共查询到17条相似文献,搜索用时 46 毫秒
1.
2.
3.
4.
5.
7.
本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路. 相似文献
8.
光镊是利用光穿过处于系统焦点的物体时产生的动量变化对其施加力的作用,因此确定光镊系统焦点位置是极其重要的.但目前缺少有效确定光镊焦点的方法.本文提出利用测量皮安培量级电流的膜片钳技术,基于光在溶液中产生的光热效应来确定光纤端面出射光斑的焦点.基于水的吸收光谱,选用波长为980nm、845nm和功率为100mW的激光作为光源.由于光热效应引起溶液电导的改变,影响流过玻璃微电极的电流,再用标准温度引起电流变化对膜片器放大器记录的电流标定,将电流值转换成温度值,获得微电极尖端点的温升值.用三维微操纵器控制玻璃微电极的空间位置,获得温度空间分布,从而确定该光斑焦点位置. 相似文献
9.
本文结合近场扫描结构和纳米线-微光纤耦合技术,提出了一种基于硫化镉纳米线/锥形微光纤探针结构的被动近场光学扫描成像系统.该系统采用被动式纳米探针,保留了纳米探针对样品表面反射光的强约束优势.其理论收集效率为4.65‰,相比于传统的金属镀膜近场探针收集效率提高了一个数量级,可有效地提高扫描探针对样品形貌信息的检测能力;而后通过硫化镉纳米线与微光纤之间高效的倏逝场耦合,将检测的光强信号传输到远场进行光电探测,最终实现对目标样品形貌的分析成像,其样品宽度测量误差在7.28%以内.该系统不需要外部激发光路,利用显微镜自身光源进行远场照明,被动扫描探针仅作为样品表面反射光的被动收集系统.本文基于半导体纳米线/锥形微光纤探针的被动式近场光学扫描成像方案,可有效地降低探针的制备难度和目标光场的检测难度,简化扫描成像的结构,为近场光学扫描显微系统之后的发展提供新的思路. 相似文献
10.
光镊是利用光穿过处于系统焦点的物体时产生的动量变化对其施加力的作用,因此确定光镊系统焦点位置是极其重要的.但目前缺少有效确定光镊焦点的方法.本文提出利用测量皮安培量级电流的膜片钳技术,基于光在溶液中产生的光热效应来确定光纤端面出射光斑的焦点.基于水的吸收光谱,选用波长为980 nm、845 nm和功率为100 mW的激光作为光源.由于光热效应引起溶液电导的改变,影响流过玻璃微电极的电流,再用标准温度引起电流变化对膜片器放大器记录的电流标定,将电流值转换成温度值,获得微电极尖端点的温升值.用三维微操纵器控制玻璃微电极的空间位置,获得温度空间分布,从而确定该光斑焦点位置. 相似文献
11.
12.
13.
14.
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
15.
Size‐based particle sorting using a subwavelength optical fiber was demonstrated with 600‐nm and 1‐μm sizes of polystyrene particles. Optical forces acting on the particles were calculated based on three‐dimensional finite‐difference time‐domain simulations at wavelengths of 808, 1047, and 1310 nm propagating in a subwavelength optical fiber with diameter of 800 nm. Calculations indicate that by launching two counterpropagating laser beams at different wavelengths into the fiber, the directions of the resultant optical scattering forces acting on the two particle sizes can be opposite along the fiber, which leads to a countertransport of the particles. To verify the theoretical prediction, experiments were performed using the 800‐nm fiber to sort the two particle sizes. The results show that with two counterpropagating beams at 808 and 1310 nm, a continuous particle sorting was achieved. Measured particle velocities were in agreement with the theoretical calculations. 相似文献
16.
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
17.
A double tapered optical fiber sensor based on evanescent field-effect and surface modification technology was introduced in this work. Whether the liquid and gas molecules had polarities or not, they all could be detected by the sensors modified in different silane coupling agents. At the same time, the sensing characters of the single mode optical fiber with three different tapering lengths were researched, and it came to a conclusion that the optical fiber sensor had stronger evanescent field effect and higher sensitivity when length of tapered fiber was 30 mm. The functionalized tapered fibers modified by 3-aminopropyltrimethoxy silane (APTES) or 3-methylpropenylacyloxy propyltrimethoxy silane (MPAPTES), were employed to detect the polar or nonpolar molecules which had corresponding features. Further, the results of quantitative tests showed that the fiber optic sensor was sensitive to the change of the ethanol concentration and the characteristic peaks of the absorption power spectra could reach to 3–5 dB. 相似文献