中低功率CO2激光切割非金属板材

介绍了CO2激光汽化切割非金属板材的机理,建立了理论模型,并根据材料的性质和切割速度预测切割深度。实验数据表明,该模型适合激光切割6mm以下的薄板。根据该模型可预测小功率激光切割非金属材料的能力,为提高切割速度,提出预热辅助气体的切割方法。     

有机玻璃激光气化切割前沿

以PMMA(有机玻璃)为试件,采用CCD拍摄到CO2激光气化切割前沿的照片。研究焦点位置、切割速度和激光功率对切割前沿形状和前沿深度的影响,并建立激光能量耦合模型。结果表明,由于前沿存在多次反射,使得切割深度增加。正离焦切割时,前沿吸收的总激光功率密度减小,切割深度减小;负离焦切割时,最大激光功率密度值的位置下移,使得前沿功率密度分布朝着深部推进,切割深度增加,若负离焦量过大,表面光斑直径和光程增加,更深位置的功率密度减小,切割深度减小;随着激光功率增加、切割速度减小,则前沿弯曲程度减小,被激光直接照射的前沿部位增长,前沿吸收激光功率密度增加,切割深度增加。     

紫外激光切割覆盖膜速度提升研究

文章针对基模激光束在切割运用中的特点,分别从激光频率,激光功率两个方面对紫外激光切割覆盖膜速度的影响条件进行研究,并进行相关的实验验证。同时运用我们的研究结果将39μm厚的覆盖膜切割速度由200 mm/s提升到350 mm/s。     

孔隙率对碳纤维增强复合材料光热辐射信号的影响

为了研究碳纤维增强复合材料(CFRP)孔隙率与光热辐射(PTR)信号的影响,建立了四层PTR理论模型,并搭建了相应的实验平台。采用三种不同直径的激光束分别对9种孔隙率的CFRP样品进行了实验,以玻璃碳为参考材料,对所得PTR幅值和相位信号进行了规格化处理。实验结果表明,在功率一致的条件下,相同调制频率下的PTR相位随着激光直径的减小而增加,而幅值刚好相反。激光束直径为0.2 mm时,低频率扫描的PTR相位信号随着孔隙率的增加而降低。     

高压输电线异物激光清除三维仿真研究

激光以其优异的性能在输电线路异物清除领域具有广阔的应用前景。为了安全、高效地清除输电线异物,须对激光与异物组织的作用机理进行研究。本文分析讨论了激光与尼龙材料的热作用机理,建立了激光束切割尼龙材料的三维数值仿真模型,仿真研究了不同激光移动速度和光斑尺寸下尼龙材料三维动态烧蚀形貌,分析研究了激光移动速度和光斑尺寸对材料烧蚀深度的影响趋势。结果表明,激光功率和光斑尺寸一定时,材料烧蚀的最高温度和烧蚀深度与激光移动速度成反比;激光功率和移动速度一定时,材料烧蚀的最高温度和烧蚀深度与光斑尺寸成反比。当激光功率为100W、光斑半径1cm时,烧蚀过程中不发生明火的激光最小移动速度为05cm/s。当激光移动速度为2cm/s、功率为100W 时,不发生明火的光斑最小直径为03cm。     

工艺参数对激光切割工艺质量的影响

对汽车用冷轧钢板进行了激光切割工艺试验,研究了激光切割速度与激光功率对切缝宽度、表面粗糙度、挂渣等切割质量的影响。结果显示在相同的条件下,切缝宽度随切割速度的增加而有一定的变化,随激光功率的增加而显著增加。切割速度及激光功率对切割表面粗糙度的影响是一抛物线规律,随切割速度的变化,切割边部形貌存在分形现象。金属材料激光切割后其热影响区非常小,受激光切割工艺参数的影响不大。     

基于355nm紫外激光切割柔性覆铜板的工艺参数优化

针对紫外激光切割柔性覆铜板时出现焦黑碳化、过熔及过多能量损耗等问题，采用355 nm紫外纳秒激光切割机对49μm厚聚酰亚胺双面无胶柔性覆铜板进行激光切割实验，通过预切割遍历参数以验证切割覆铜板的最小能量——临界切割能量。在此基础上，研究了切割参数对柔性覆铜板表面形貌、截面形貌、碳化程度、刻缝宽度以及表面和截面成分变化的影响。实验结果表明：激光切割速度、切割功率和重复切割次数对柔性覆铜板的切割质量具有重要影响，提升切割速度、保持适中的切割功率、降低重复切割次数能够获得切口光滑且无积碳的高质量、低功耗切割效果。由以上结果可得出本实验条件下的最佳工艺参数：切割速度为2000 mm/s，切割功率为12 W，重复切割次数为70次。本实验研究结果为实现柔性覆铜板的高质量、低能耗激光切割提供了工艺依据，而且该切割工艺可适用于柔性电路板、聚酰亚胺覆盖膜及补强板等通过激光切割成形的材料。     

激光切割锂电池负极极片复合材料的数值模拟

为了探究负极极片复合材料的切割性质, 采用有限元模型, 对激光切割锂离子电池负极极片复合材料温度场进行数值模拟计算。由温度场分布取得了负极切缝宽度与切缝深度的尺寸大小, 从中研究激光功率、切割速率和光斑半径对负极表层材料切缝宽度与切缝深度的影响。结果表明, 负极表层切缝宽度随激光功率和光斑半径的增加而增大, 随切割速率增大而减小; 切缝深度随激光功率增加而增大, 随切割速率和光斑半径增大而减小。切割至中间铜箔后, 切缝深度变化速率趋缓, 负极材料的复合结构对切缝深度存在明显影响; 在功率为170W、光斑半径为47μm、切割速率变化至600mm/s左右时, 效果最为明显, 切割深度在该参量下达到60μm, 且突破这一阈值后增长速率得到明显提升直至极片完全切断。这一结果可为激光应用于锂离子电池极片复合材料切割提供参考。     

电磁复合场驱动激光减材直接成型V型槽形貌研究

研究了电磁复合场对激光减材加工V型槽形貌的影响。在激光减材过程中同时施加稳态电场与稳态磁场,以获得定向洛伦兹力,从而驱动熔池排溢;通过实验研究了激光参数以及电磁场参数对V型槽形貌的影响规律。实验结果显示：在电磁复合场环境下通过改变激光参数得到了角度范围为34.82°～65.20°、深度范围为1719～5667μm的V型槽;角度随着激光功率的增加和扫描速度的降低而减小,深度随着激光功率的增加和扫描速度的降低而增大;当激光功率为1800 W时,随着磁感应强度从0 mT增大至1200 mT,V型槽底部的重熔层厚度从764μm下降至42μm;材料去除效率主要受激光功率的影响,并随着激光功率的增加而增大。加工出的目标V型槽的角度公差等级为精密（f）,深度线性公差等级为中等（m）,表面粗糙度Ra值为22.4μm。稳态磁场与稳态电场所提供的向上的洛伦兹力克服重力及表面张力驱动熔池向上流动,熔体以多次飞溅的形式脱离基体,实现一次直接成型V型槽。     

冻结陶瓷浆料激光扫描切割深度仿真与实验研究

基于冻结浆料的分层实体制造方法在多孔陶瓷3D打印领域具有应用潜力。为了研究冻结陶瓷浆料的激光切割过程，建立了CO₂激光面热源热传导数学模型，采用COMSOL有限元仿真模拟激光扫描加热过程，以纯冰为理想材料，结合实验研究建立激光切割深度数学模型。结果表明，冻结陶瓷浆料的激光切割过程与传统非金属材料相似，“V”字形的气化切割区深度随激光能量密度的增大而增大；由于陶瓷颗粒的吸热和散射作用，在冻结陶瓷浆料切割区下方存在热影响过渡区，实际切割深度与纯冰激光切割理论深度存在差异，在理论模型中引入材料特性相关修正系数后可较好地符合实际切割规律，为冻结陶瓷浆料激光切割工艺参数选择提供了参考。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.