操纵,需要大数值孔径的物镜和与之相适应的入射波长。 相似文献
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非均匀偏振光束通过环状光阑像散透镜的聚焦特性 总被引:4,自引:3,他引:1
借助于光束相干偏振矩阵和广义惠更斯-菲涅耳衍射积分公式,研究了非均匀偏振(NUP)光束通过环状光阑像散透镜的聚焦特性,并将圆孔光阑作为环状光阑内径为零的特例处理.数值计算结果表明,实际焦点位置、光强和偏振度分布与透镜的像散、环状光阑的菲涅耳数和遮拦比以及NUP光束参量有关. 相似文献
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基于Tovar提出的平顶多高斯光束模型,给出了环状光束模型。利用广义惠更斯-菲涅耳衍射积分理论,对环状光束通过像散透镜后的传输和聚焦特性进行计算和分析,并讨论了透镜像散对环状光束经透镜变换后对光束质量的影响。研究结果表明:环状光束通过像散透镜后变为非旋转对称光束;聚焦光强随着透镜像散系数的增大而逐渐减弱,聚焦光斑的方位仅由像散系数确定;在光束阶数和入射光波波长一定的情况下,环状光束通过像散透镜的变换特性和光束质量不仅与透镜像散系数有关,还与系统菲涅耳数有关,像散系数增大或菲涅耳数减小时,光束质量变差。 相似文献
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推导出了离焦量与聚焦误差信号功率的关系式。利用MATLAB软件仿真,详细分析了像散透镜系统各个参数对离焦量、灵敏度、光斑大小等的影响,得到了像散圆透镜与像散柱透镜焦距之间的距离关系。结果发现聚焦物镜和探测器参数对最小离焦量、灵敏度、精度有决定性的影响。提出了像散透镜系统各光学参数选择的原则和方法,并以德国Silicon Sensor公司的QP50-6型四象限探测器为例,详细分析了离焦量与聚焦误差信号功率的线性关系。这些工作对建立满足应用对象要求的像散法离焦检测系统具有重要的指导意义。 相似文献
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基于Tovar提出的平顶多高斯光束模型,给出了环状光束模型。利用广义惠更斯-菲涅耳衍射积分理论,对环状光束通过像散透镜后的传输和聚焦特性进行计算和分析,并讨论了透镜像散对环状光束经透镜变换后对光束质量的影响。研究结果表明:环状光束通过像散透镜后变为非旋转对称光束;聚焦光强随着透镜像散系数的增大而逐渐减弱,聚焦光斑的方位仅由像散系数确定;在光束阶数和入射光波波长一定的情况下,环状光束通过像散透镜的变换特性和光束质量不仅与透镜像散系数有关,还与系统菲涅耳数有关,像散系数增大或菲涅耳数减小时,光束质量变差。 相似文献
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光的力学效应及光阱力的测量 总被引:2,自引:2,他引:0
介绍一个利用光镊技术直观地演示光的力学效应的实验。简要讨论了开设这一实验的背景和目的,给出了光镊原理、实验装置、光阱力的测量方法和实验安排。 相似文献
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光阱刚度是描述光镊对粒子进行操控的重要力学指标,实际使用过程中会受到激光功率的影响。采用均方位移法及玻尔兹曼统计法对搭建的光镊系统进行光阱刚度的标定,利用图像采集方法进行微粒位移的测量,并对两种方法的测量结果进行了比较。为了提高光阱刚度的标定结果的准确性,分析了光路放大倍数、温度变化对最后标定结果的精度影响。结果表明,两种方法进行标定的结果基本相同;光阱刚度在低激光功率(1 mW ~20 mW)范围时随功率近似线性增加,在高功率情况下(25 mW~60 mW)随功率增加不再线性增加,而是趋于一个饱和值。此外,光路放大倍数标定的精确性对标定的精度影响较大,10%的相对误差时,标定结果产生23%的变化,温度对标定的精度影响较小,0.1 ℃的温度变化导致标定结果0.034%的变化。 相似文献
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本文采用三维时域有限差分法(FDTD)和Maxwell应力张量法建立了单光镊在焦点附近俘获球形微粒的光阱力模型,采用基于球矢量波函数(VSWF)的五阶高斯光源作为仿真光源,得到了准确的光场传播.讨论了光源的波长、束腰、偏振态和微球的半径、折射率对光阱力的影响,分析了在单光镊俘获微球时,邻近微球对光阱力的影响.特别研究了光源的偏振态对微球所受光阱力的作用效果,仿真结果表明圆偏振光比线偏振光对微球的俘获力更大;被光镊稳定俘获的微球,会受到邻近微球干扰,失去平衡状态,改变光源的偏振态可以改变微球的受力状态.
关键词:
光镊
光阱力
介质微球
时域有限差分法(FDTD) 相似文献
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Systematical study of the trapping forces of optical tweezers formed by different types of optical ring beams 总被引:2,自引:0,他引:2 下载免费PDF全文
The technique of optical tweezers has been improved a lot since its
invention, which extends the application fields of optical tweezers. Besides
the conventionally used Gaussian beams, different types of ring beams have also been
used to form optical tweezers for different purposes. The two typical
kinds of ring beams used in optical tweezers are the hollow Gaussian beam and
Laguerre--Gaussian (LG) beam. Both theoretical computation and experiments
have shown that the axial trapping force is improved for the ring beams
compared with the Gaussian beam, and hence the trapping stability is
improved, although the transverse trapping forces of ring beams are smaller
than that of Gaussian beam. However, no systematic study on the trapping
forces of ring beam has ever been discussed. In this article, we will investigate
the axial and transverse trapping forces of different types of ring beams
with different parameters systematically, by numerical computation in which
the ray optics model is adopted. The spherical aberration caused by the
refractive index mismatch between oil and water is also considered in the
article. The trapping forces for different objectives that obey the sine
condition and tangent condition are also compared with each other.
The result of systematical calculation will be useful for the applications
of optical tweezers formed by different types of ring beams. 相似文献
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Experimental measurement and analysis of the optical trapping force acting on a yeast cell with a lensed optical fiber probe 总被引:1,自引:0,他引:1
Based on an optical trapping system with a single-lensed fiber probe inserted at an angle, the sub-picoNewton trapping force acting on a yeast cell as a function of the displacement is measured experimentally by the static and dynamic methods, respectively, whose measurement processes are presented in detail. The measured maximum trapping efficiency is 0.07 in our experiment, which is an order of magnitude lower than that of the optical tweezers. The characteristics of the trapping force in the various horizontal directions are discussed. Finally, the analysis of the measurement error shows the factors and their magnitude which cause error, and offers a way to reduce the error in future. 相似文献
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A dual optical tweezers system,which consists of a doughnut mode optical tweezer (DMOT) with the azimuthally polarised trapping beam and a solid mode optical tweezer (SMOT) with the Gauss trapping beam was constructed to compare the axial trapping effect of DMOT and SMOT.The long-distance axial trapping of ST68 microbubbles (MBs) achieved by DMOT was more stable than that of SMOT.Moreover the axial trapping force measured using the viscous drag method,was depended on the diameter of the particle,the laser power,and the numerical aperture (NA) of the objective lens.The measurement of the axial trapping force and the acquisition of CCD images of trapping effect confirmed that the DMOT showed excellent axial trapping ability than SMOT.A simple and effective method is developed to improve axial trapping effect using the azimuthally polarized beam as trapping beam.This is helpful for the long-distance manipulating of particles especially polarised biological objects in axial direction. 相似文献
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Optical tweezers have been a valuable research tool since their invention in the 1980s. One of the most important developments in optical tweezers in recent years is the creation of two-dimensional arrays of optical traps. In this paper, a method based on interference is discussed to form gradient laser fields, which may cause the spatial modulation of particle concentration. The parameters related to the optical tweezers array are discussed in detail and simulated by the Matlab software to show the influence of important parameters on the distribution of particle concentration. The spatial redistribution of particles in a laser interference field can also be predicted according to the theoretical analysis. 相似文献
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为了研究吸收双层球形微粒的横向光俘获,基于几何光学模型提出了双层带吸收球形微粒的光俘获模型,对TEM00模式高斯光束照射下外层有光吸收的双层电介质球形微粒受到的横向光俘获力进行了数值模拟,取得了光俘获力特性的一系列结果.结果显示,双层球形微粒的外层吸收系数对包括稳态俘获位置,峰值强度,稳态俘获的刚度等光俘获特性有很大影响.此外,内外径的比率对吸收双层球形微粒的光俘获特性也有调制性的影响.在一定条件下,带吸收的双层球形微粒可以被俘获在光轴上,也可能被俘获在中心在光轴上的圆环上.
关键词:
光俘获
几何光学模型
高斯光束
吸收双层球 相似文献