序列尖峰脉冲激光对铝板熔融热-力效应研究

 本文用金相显微和扫描电镜诊断技术，对序列尖峰脉冲准连续激光束辐照LY12CZ和LF6M铝合金板材，产生激光热熔融与激光热应力效应，使照射区板材引生激光烧蚀池和许多断裂裂纹，造成材料断裂破坏的机理，进行了研究。给出了激光热应力、裂纹扩展应力与照射激光强度的变化关系和研究结果。     

准分子激光的光束波面测量技术

 准分子激光在激光光刻和微细加工中有广泛的应用，要求激光具有好的稳定性和光束波面均匀性。介绍了准分子激光的波面特性以及波面分析测量技术。用波面分析仪对XeCl和ArF激光特性进行全面的测量和评估，给出了主要参数的测量结果，重点分析了光束均匀性。     

战场激光防护技术

分析了战场激光威胁。从激光防护的原理和技术途径出发，论述了激光防护的方法。介绍了几种典型的激光防护装置，并对激光防护技术的发展提出了几点看法。     

星载激光告警技术

随着激光武器技术的迅速发展，美、俄两国多次进行激光反卫星试验，卫星面临的激光威胁已日趋严重，进行星载激光告警技术研究势在必行。本文针对这项技术进行分析。     

时间分辨电子显微镜的可行性研究

文章从理论上分析了飞秒激光与金属阴极的相互作用过程．将飞秒激光与金属阴极产生的超短电子脉冲作为电子源，提出了一种具有时间分辨能力的电子显微镜(TREM)的概念设计．文章作者详细地研究了这种电子显微镜的可行性，并讨论了超短电子脉冲的传输和控制问题．     

激光等离子体喷射空间特性实验观测

用１．０５３μｍ的高功率激光辐照不同类型的柱形腔靶，采用空间成像技术分别获取激光注入孔、腔内和输运口等离子体喷射空间分辨图像，对激光等离子体喷射空间特性进行了实验观测。还采用了平面靶和特殊构形的转换体靶观测等离子体喷射行为。本文给出了实验中获得的典型结果，并对这些结果进行了简要的分析讨论。     

激光发明50周年的几点启示

2010年是激光发明50周年.文章首先回顾了50年前激光的发明,说明基础科学创新的重大引领作用.接着概述了50年来激光领域的重大进展,包括激光器技术及其应用研究的进展;举例说明了激光应用对基础科学的反馈和推动作用;归纳了高能激光器的几个发展趋势;分析了激光的军事应用及其科学技术支撑.最后给出了激光50年发展史的4点启示和今后的3类发展方向.     

激光大气等离子体光谱特性实验研究

报道了对波长为1．06μm的脉冲激光在气体样品中产生的等离子体进行光谱研究的结果。气体样品为一个标准大气压的纯氮、纯氧和空气，光谱探测范围为300～900nm。结果表明，各种气体样品的激光等离子体光谱均表现为连续谱和线状谱的叠加，文中分别给出了连续谱和线状谱的基本特征，讨论了这些特征与等离子体物理特性的关系，并分析了纯氮、纯氧与空气激光等离子体光谱之间的异同。给出了激光等离子体光谱的时间演化和空间分布的基本特征，并初步讨论了与这些特征相关的等离子体物理特性。这些结果有助于加深对激光等离子体特性和机理，特别是对等离子体产生后的弛豫过程和复合机制的了解。     

激光除漆技术及其在飞机蒙皮除漆工程化应用的研究进展

激光除漆技术具有无污染、无机械接触以及可实时监测等优势，有望成为飞机整机除漆的主要技术途径。对激光除漆技术的主要工作机理进行了分析。总结了工艺参数对除漆效果的影响规律，提出了工程化除漆中工艺参数的选定思路；并归纳了激光除漆效果评价方法。介绍了飞机蒙皮工程化激光除漆应用实例，并对激光除漆技术未来的研究重点进行了展望。     

高功率脉冲激光对阶跃折射率多模光纤损伤机理

 理论分析和模拟仿真研究了激光点火系统中光纤端面损伤、光纤初始输入段损伤和光纤内部损伤机理。结果显示：端面损伤主要是由光纤端面的杂质和缺陷引起；光纤初始输入段损伤是由光束的初次反射造成光纤局部激光能量密度增大引起的；光纤内部体损伤主要由于激光自聚焦效应引起损伤和光纤受到的意外应力产生微小碎片，吸收激光能量，引起光纤局部损伤。给出了激光点火系统中提高光纤损伤阈值的一般方法，主要包括光纤端面处理、设计合理的激光注入耦合装置。     

脉冲激光烧蚀推进技术的航天应用进展

脉冲激光烧蚀推进技术具有比冲高和推力可精确控制的特点,既可用于发射有效载荷也可用于星载动力,甚至可用小行星表面物质作为推进剂使其偏转轨道,因此,在航天领域得到越来越多关注。围绕激光单级入轨发射、同步轨道和火星轨道运输;激光微推力器用于航天器姿轨控,以及激光与电组合推进;激光烧蚀操控cm级空间碎片的轨道,以及激光烧蚀操控较大尺寸碎片的姿态;激光烧蚀偏转小行星轨道等方面,对脉冲激光烧蚀推进技术在航天领域研究现状和进展,进行了系统全面地归纳和总结,并对激光平均功率、波长、脉宽和推进剂选材等关键问题,进行了详细分析。     

Thrust enhancement via gel-type liquid confinement of laser ablation of solid metal propellant

Laser propulsion has been developed as a suitable small thruster technology for the attitude control of micro and nano class satellites. Laser-based thrusters meet the satellite design criteria for being of light weight and cost effective, because they do not require fuel storing and oxidizer for combustion. Also, thrust control by laser propulsion is achieved fairly easy. In this paper, we consider the confinement of plasma expansion by a gel-type liquid material, which results in the enhancement of the thrust for propulsion. We also present our attempts to resolve some known issues regarding laser ablation of solid and liquid targets. The level of thrust is quantified via the momentum coupling coefficient, which was experimentally measured using a ballistic pendulum system. We have discovered that the laser ablation confinement by the gel-type medium results in 2.3 times more enhanced driving force as compared to the water confinement. A proof of performance is demonstrated for using gel-type material for generating propulsion, and material characterization for optimal thrust performance is presented.     

Laser ablation of energetic polymer solutions: effect of viscosity and fluence on the splashing behavior

Laser plasma thrusters are a new kind of propulsion system for small satellites, and work with the thrust created by the laser ablation of a target. Liquid polymer solutions are very promising fuels for such systems, provided that no splashing of the target occurs, because ejection of droplets strongly decreases the performances of the system. We have investigated the nanosecond infrared laser ablation of glycidyl azide polymer solutions containing carbon nanoparticles as absorber. Shadowgraphy imaging revealed two cases, namely splashing regime and solid-like behavior. The transition between both regimes depends on the viscosity of the solution and on the laser fluence, and is explained by the recoil force acting on the target. Appropriate conditions to avoid splashing were identified, showing that this liquid polymer solution is a suitable fuel for laser plasma thrusters.     

激光推进冲量耦合系数的测量方法

 激光推进冲量耦合系数是激光推进的重要参数，反映激光能量转化为动能的能力。提出了水平双线支撑激光推进试验方法，推导了水平双线支撑激光推进时光船的运动方程和测量方程；通过高速相机测量位移，利用卡尔曼滤波计算速度的方法；解决了激光脉冲瞬间作用时速度随机起伏大和计算困难的问题。为水平激光推进冲量耦合系数的计算，提供了工程测量和计算方法。     

带延长圆柱形喷管激光推力器推进性能数值研究北大核心CSCD

针对抛物形喷管与圆柱形喷管相组合的带延长圆柱形喷管激光推力器模型,通过求解含激光能量源项的流体力学方程组,计算得到了不同单脉冲激光能量条件下3种构形参数对冲量耦合系数和推力的影响。结果显示带延长圆柱形喷管可获得高于600N/MW的冲量耦合系数,同时表明冲量耦合系数随圆柱喷管长度的增加而增大并趋于饱和,圆柱喷管饱和长度与激光能量呈线性关系。冲量耦合系数随抛物形喷管张角的增大先增大后减小,对于总长度为100mm的喷管,半张角在33°左右时取得最大值且受激光能量的影响很小。冲量耦合系数随点火位置的增大也存在最大值,最大值对应的点火位置与激光能量成线性关系。     

激光推进流场演化的高速阴影测量方法

 介绍了高速阴影技术在激光推进流场演化诊断过程中的应用。采用了阴影技术和高速摄影相结合的方法，对激光推进流场演化过程进行了考察。由高速相机提供时序零时，控制激光器和闪光源的延迟时间，再对高速相机进行同步曝光，解决了高速阴影测量过程中高速相机、闪光仪和激光器的时序控制问题，实验获得了清晰的流场演化图像，为进一步研究提供了实验依据和便利条件。     

Investigation of laser via formation technology for the manufacturing of high density substrates

Fabrication of micro-vias is one of the critical processes in manufacturing high-density printed circuit boards. The conventional mechanical drilling technique becomes expensive for vias smaller than 200 μm in diameter due to the frequent breakage of the drill bits and machine downtime. The inability to produce blind vias renders the mechanical drilling method of limited use in providing vertical interconnections needed for multi-layer boards. Laser micro-drilling has emerged as one of the most feasible technologies for forming micro-vias. It offers greater resolution over the mechanical technique and is capable of producing vias well below 70 μm, consistently. The feasibility of being able to laser drill depends on the laser characteristics such as wavelength, energy density and pulse shape of the laser beam on the one hand, and on the type, structure configuration and thickness of the PCB substrate on the other hand. As most of the PCB materials have finite absorption characteristics with respect to the laser wavelength, only certain laser types are compatible with the common substrate materials. Laser via-drilling can either be a serial process with one via drilled at a time, or a mask imaging process with many vias drilled simultaneously. In this paper, the issues involved in the laser micro-drilling of PCB vias, including beam characteristics and processing mechanisms, for different substrates are investigated. A brief comparison with the other two emerging technologies, i.e. photo-vias and plasma etching is also discussed.     

生物医学领域中超连续激光光谱技术的研究进展

超连续谱激光指的是当泵浦激光穿过特殊光波导时,一系列的非线性效应引起入射激光束的光谱展宽,从而输出宽光谱激光束。随着超快激光和光子晶体光纤技术的发展,利用超短脉冲在光子晶体光纤中的传播链产生相干的且亮度高的超连续谱激光成为了一种理想的白光源。自从超连续谱激光源投入应用以来,其应用领域越来越广。尤其在生物医学的细胞、血液等样品分析当中,荧光光谱学、流式细胞仪、共焦显微、光学相干层析等技术都是强有力的分析工具,在采用这些先进技术的科学仪器中,超连续谱激光源成为了一种主要光学部件。首先对超连续谱激光源的国际研究进展作了详细介绍,然后对超连续激光光谱技术在显微成像、流式细胞仪、荧光寿命成像显微、荧光共振能量转移、光学相干层析、共焦显微生物医学分析等生物医学领域中的发展及应用作了综合阐述。对超连续激光光谱技术在非接触式血液制品鉴别的需求、方案及研究进展进行了重点论述,包括覆盖400~2 000nm光谱范围的光纤化轻型超连续谱激光光源研究;采用超连续谱激光光谱方法探索不同物种血液的种属特征;根据大数据的血液样品光谱特征元数据库分析建立数学模型,利用数学模型实现对血液样品种属光谱学判定;血液鉴别光谱分析便携式整机系统研发等。对超连续激光光谱技术在生物医学领域的应用前景作了展望。     

“烧蚀模式”激光推进技术及其应用研究

随着激光技术的发展，激光推进技术越来越受到关注.“烧蚀模式”激光推进是激光推进技术中一个重要的研究领域.本文在介绍了“烧蚀模式”激光推进的原理、研究现状和几个亟待解决的热点研究问题的基础上，对激光推进的进一步应用进行了探索与研究.     

The ALP-PALS project: optimal coupling for laser propulsion

Ablative laser propulsion (ALP) could revolutionize space travel by reducing the 30:1 propellant/payload ratio needed for near-earth orbit 50-fold. Experiments to date have demonstrated the necessary efficiency, coupling coefficient, and specific impulse for application, but were performed at pulse energies and spot sizes much smaller than required and at wavelengths not usable in the atmosphere. Prior experiments have also not simultaneously measured the properties of the ions produced or of the ablated surface, properties that would allow full understanding of the propulsion properties in terms of ion characteristics.

The first realistic measurements of laser propulsion parameters are proposed using PALS (Prague Asterix Laser System), the important parameters of which (pulse energy (～ 1 kJ), pulse length (400 ps), beam diameter (～ 29 cm), and flat beam profile) equal those required for application. The PALS wavelength is a little short (1.3 μ m vs.>1.5 μ m) but is closer than any other laser available and PALS’ 2ω/3ω capability should allow extrapolation to application values. The PALS’ proven infrastructure for measuring laser-driven ion properties means that only a ballistic pendulum for measuring momentum transfer will have to be added.