Laser Micro-beam Manipulation System for Cells

This paper introduces a laser micro-beam system for cells manipulation. The laser micro-beam system comprises a laser scissors and a laser tweezers, which are focused by a Nd∶YAG laser and a He-Ne laser through a microscope objective, respectively. Not only the overall design of the laser micro-beam system is discussed, but also the design and choice of the critical components. A laser micro-beam system was constructed and anticipated experiment results were gained. Yeast cells can be successfully manipulated with the laser tweezers. Chromosomes can be successfully incised with the laser scissors.     

Laser Micro-beam Manipulation System for Cells

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｎｔｈｅｇｅｎｅｅｎｇｉｎｅｅｒｉｎｇ ,ｔｈｅｂａｓｉｃｇｅｎｅｉｎｓｔｒｕｍｅｎｔｓｕｓｅｄｉｎｔｈｅｗｏｒｌｄａｔｐｒｅｓｅｎｔａｒｅ“ｍｉｃｒｏｓｃｏｐｅｍａｎｉｐｕｌａｔｉｏｎｉｎｓｔｒｕｍｅｎｔｓ” .Ｔｏｔｈｉｓｋｉｎｄｏｆｉｎｓｔｒｕｍｅｎｔｓ,Ｔｈｅｒａｔｉｏｏｆｍａｎｉｐｕｌａｔｉｏｎｓｕｃｃｅｓｓｉｓ ｇｒｅａｔｌｙａｆｆｅｃｔｅｄｂｙｆａｃｔｏｒｓｆｒｏｍｔｈｅｏｐｅｒａｔｏｒｓｂｅｃａｕｓｅｏｆｍａｎｕａｌｍａｎｉｐｕｌａｔｉｏｎａｎｄｃｏｎ…     

射频板条CO2激光器输出光束的光学变换

射频激励板条CO2激光器输出激光近场光斑近似为一条线,远场光斑为O形图样。在垂直于光束传输方向的平面内,光束在一个方向发散很大,无法用于激光加工。根据激光器不同的激光功率级别及光束尺寸,分别采用了圆柱面镜、滤波光阑、扩束望远镜等不同组合的方法,将200 W激光器输出光束变换成远场光束为Φ6、近似TEM00模的圆形光束,500 W激光器远场光束为Φ10的低阶模的圆形光束。成功用于激光切割。     

10 ps High Power Laser System at 248 nm

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｎｒｅｃｅｎｔｙｅａｒｓｔｈｅｒｅｈａｓｂｅｅｎａｎｉｎｔｅｎｓｉｖｅｅｆｆｏｒｔｄｉｒｅｃｔｅｄｔｏｗａｒｄｔｈｅｐｒｏｄｕｃｔｉｏｎｏｆｓｈｏｒｔｐｕｌｓｅ,ｈｉｇｈ ｐｏｗｅｒＵＶｌａｓｅｒｓｙｓｔｅｍｓ .ＫｒＦｌａｓｅｒ,ｗｉｔｈｉｔｓ～ 2ｎｍｂａｎｄｗｉｄｔｈ ,ｈｉｇｈｅｌｅｃｔｒｉｃａｌ ｔｏ ｏｐｔｉｃａｌｃｏｎｖｅｒｓｉｏｎｅｆｆｉｃｉｅｎｃｙａｎｄｉｔｓｕｎｂｏｕｎｄ ｇｒｏｕｎｄｓｔａｔｅ ,ｉｓａｎａｔｔｒａｃｔｉｖｅｃａｎｄｉｄａｔｅｆｏｒｔｈｅ…     

10 ps High Power Laser System at 248 nm

A simple 10 ps KrF laser system consisting of quenched dye laser oscillator pumped by a XeCl laser, a distributed feedback dye laser (DFDL), a three-stage dye amplifier and a two-stage KrF amplifier are described. The output of the laser system is 140 mJ with 10 ps pulse width by using polarization-multiplexing amplification. A focused output laser intensity of about 4×1015 W/cm2 is obtained. The saturation fluence for KrF laser is obtained with this laser.     

An intermittent frequency offset lock of a transverse Zeeman laser to an iodine stabilized He-Ne laser

A single-mode frequency stabilized laser with modulation-free and moderate power is desired as a light source for an ultra-high resolution interferometer system and/or a rapid laser calibration system. For this purpose, we developed a new stabilized laser system that utilizes intermittent control of a 2 mW transverse Zeeman stabilized He-Ne laser (Zeeman laser) with an iodine stabilized He-Ne laser (I2 stabilized laser). Because of the intermittent control, working time of the I2 stabilized laser is reduced. The Zeeman laser has two operational modes: independent and slave mode. In the independent mode, the Zeeman laser is stabilized through control of Zeeman beat frequency. Temperature dependent drift of the oscillation frequency during the independent mode is periodically corrected by the slave operation utilizing frequency offset locking to the I2 stabilized laser. Frequency instability of the Zeeman laser in independent and slave modes is 7.7X10-11 and 2.0X10-11, respectively, at the sampling time of 100 s.     

半导体泵浦铷蒸气激光器出光实验

针对中心波长780 nm的商用连续波半导体激光器,使用斩波器将连续激光变为脉冲输出形式,用2400 line/mm的平面全息光栅搭建Littrow外腔将线宽压窄至0.2 nm以下。采用透镜组对线宽压窄后的半导体激光进行光束整形,半导体激光经线宽压窄和光束整形后,经透镜聚焦进长约8 mm的铷蒸气泡进行半导体泵浦碱金属激光实验。首次出光得到17.5 mW的基模线偏振铷激光;在最新的改进实验中,半导体泵浦铷激光输出功率已达到2.8 W。     

利用单飞秒激光脉冲驱动类氖钛X射线激光的研究

提出了一种利用单飞秒激光脉冲驱动类氖钛X射线激光的物理方案.利用自相似方法研究了不同脉冲前沿的单飞秒激光辐照钛平板靶产生的类氖钛X射线激光等离子体的特性,得到了电子温度、电子密度和定标长度三者的定标律,讨论了给定输入参数下各定标律曲线的特性.研究表明,利用单个飞秒激光能够实现X射线激光的产生,而且脉冲前沿强度随时间增长平缓的飞秒激光有利于驱动X射线激光.本研究为实验上实现单飞秒激光脉冲驱动X射线激光提供了一种新的方案.     

Synchronous Injection Locking Operation of Monolithic Diode Lasers Mode-Locked Diode Lasers

Synchronized mode-locking of monolithic mode-locked diode lasers has been demonstrated by injecting the light output from a master monolithic mode-locked diode laser. The master diode laser is a 10 GHZ hybridly mode-locked two section InGaASP quantum well laser. The slave lasers are a 10 GHz two section laser which is similar to the master laser, and a 20 GHz three section colliding pulse mode-locking laser. Both the slave lasers were greatly stabilized at 10 GHz frequency by a synchronous mode-locking mechanism under the injection of master laser pulses.     

高效频率转换下双波长外腔共振和频技术研究

基于外腔的高效频率转换, 尤其是当系统运行在抽运不消耗近似机理下, 信号光可实现大于90%的转换, 因此无法通过信号光直接获得其到腔模频率锁定的误差信号. 本文通过对信号光调制、和频光解调的方法获得了该误差信号, 实现了双波长激光到外腔腔模的级联锁定. 实验中外部环形腔将1.3 W的1064 nm抽运光放大到约14.3 W. 当1583 nm信号光从10 μW变化到50 mW, 其到636 nm和频光的转化效率约为73%; 当从50 mW变化到295 mW时, 转换效率呈线性降低到60%, 最终获得了440 mW的636 nm激光.     

All-solid-state narrow-linewidth 455-nm blue laser based on Ti:sapphire crystal

A compact, all-solid-state, narrow-linewidth, pulsed 455-nm blue laser based on Ti：sapphire crystal is developed. Pumped by a 10-Hz, frequency-doubled all-solid-state Nd：YAG laser and injection-seeded by an external cavity laser diode, the narrow-linewidth 910-nm laser with pulse width of 20 ns is obtained from a Ti：sapphire laser. 3.43-mJ blue laser can be obtained from the laser system by frequency-doubling with BBO crystal. This research is very useful to determine the roadmap of developing the practical, high power blue laser. This kind of laser will have potential application for underwater communication.     

Tandem-pumped 1120-nm actively Q-switched fiber laser

We report on a tandem-pumped actively Q-switched fiber laser system emitting at 1120 nm.Parasitic oscillation is challenging in Yb-doped Q-switched 1120-nm fiber laser,which is suppressed by pumping with a fiber laser at 1018 nm.At least four times improvement in output peak power is demonstrated in a single laser setup with 1018-nm fiber laser pumping instead of 976-nm laser diode pumping.This is,to the best of our knowledge,the first demonstration of a tandem-pumped Q-switched fiber laser.     

A miniature electron beam pumped laser

The 1.73 μm XeI laser has been operated in a fully continuous mode using a table-top electron beam pumped laser setup. A 12 keV electron beam sent through a 300 nm thick silicon nitride membrane into a laser gas mixture of typically 600 mbar gas pressure was used for pumping. A low loss cavity was installed, resulting in a very low pumping power of 37 mW to reach laser threshold. The geometrical conditions for the laser setup such as the shape of the beam pumped volume and its overlap with the optical mode volume are discussed. The laser scheme has been clearly identified as a recombination laser scheme by operating the laser in pulsed mode and observing the time structure of the laser pulse.     

利用波导调制器实现连续可调任意整形激光脉冲

目前，惯性约束聚变激光驱动哭有级的发展方向是以稳定性好的激光二极管取代原来的闪光灯泵浦，以集成光学和光纤技术取代原来的块状光学调制器进行激光脉冲的整形工艺。本文从实验上研究了以激光二极管泵浦的固体激光器作为光源，以波导调制器作为整形器件的激光脉冲的整形和频谱展工技术，获得了初步的实验结果。     

Removing paint from a metal substrate using a flattened top laser

In this paper,we investigate laser cleaning using a flattened top laser to remove paint coating from a metal substrate.Under the irradiation of a flattened top laser,the coating paint of the metal substrate can be removed efficiently by laser induced ablation,stress,and displacement force.The temperature distribution,stress,and displacement are calculated in the coating layer and substrate using finite element analysis.The effects of a Gaussian laser and a flattened top laser and the results of different diameters of laser spot are compared.The investigation shows that the flattened top laser can reduce the substrate damage and enhance the cleaning efficiency.This method meets the need of large area industrial cleaning applications by optimizing the flattened top laser parameters.     

Laser systems specialized for laser spectroscopy at storage rings

Laser spectroscopy at storage rings often suffers from a limited resolution due to Doppler-broadened resonances. Broadening is caused by the velocity spread of the ions stored in the beam. In the following, the present status of our work on laser systems specialized on the specific needs of laser spectroscopy at storage rings is reported. Two pulsed laser systems were developed. One is a dye laser whose spectral bandwidth can be switched by inserting different Littrow-prisms into the resonator. An increase in bandwidth up to a factor of 45 was achieved. This laser was used for fast qualitative scans and high resolution measurements. The other laser system is a Nd : YAG laser pumped optical parametric oscillator. It is a tunable laser system covering the spectral range from 410 to 4000 nm. Furthermore, a continuous wave laser with a frequency shifted feedback cavity is described. It shows broadband emission with an adjustable bandwidth of up to 4.5 GHz. This laser can be advantageous for laser cooling of ion beams. This revised version was published online in August 2006 with corrections to the Cover Date.     

Generation of nearly transform-limited pulses in subnanosecond region with TEA nitrogen-laser-pumped dye laser

A dye laser is transversely pumped by a TEA nitrogen laser with 700 ps duration. The dye laser pulse has a spectral linewidth of 0.007 nm and a pulse width of ≈ 140 ps, giving a time-bandwidth product of 1.5. It is pointed out that the fluorescence lifetime of the laser dye plays an important role in generation of laser emission using a long laser cavity under subnanosecond pulse pumping.     

连续和重复频率激光对旋转壳体加热效率的数值模拟

 基于有效利用激光能量的目的,采用有限元分析方法分析并比较了重复频率和连续激光对旋转壳体的加热效率。数值计算结果表明：重复频率激光要比连续激光的加热效率高,而且加热效率与重复频率、占空比等有关;在平均功率密度相同的前提下,在频率相同条件下,占空比减小,温度上升加快,即加热效率随占空比的减小而增大;在相同占空比条件下,重复频率越小温度周期变化越明显,振荡峰值越大,当占空比较小时随着辐照时间的增加重复频率对加热效率影响减小。     

低强度激光辐照HeLa细胞诱导增殖效应的可见光谱特性

比较研究了可见波段405,514,633和785nm低强度激光辐照HeLa细胞的促增殖效应。实验采用100和1 000J.m-2两种有效能量密度的可见光波辐照细胞,照射后24,48,72h采用MTT法检测细胞活性。结果表明,405,633,785nm激光均能促进HeLa细胞增殖,且呈波长和时间依赖性;633nm激光辐照对细胞促增殖效应最显著;514nm激光辐照对HeLa细胞促增殖效应较不明显。不同光剂量对细胞增殖效应不同,405,633,785nm激光辐照时能量密度为1 000J.m-2的辐照组细胞增殖均较100J.m-2辐照组明显,而514nm激光辐照时1 000J.m-2辐照组与100J.m-2辐照组细胞增殖的差异不明显。     

Optically pumped terahertz lasers with high pulse repetition frequency: theory and design

Optically pumped terahertz （THz） lasers with high pulse repetition frequency are designed. Such a laser includes two parts： the optically pumping laser and the THz laser. The structures of the laser are described and analyzed. The rate equations for the pulsed THz laser are given. The kinetic process and laser pulse waveform for this kind of laser are numerically calculated based on the theory of rate equations. The theoretical results give a helpful guide to the research of such lasers.