Feasibility of the 248 nm Excimer laser in the laser structuring of fine circuit lines on printed circuit board

Excimer laser (KrF) is used as a new laser source to determine its feasibility in the laser structuring process. Compared with frequency-tripled Nd:YAG lasers, the Excimer laser can conveniently change the spot size of a laser beam to get a smaller sized circuit line/space by inserting a mask. Some frequently used laser parameters of the Excimer laser are discussed in this paper, such as laser energy, number of repetition, repetition rate, bite size and laser beam size. The differences between the Nd:YAG laser and the Excimer laser in laser structuring are also explored in this paper.     

基于ZEMAX的激光光束整形技术试验研究

由于半导体激光器的发散角较大且输出的光束光斑是椭圆形,因此需要对其输出的光束进行空间整形,形成一个近似圆形的激光光斑。激光扩束镜就是一种比较简单且非常方便的激光光束整形器件,本文将激光扩束镜作为一个激光整形系统与半导体激光器耦合,形成一个完整的激光光束整形系统。利用ZEMAX光学仿真,并进行室外试验验证,最后对试验结果进行了分析。     

用于纳秒级窄脉冲工作的大功率半导体激光器模块

介绍了一种将脉冲半导体激光器发射应用系统中脉冲整形电路、驱动电路、激光器保护电路、激光器集成封装成一个激光器模块的方式。当激光器工作于纳秒级窄脉冲状态下时,激光器封装引腿所产生电抗会使得耦合进激光器的脉冲波形劣化,能量损失。为得到上升时间短,波形半宽窄,峰值功率大的光输出,改进激光器管芯的结构并采用混合光电子集成的方式将驱动电路和激光器管芯封装在一个模块内,使得窄脉冲电信号高效地耦合进半导体管芯。分析验证了改进后的激光器模块的各项输出参数均得到改善。同等条件下,改进后的模块在光脉冲宽度为4.5ns时,峰值功率比单独封装激光器提高6倍多。此激光器模块可以得到宽度7ns左右,峰值光功率176W的光脉冲输出。测试了该模块在脉冲宽度为7ns左右的U-P曲线。     

Influence of laser heat treatment on microstructure and properties of surface layer of Waspaloy aimed for laser-assisted machining

In this study, a nickel-based superalloy, Waspaloy, was laser heat treated with diode laser. Single laser tracks were manufactured with different laser beam power densities between 63 and 331 kW/cm², and scanning laser beam speed ranged from 5 to 100 m/min. It was found that laser heat treatment of Waspaloy causes decrease in material hardness—the microhardness in laser tracks is about 300 HV0,1 while the microhardness of substrate is ranged from 300 to 600 HV0,1—which is a positive phenomenon for laser-assisted machining of investigated material. Impacts of laser heat treatment parameters on laser tracks properties were identified for obtaining multiple laser tracks with the most homogenous thickness. Moreover, roughness of heated layers was measured to specify surface quality after laser heat treatment. Multiple laser tracks were produced using different scanning laser beam speed and distances between laser tracks ranged from 0.125 to 1 mm. It was found that if scanning laser beam speed is 75 m/min and distance between laser tracks is equal to or lower than 0.25 mm, in microstructures of multiple laser tracks, cracks are occurring. The most suitable laser heat parameters for obtaining heated layers, and which can be used for laser-assisted machining, were identified as laser beam power density 178.3 kW/cm², scanning laser beam speed 5 m/min, and distance between laser tracks 0.125 mm.     

Improvement and validity of shock measurements using heterodyne laser interferometer

The improvement and validity of shock measurements using only the laser head (heterodyne laser interferometer) of a commercial laser Doppler vibrometer was investigated by comparing acceleration waveforms measured by a homodyne laser interferometer with those measured by a heterodyne laser interferometer. The acceleration waveforms were generated from the displacement waveforms obtained with a reference quadrature homodyne laser interferometer by applying a numeric differentiation process twice. The differences between the two acceleration waveforms were found to be small with the measurement uncertainty in case of high acceleration level. In a further investigation, the accuracy of the shock measurements taken by the homodyne and heterodyne laser interferometers were compared in computational simulation. The results indicated that the accuracy of the heterodyne laser interferometer was superior to that of the homodyne laser interferometer.     

引信激光装定用脉冲半导体激光器电源设计

在引信激光装定系统中，针对引信装定信息时脉冲半导体激光器，电源激光频率可调（PFM）、功率可调（PPM）的要求，结合半导体激光器的工作特性，设计一种以单片机（MCU）为控制芯片，以晶体三极管与场效应管为窄脉冲驱动电路的大功率半导体激光器电源。同时为电源驱动电路设计了DC-DC变换器。其中，激光频率设置为连续可调，激光器的驱动电流6～30A连续可调。该电源已应用于引信激光装定系统中，通过仿真与实验验证，该激光器电源工作正常、性能稳定。     

激光作用下纳米SiC陶瓷材料制备研究进展

综述了基于激光能源的纳米SiC陶瓷材料制备研究现状,包括零维纳米SiC离子、一维纳米SiC晶须、二维纳米SiC薄膜和涂层以及三维纳米SiC块体等的制备;介绍了相关的各种激光制备方法如激光诱导气相沉积法、激光熔覆法、激光消融法、激光退火法和激光重熔法等,并对其发展前景作出展望。     

Focusing quality of a split short laser pulse

For multiple laser pulse experiments, it is necessary to split a laser pulse. In order to split a short laser pulse without stretching the pulse width, the laser pulse should not pass through thick materials. For this reason, a pellicle beam splitter (BS) and/or a mirror with a hole are required as a BS for the short laser pulse. The focusing qualities of the laser pulse after passing through the pellicle BS and the mirror with a hole are the same as without the BS's. The laser pulse quality reflected by the BSs should be considered for the laser pulse. A pellicle BS is a thin foil, so, it is weak against vibrations. One should be careful about airflows and isolation from vibration sources. The spot size of the reflected laser pulse is consistent with the size reflected by a normal mirror. The energy loss is about 10% compared with a normal mirror. A mirror with a hole is strong against external vibrations. The reflected laser pulse has a doughnut shape. The reflected laser pulse is interfered due to the shape. In order to cleanly focus the laser pulse, the inside size of the doughnut should be smaller than a half size of the outside portion of the doughnut.     

基于光辐射压力的激光功率测量技术

随着激光应用领域的快速拓展,超高峰值功率、超窄脉宽逐渐成为未来激光行业的重点研究方向之一,这种激光的超高电场能量给高精度的激光功率测量提出了挑战。传统的激光功率测量方法,如光电法、热释电法、量热法等逐渐显露出不适用于上述激光功率测量的缺点,此外上述方法都难以实现实时、在线测量。为了克服以上困难,需要一种新型激光功率测量原理与方法。以美国国家标准与技术研究院为代表的机构提出了一种光辐射压力测量法,该方法使激光作用在高反射率的反射镜上,激光动量形成了光辐射压力,这个力可以采用多种力学传感方式进行计量。该方法不但能实现激光功率快速、准确测量,而且不影响激光能量传输,可以实现实时、在线的激光功率测量。系统回顾了国内外通过光辐射压力测量激光功率的基本原理和系统组成,光辐射压力测量激光功率的研究现状,并对该方法的发展方向进行了展望。     

基于半导体激光光纤组件的激光准直仪

介绍一种基于半导体激光光纤组件的激光准直仪 ,讨论了使用角锥棱镜作为活动靶镜的测量原理 ,给出了准直仪的软硬件设计方案。通过各种实验表明 ,本准直仪可直接应用于工业测量。     

染料调Q的Nd3+∶YAG激光器偏振性测试

为了确定染料调Q的Nd3+:YAG激光器发射的单次激光脉冲的偏振性,利用偏振分束立方体和双通道激光能量计,实验测量了激光脉冲经偏振分束后P偏振光和S偏振光的能量比,分析总结了激光器的偏振性.结果表明:激光器偏振性个体差异很大,不存在统一性;每一台激光器都有各自的偏振性,同一台激光器前后发射的激光脉冲的偏振性可能一致,也...     

砷化镓光伏电池的激光光照特性研究

激光无线能量传输技术具有广阔的应用前景,而光伏电池的激光辐照特性是设计激光无线能量传输系统的重要依据。针对该问题,研究了激光功率与温度对光伏电池的影响,搭建了光伏电池激光辐照特性的实验测试平台,测量并分析了光伏电池输出特性随激光强度和电池温度的变化规律。结果表明,激光辐照条件下,激光强度一定时,短路电流随温度升高而降低;温度一定时,转换效率与填充因子随激光强度的增大呈现先增大后减小的趋势。该研究可为激光无线能量传输条件下的系统设计仿真以及激光辐照下光电电池的输出特性研究提供参考。     

准分子激光脉冲直写刻蚀速率与能量密度的关系

为了探索低成本、大深宽比加工方法,建立了实用的准分子激光微加工系统.以玻璃为实验靶材,用精密微动平台准确调节靶材位置,利用波长248nm的KrF准分子激光器,研究了准分子激光直写刻蚀过程中平均刻蚀速率与激光脉冲能量密度之间的关系.加工出的沟槽剖面形状均呈现锥型,单脉冲烧蚀速率随脉冲数的增加而减小,激光脉冲对材料的刻蚀具有能量阈值,加工槽的深度具有上限值.采用平行激光束或对加工过程进行动态控制还可实现矩形深槽或圆柱深孔的加工.     

激光喷丸强化系统协调控制方法与实现

针对复杂型面工件激光喷丸强化应用中对加工点位精度的要求以及激光脉冲触发时间点需要与工业机器人调姿到位时间点精确匹配,提出激光脉冲与工业机器人协调控制方法。通过脉冲能量检测实现出光快速反馈,并基于EKI接口通讯实现KUKA机器人运动控制及到位反馈,完成激光脉冲与工业机器人点位运动闭环匹配。在此基础上研制激光喷丸强化工艺系统,主要包含激光光源、工业机器人、传输光路、工艺辅助模块以及上位机控制平台。以平面点阵坐标进行协调控制实验及对整体叶盘进行激光喷丸强化实验。结果表明,本系统具备较好的激光脉冲-工业机器人协调控制精度,能自动完成激光喷丸强化工艺流程,具有对复杂型面工件的激光喷丸强化能力。     

Principles of designing adaptive relay systems for stratospheric power transmission

Problems of designing laser power transmission systems in a turbulent atmosphere using relay mirrors mounted on a stratospheric airship are analyzed. It is shown that such a system can be designed using a high-power ground-based ytterbium fiber laser, relay mirrors for transmitting highpower laser radiation, and an adaptive optical system for correcting the phase distortions of laser beams due to atmospheric turbulence. A model of a laser power transmission system was designed and tested under laboratory conditions; the tests confirmed the possibility of correcting atmospheric-turbulence distortions during guiding and high-accuracy stabilization of laser beams.     

A gas-discharge He–Ne laser generating monochromatic radiation with λ = 1.52 μm for testing telecommunication systems

The results of a detailed study of a gas-discharge He–Ne laser that generates monochromatic radiation with λ = 1.52 μm are presented. Such important laser parameters as the divergence of laser radiation, the laser power as a function of the temperature, the laser-power stability, and noise and spectral characteristics of radiation were measured. The attained parameters of laser radiation in the aggregate occurred to be virtually ideal for using the laser in tests of telecommunication systems. The possibility of laser microminiaturization is shown, which is of interest when using it under the conditions of a high level of electromagnetic noise.     

激光焊接技术的研究现状与应用

激光焊接是激光加工材料加工技术应用的重要方面之一。以美国、欧盟、日本为首的工业发达国家非常重视激光技术的发展与应用,都将激光技术列入国家发展计划中,投以巨资。目前激光焊应用领域主要有：制造业、粉末冶金、汽车工业、电子工业、生物医学、航空航天工业、造船工业等。本文对激光焊接技术的概况、国内外激光焊接技术的研究现状、激光焊接技术的应用、激光焊接技术的发展趋势等方面进行了综述。希望对激光焊接技术的研究现状与应用有一个比较全面的了解。     

激光技术在汽车工业上的应用

激光加工在制造和表面强化上的应用已经有多年的历史.激光加工技术在汽车上的应用具有很大的经济价值,但我国激光技术在汽车上的应用还很不广泛,尤其是激光拼焊板.文中基于激光拼焊、激光复合焊、激光熔铸、激光淬火和激光快速制造的介绍来说明激光技术在汽车上的应用具有非常广阔的前景.     

Gas-discharge He–Ne laser with a wavelength of 1.52 <Emphasis Type="Italic">µ</Emphasis>m for telecommunications systems

Results of a detailed study of a gas-discharge He–Ne laser with a wavelength of 1.52 µm for telecommunications systems are reported. Some important parameters of the laser are measured, such as the laser beam divergence (M ²), the laser power as a function of temperature, laser power stability, noise characteristics of laser radiation, etc. A possibility of laser microminiaturization is mentioned, which is of interest for its application under conditions of intense electromagnetic interference.     

基于激光莫尔信号精密定位装置的精度提高

为提高基于激光莫尔信号精密装置的定位精度 ,本文探讨了激光束束径与激光莫尔信号的依存关系 ,给出了与光栅衍射缝隙条数相对应的最小激光束束径的大小。其次还说明了激光源的光强度变化对精密定位装置的定位精度影响