Manipulation on human red blood cells with femtosecond optical tweezers

Different types of femtosecond optical tweezers have become a powerful tool in the modern biological field. However, how to control the irregular targets, including biological cells, using femtosecond optical tweezers remains to be explored. In this study, human red blood cells (hRBCs) are manipulated with femtosecond optical tweezers, and their states under different laser powers are investigated. The results indicate that optical potential traps only can capture the edge of hRBCs under the laser power from 1.4 to 2.8 mW, while it can make hRBCs turn over with the laser power more than 2.8 roW. It is suggested that femtosecond optical tweezers could not only manipulate biological cells, but also subtly control its states by adjusting the laser power.     

Polarization-dependent blue-shifted emissions in microstructure fibers

Trefoil and quatrefoil channels between air holes of two microstructure fibers can strongly confine light field and act as highly nonlinear waveguides. Polarization-dependent blue-shifted emissions of femtosecond Ti:sapphire laser pulses were carried out in these channels. The spectra bandwidth of blue-shifted emissions in a trefoil channel is narrower than 10 nm and can be tuned slightly by altering the polarization state of pump light. Polarization-dependent blue-shifted emissions from a quatrefoil channel lie in a hollow beam having potential use in optical tweezers.     

近场光镊技术研究新进展

光镊技术,又称光学捕获技术,它是利用光的辐射压力来捕获和操纵包括电介质颗粒、生物细胞及生物大分子在内的微小粒子的。近场光镊技术利用近场光学倏逝场随距离急剧衰减的特征,可显著地降低捕获粒子的尺寸,实现纳米捕获。追踪了近场光镊技术的最新进展,包括全内反射相干倏逝场、近场光学镀膜光纤探针尖、激光照明金属探针尖和聚焦倏逝场用于近场光学捕获,并对其进行了比较,分析了它们存在的主要问题和未来发展方向。     

激光诱导等离子体加工石英微通道机理研究

利用调Q的Nd: YAG激光器输出的纳秒激光脉冲诱导等离子体加工石英微通道, 显微镜下观察微通道深度可达4 mm, 通道周围没有发现热裂纹, 围绕通道内壁产生了固化层. 研究了纳秒脉冲下固体材料损伤的电离机理. 波长为1064 nm, 光强不很强的纳秒脉冲作用时, 光学击穿中等离子体的形成主要是雪崩电离的结果, 利用雪崩击穿的阈值理论得到了等离子体形成模型, 求出了等离子体形成范围, 理论模型结果与实验结果基本相符.最后基于激光支持的爆轰波模型, 利用流体力学理论求出了等离子体的温度、 速度、 压强等特征参数, 并分析了微通道的特点.高温高压的等离子体烧蚀出石英微通道, 等离子通过后, 在冲击波压力作用下微通道内壁熔化的 石英凝固形成固化层.     

阵列光镊的发展与应用

在生命科学研究中和在微量液体环境下分离液体中的细胞、生物大分子或胶体颗粒一直是一项具有挑战性的工作。"光镊"技术自20世纪80年代被提出到现在,在生命科学研究领域已经得到了日益广泛的运用。激光对细胞捕获的作用已得到进一步扩展,二维"光镊阵列"技术是近年来"光镊"技术中最重要的发展之一。讨论了阵列光镊的发展现状及基本原理,分析了它在生命科学中的应用,并对其发展趋势进行了展望。     

拼接式光学窗口装配关键技术研究

对拼接式光学窗口组件的结构特点作了介绍,分析了影响拼接式光学窗口性能的主要装配因素,并从装配齐平性及微应力装调两个方面出发,开展了装配关键技术研究,通过计算分析及参数量化工艺措施解决装调技术难题,获得了装配后外形齐平性≤0.2 mm,装配后应力≤50 nm/cm的高精度、微应力装调效果,满足光学分辨率及高速飞行使用要求。     

伪随机码激光引信探测系统设计

半导体激光器件的激光近炸引信在各种导弹和常规弹药中已得到了广泛的应用。设计了基于伪随机码脉冲激光引信的实现方法,根据其工作原理,整个系统可分为发射模块、接收模块、光学系统和信号处理模块。对伪码激光引信各模块的具体构成进行了详细分析,得出了选择各模块参数的依据。结果表明,伪码激光引信能够满足战技指标要求,且具有较强的探测和抗干扰性能。该设计方法对伪码激光引信的研制具有一定的指导意义。     

Heterogeneous integration of InGaAsP microdisk laser on a silicon platform using optofluidic assembly

Heterogeneous integration of InGaAsP microdisk lasers on a silicon platform is demonstrated experimentally using an optofluidic assembly technique. The 200-nm-thick, 5- and 10-μm-diameter microdisk lasers are fabricated on InP and then released from the substrates. They are reassembled on a silicon platform using lateral-field optoelectronic tweezers (LOET). The assembled laser with 5-μm diameter exhibits a threshold pump power of 340 μW at room temperature under pulse condition. The heterogeneously-integrated InGaAsP-on-Si microdisk laser could provide the much needed optical source for CMOS-based silicon photonics. The small footprint and low power consumption make them attractive for optical interconnect applications. The optofluidic assembly technique enables efficient use of the III–V epitaxial materials in silicon photonic integrated circuits.     

Advanced optical trapping by complex beam shaping

Optical tweezers, a simple and robust implementation of optical micromanipulation technologies, have become a standard tool in biological, medical and physics research laboratories. Recently, with the utilization of holographic beam shaping techniques, more sophisticated trapping configurations have been realized to overcome current challenges in applications. Holographically generated higher‐order light modes, for example, can induce highly structured and ordered three‐dimensional optical potential landscapes with promising applications in optically guided assembly, transfer of orbital angular momentum, or acceleration of particles along defined trajectories. The non‐diffracting property of particular light modes enables the optical manipulation in multiple planes or the creation of axially extended particle structures. Alongside with these concepts which rely on direct interaction of the light field with particles, two promising adjacent approaches tackle fundamental limitations by utilizing non‐optical forces which are, however, induced by optical light fields. Optoelectronic tweezers take advantage of dielectrophoretic forces for adaptive and flexible, massively parallel trapping. Photophoretic trapping makes use of thermal forces and by this means is perfectly suited for trapping absorbing particles. Hence the possibility to tailor light fields holographically, combined with the complementary dielectrophoretic and photophoretic trapping provides a holistic approach to the majority of optical micromanipulation scenarios.     

飞秒光镊技术及其发展

激光捕获技术是利用光辐射力来捕捉、移动和操纵微粒的先进技术。飞秒光镊在实现粒子微纳操纵的同时还伴随着非线性现象的发生。阐述了飞秒光镊的模型和原理以及系统的各种结构形式,包括单光束梯度力光阱、贝塞耳光阱、双光束光纤光阱和冲击波光阱几种形式,并分析了每种形式的特点。     

激光捕获技术及其发展

激光捕获技术是利用光辐射力来捕捉、移动和操纵微粒的先进技术。光镊即单光束梯度力光阱是通过在高度会聚的激光束束腰附近所产生的极高的场强梯度来形成皮牛顿量级的力,可以三维地捕获和操纵微小粒子。阐述了激光捕获技术的模型和原理以及系统的基本结构;追踪了激光捕获技术的最新研究进展;介绍了非高斯型光阱、光纤光阱和全息光镊等几种特殊形式,并分析了每种形式的特点。展望了激光捕获技术的发展前景。     

有限远共轭显微镜光镊设计和误差分析

光镊是研究单分子生物物理特性的独特工具, 因而光镊设备的研发是一个极为重要的课题. 本文根据矩阵光学, 对基于有限远共轭显微镜的光镊操控光路进行计算, 得出了阱位径向操控和轴向操控方程, 并分析了光束调控系统、 共焦系统后置透镜和耦合透镜安装位置误差及物镜轴向位置调整对光镊阱位径向及轴向操控精度的影响. 计算结果显示, 当物镜初级像面和耦合透镜像方焦面完全重合, 光束调控系统和耦合透镜的距离误差对阱位径向和轴向操控精度没有影响. 光镊系统元器件定位不准时, 基于无限远共轭显微镜光镊的阱位径向操控误差和轴向操控误差都小于基于有限远共轭显微镜光镊的阱位径向操控误差和轴向操控误差. 当光镊耦合透镜定位误差控制在小于10 mm时, 基于有限远共轭显微镜光镊的径向和轴向操控误差分别小于5.9%和11.4%, 有限远共轭显微镜仍然存在改造为光镊的价值.本文理论为基于有限远共轭显微镜的光镊设计、改造和操控提供理论和实验指导. 关键词： 光镊 光学设计 矩阵 误差     

Optical tweezers for confocal microscopy

In confocal laser scanning microscopes (CLSMs), lasers can be used for image formation as well as tools for the manipulation of microscopic objects. In the latter case, in addition to the imaging lasers, the light of an extra laser has to be focused into the object plane of the CLSM, for example as optical tweezers. Imaging as well as trapping by optical tweezers can be done using the same objective lens. In this case, z-sectioning for 3D imaging shifts the optical tweezers with the focal plane of the objective along the optical axis, so that a trapped object remains positioned in the focal plane. Consequently, 3D imaging of trapped objects is impossible without further measures. We present an experimental set-up keeping the axial trapping position of the optical tweezers at its intended position whilst the focal plane can be axially shifted over a distance of about 15 μm. It is based on fast-moving correctional optics synchronized with the objective movement. First examples of application are the 3D imaging of chloroplasts of Elodea densa (Canadian waterweed) in a vigorous cytoplasmic streaming and the displacement of zymogen granules in pancreatic cancer cells (AR42 J). Received: 24 March 2000 / Revised version: 23 June 2000 / Published online: 11 October 2000     

Controlled rotation and orientation of rubrene particles and Escherichia coli using optical tweezers

Optical trapping and rotating of suspended micro-sized rubrene particles were performed using optical tweezers with circularly polarized light. The experimental results show that the rotation speed of the rubrene particles is proportional to the laser power, and the orientation of the rubrene particles can be controlled by the optical tweezers with linearly polarized light. Interestingly, by combining with the rubrene particle, the Escherichia coli (E. coli) can be rotated and oriented by optical tweezers. However, the rotating and orientating are mainly determined by the characteristics of rubrene particles. Our experiment provides a simple and convenient way to orient biological particles even if they are not sensitive to the polarization of the laser beam. Moreover, the rubrene can emit strong fluorescence when excited by the laser at the wavelength of 532 nm, and which can be potential applied to manipulate other particles with the fluorescence characteristics.     

Probing of Ehrlich ascites carcinoma cell using in situ aggregates of Au-NPs as SERS label created by plasmon exciting hybrid-TEM*11 laser mode

Apart from commonly employed target-specific labeling/adsorption of antibodies over Au-NPs surface for the creation of localized aggregates, an alternative approach using optical tweezers (OT) driven by hybrid-TEM*₁₁ mode has been devised and exploited for in vitro detection of Ehrlich ascites carcinoma cells (EAC) relying on enhanced scattering. Intra-cavity generated spatially featured asymmetric (SFA) laser beam (λ = 532 nm) has effected simultaneous trapping of mice-EAC cells and in-situ crowd/assembly of incubated Au-NPs/small gold nano-aggregates (created from two or more individual Au-NPs). Relatively larger focus spot created by tightly focused SFA beam than frequently employed Gaussian-mode in OT has offered an extended working area and hence dilute heating has taken care of EAC cells. GNA improves significantly the sensitivity of diagnostics relying on scattered light and the safety and efficacy of therapeutic nanotechnologies for the diseases of cancer and vascular system in medicine.     

考虑光镊效应的飞秒激光双光子加工线宽

采用自由基浓度起伏理论结合光镊集聚效应,理论研究了飞秒激光双光子加工的线宽问题。根据双光子光聚合过程中自由基浓度随时间变化的关系,考虑光镊效应对自由基分布范围的影响,得到了飞秒激光双光子加工线宽的表达式。研究了线宽随扫描速度与激光功率的变化关系,并讨论了不同光引发剂对线宽的影响。得到了以自由基浓度起伏为基础,并考虑光镊效应的双光子加工线宽表达式,该结果与实验结果相符。研究结果为飞秒激光双光子加工的研究提供了新的思路,为光镊集聚效应对线宽影响的实验研究提供了理论依据。     

Theoretical study of the trapping efficiency of an optical tweezers array system

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.     

空间激光通信中湍流信道光束传输仿真

对大气光信道特性的研究是空间激光通信研究的重要组成部分。首先以大气湍流理论为基础,阐述了激光在大气中传输时受到的大气湍流的影响和分析方法。接着重点对近年来应用日益广泛的空间激光通信的数值仿真方法进行了综述。不仅介绍了基本传输方程及其求解方法,还对采用数值方法模拟光波在随机介质中传播的若干关键技术进行了分析。最后结合现有的研究成果,说明了数值方法在空间激光通信中的应用。     

Controlled trapping and rotation of carbon nanotube bundle with optical tweezers

Controlled optical trapping and rotation of carbon nanotube bundle (CNTB) including single-walled and multi-walled carbon nanotube in aqueous solution, were performed using the optical tweezers. Vertical and horizontal trapping of CNTB was performed depending on the size of CNTB and the trapping depth. In addition, four different rotations of the trapped CNTB were described and explained by the interaction between CNTB and the laser field, and the convection of the aqueous solution induced by thermalphoresis effect. These results will pave the way to assemble some CNTs-based devices such as micro motors.     

分布式激光告警与诱骗系统设计

激光制导武器是现代战争中各类作战平台和重点目标的主要威胁之一,针对多批次饱和攻击的对抗需要以及不同平台和目标需要保护的范围和部位差异较大的特点,设计了一种分布式的激光告警与诱骗系统,并分析了系统实现的体系结构与关键技术。