飞秒激光双光子微细加工技术及研究现状

飞秒激光双光子微细加工技术以其特有的高精度三维微加工优势,成为微型机械加工领域新的发展方向之一。介绍了飞秒激光双光子微细加工技术的原理和应用的现状。结合目前已有的微细加工技术,对双光子微细加工技术的特点加以评述。简要报道了利用飞秒激光双光子微细加工技术的一些研究进展。探讨了飞秒激光双光子微细加工技术今后的发展方向及其存在的基本问题。     

基于ANSYS的硬脆性材料脉冲激光打标温度场数值模拟

随着激光加工技术的发展,硬脆性材料的激光加工成为国内外研究的热点。建立了硬脆性材料3D有限元模型,采用扫掠法对模型进行了网格划分,选择高斯分布的激光光源为热源模型,实现了硬质合金和碳化硅脉冲激光打标过程的数值模拟,得到了这两种材料的温度场分布。     

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。     

脉冲激光与电化学复合的应力刻蚀加工质量研究

脉冲激光电化学复合加工可以有效去除激光辐照区域内的电解产物, 提高加工效率, 改善加工质量. 针对高性能金属材料的微细加工要求, 采用脉冲激光电化学复合的应力刻蚀加工方法对铝合金的刻蚀特性进行理论和试验研究. 通过比较激光直接刻蚀加工和激光电化学复合加工的特点, 应用扫描电子显微镜、光学轮廓仪等检测技术分析了刻蚀区域的形貌特征. 根据力学电化学原理, 探讨了金属材料微结构加工的应力去除机理. 通过加工试验, 研究了工艺参数和加工方式对加工质量的影响, 采用优化的工艺参数, 加工出了质量较好的微结构. 试验结果表明, 激光电化学复合的连续扫描加工稳定性好, 可以有效地降低表面粗糙度, 提高加工质量. 关键词： 激光电化学 应力刻蚀 加工质量 工艺参数     

第八届国际应用激光技术中国研讨会

激光作为一种先进的技术,正应用于各行各业。中国激光市场蕴含着巨大的潜力,激光应用市场不断扩大,激光加工领域不断开拓,除了纺织、服装等轻工业和汽车制造业、航空、动力和能源等重工业,正逐步向精细、微细加工集中,向电子制造业、集成电路行业、通信、机械微加工,     

用激光微细加工制作平面型InGaAs/InP PIN 光探测器

 采用激光微细加工技术来制作单片集成光接收机的探测器，在制作过程中，用固态杂质源10.6 μm激光诱导Zn扩散工艺来进行探测器的p-区掺杂。制作出平面型顶部入射的InGaAs/InP PIN 光探测器，响应度为0.21 A/W。分析了激光诱导扩散中影响探测器性能的因素，因此提出了扩散温度自动控制、扩散区温度分布均匀化及激光焦斑与扩散区精确对准等相应的改进方法。     

激光超衍射加工机理与研究进展

随着纳米科技和微纳电子器件的发展,制造业对微纳加工技术的要求越来越高.激光加工技术是一种绿色先进制造技术,具有巨大的发展潜力,己广泛应用于不同的制造领域.为实现低成本、高效率、大面积尤其是高精度的激光微纳加工制造,研究和发展激光超衍射加工技术具有十分重要的科学意义和应用价值.本文首先阐述了基于非线性效应的远场激光直写超衍射加工技术的原理与国内外发展状况,包括激光烧蚀加工技术、激光诱导改性加工技术和多光子光聚合加工技术等;然后介绍了几种基于倏逝波的近场激光超衍射加工技术,包括扫描近场光刻技术、表面等离子激元光刻技术等新型超衍射激光近场光刻技术的机理与研究进展;最后对激光超衍射加工中存在的问题及未来发展方向进行了讨论.     

多脉冲激光对K9玻璃的表面损伤实验研究

 实验研究了波长为1 064 nm、脉宽为10 ns、重复频率为1 Hz的激光脉冲对K9玻璃的表面损伤特点,给出了脉冲透过能量随激光脉冲作用次数变化的规律。采用3维立体显微镜对损伤形貌进行观察,发现K9玻璃的损伤表面呈环状分布,分为烧蚀区、微裂纹区和断裂区。随着激光脉冲个数的增加,损伤由点状破坏演变为损伤区,微裂纹逐渐增长,损伤面积逐渐增大。基于激光支持的爆轰波理论分析,激光与脆性材料的相互作用可引起微裂纹的大量增长。在多脉冲激光的作用下,K9玻璃损伤的累积效应明显,表面损伤阈值明显降低,表面裂纹增长明显,损伤面积逐渐增大;但随着激光脉冲的继续增加,这种损伤趋于稳定。     

激光加工技术

激光加工技术是一项集光、机电、材料及检测于一体的先进技术.激光具有的四大特性[1]:高的单色性、方向性、相干性和亮度性.应用激光固有的四大特性,将具有高能量密度的,能被聚焦到微小空间的激光用于加工的方法叫激光加工.激光加工主要涉及:激光焊接、激光切割、激光打标、激光雕刻等.     

陶瓷加工中的激光技术应用研究

工程陶瓷作为２１世纪的三大应用材料之一，其有效的加工方法已成为国内外专家学者探索的热点。而激光技术由于是非接触式加工，没有切削力，加工速度快，能加工一些特殊型面等优点，在陶瓷的加工方面得到了一定的应用，并取得了一定的进展。本文介绍了应用激光技术加工陶瓷和激光技术在陶瓷磨削中的辅助应用，并阐述了各种技术的基本原理和加工质量评价，同时展望各种激光技术在陶瓷加工中的发展趋势。尽早开发应用于陶瓷加工的各种激光新技术，对推动陶瓷的应用发展和激光技术的发展应用都有着深远的意义。     

Study of laser carving three-dimensional structures on ceramics: Quality controlling and mechanisms

Three-dimensional (3D) laser carving is a new, very flexible process and is very useful for machining the hard and/or brittle materials such as ceramics, carbide and hardened steel with high precision, excellent productivity and surface quality. In this paper, the effects of laser processing parameters on single-layer carving depth and surface quality are analyzed by laser carving on an Al₂O₃ ceramic with different processing parameters. The mechanisms of laser carving are also studied. A mathematical model of the relationship between the laser processing parameters and the laser carving depth is established, which is useful in obtaining the best machining parameters with the shortest time. Finally, a 3D pattern is successfully carved using the optimum parameters.     

基于CCD传感的激光粒度测试技术研究

颗粒测试在工业生产和科学研究中涉及的领域非常广泛,常用的颗粒粒度及其分布的测试方法是激光粒度测试法,其具有测试精度高、测量速度快、重复性好和可测粒径范围宽等突出优点。CCD传感器有灵敏度高、分辨率高、噪声小和较大的动态范围等优点,其作为激光粒度仪的探测器提高光强分辨率的应用已经很普遍了。为提高测量精度,通过对CCD传感技术的研究,应用图像处理的方法来设计光电探测器,搭建了基于米氏散射原理的激光粒度测试系统。实验结果表明,用CCD传感器采集光散射图像,再对图像进行处理,D50与D10误差在6%之内,D90误差在1%之内,降低了测量的重复误差。     

Precise etching of fused silica for refractive and diffractive micro-optical applications

One of the challenges of current laser material processing is the high-quality etching of transparent materials for micro-optical applications. The ablation of transparent materials with UV-, ultrashort pulse and even of VUV-lasers is characterized by a high etch rate and a high laser fluence and causes considerable surface roughness evolution. The combination of specific laser processing techniques, e.g., scanning contour mask technique and direct writing with a small laser spot, with laser-induced backside wet etching (LIBWE) allows the direct machining of dielectric materials with an almost optical quality for the fabrication of diffractive as well as refractive topographic features. The etching of multi-level elements, gratings with variable depth, micro-lenses as well as free-form surface topographies with PV-values from some 100 nm to a few micrometers, a nanometer depth accuracy and a low roughness of less than 10 nm rms is presented and demonstrates the capabilities of this approach for precision engineering.     

图像处理在光路自动准直系统中的应用

光路自动准直系统应用于惯性约束聚变的高功率激光装置中的光束自动调整。图像处理是光路自动准直的关键技术之一。针对神光Ⅲ原型装置,结合阈值化、重心法、中值滤波和圆拟合等多种不同的图像处理方法设计了一套合理的准直方案,并且在模拟实验平台上进行了实验验证。实验结果表明,光路自动准直系统能够在15min之内顺利完成光路的自动调整,光束近场调整精度优于近场光斑的±0.5%,光束远场调整精度≤±0.3″,满足了原型装置的总体要求。     

Shockwave and spallation in silver and other materials by sub-ns laser pulse at 1016 W/cm2 intensity

The laser spallation effect due to intense shockwaves caused by a brief and intense laser pulse irradiating a target surface, 2 mm thick, has been investigated for silver and other materials. For 300 ps IR laser pulse, at intensities of the order of 10¹⁶ W/cm², the shockwave may produce deformations of the back-face in ductile materials, such as Ag, Cu and Al. In heavy materials with high tensile strength, such as Ta, the shockwave produces cracks in the bottom of the laser crater but not deformation in the back-face, while in brittle materials, such as monocrystalline Ge, it produces only superficial cracks and flaking, but not deformation and spallation of the back-face. In thick polymeric materials, such as high-density polyethylene, the ablated crater shape is well defined and the shockwave is strongly damped, and no deformation has been observed in the back-face. The laser ablation yield and the ion acceleration in the backward direction have been measured by mass lost and time-of-flight measurements. SEM microscopy of the different irradiated targets, showing details of the crater size, edges, flaking and deformation in the back-face, useful for a discussion on the shockwave propagation and shock pressure calculation, is presented.     

微水射流导引激光打孔的传热分析

微水射流导引激光加工是一种热影响区小,具有高加工精度的新型技术.本文基于有限体积法建立了微水射流导引激光束对硅片打孔过程的传热模型,将打孔过程分为三个阶段模拟其间的热量传递、相变过程和相边界的移动;探索了微水射流导引双脉冲激光打孔过程,进行了双脉冲不同延迟时间下的传热过程的数值模拟,得到了最佳延迟时间.结果表明:在初始...     

飞秒激光加工蓝宝石超衍射纳米结构

蓝宝石具有超强硬度及耐腐蚀、耐高温、在紫外-红外波段具有良好的透光性等优点,在军工业以及医疗器械方面具有广泛的应用前景.然而这些优点又对蓝宝石的机械加工或化学腐蚀加工带来困难.飞秒激光脉冲具有热损伤小、加工分辨率高、材料选择广等特点,被广泛应用于固体材料改性和高精度三维微纳器件加工.本文提出了利用飞秒激光多光子吸收特性在蓝宝石表面实现超越光学衍射极限的精细加工.利用聚焦后的波长为343 nm的飞秒激光,配合高精密三维压电位移台,实现激光焦点和蓝宝石晶体的相对三维移动,在蓝宝石晶体衬底上进行精确扫描,得到了线宽约61 nm的纳米线,纳米线间的最小间距达到142 nm左右.利用等离子体模型解释了加工得到的纳米条纹的产生原因,研究了激光功率、扫描速度对加工分辨率的影响.最终本工作实现了超越光学衍射极限的加工精度,为实现利用飞秒激光对高硬度材料的微纳结构制备提供了参考.     

Pulsed TV-holography recording for vibration analysis applications

TV-holography is a well-known tool for vibration analysis. Using the so-called time-average method, this technique allows to record interferograms showing the mode shapes of a structure submitted to vibration excitation and is currently used for modal identification.Within the frames of a BRITE-EURAM program called vibration intensity processing using full-field multi-pulse laser technique (VIP), a TV-holography equipment has been developed, working with a 25 Hz pulsed laser and allowing easy on-site measurements. A measurement procedure has been defined and a specific data processing has been developed for the determination of structural intensity fields, which give transfer path of the vibration energy within a structure.The measurement of these quantities is possible the using classical means (accelerometers, stress gauges, etc.) but the data processing is complex and require a lot of accurate sensors because it is based on spatial derivatives of high order. The optical techniques (laser vibrometry, holography, etc.) are more suited for that purpose because of the high density of measuring points and because of the well-known advantages of these methods: reduced measurement time and no modification of the mass parameters of the structure as it is the case when using contact sensors.Different kinds of output data are then given: operational deflection shape, amplitude and phase, structural intensity field and its divergence through a further step of data processing. The complete procedure with the associated data processing has been tested (for various configurations of excitation and damping) first on a clamped plate, then on a cylinder and at the end on several industrial components.This paper describes the general measurement procedure and the equipment used. The data processing is also presented and various measurement results are shown. The conclusion gives the main advantages and limitations of the method and evaluates the application possibilities.     

漂移量反馈控制式激光准直方法

提出一种集光纤准直与光束漂移量反馈控制准直技术于一体的激光光束准直方法 ,它是在单模光纤对激光器出射光束漂移量进行初级准直的基础上 ,进一步对光束的漂移量进行反馈控制 ,进而提高出射光束的方向稳定性。准直系统中利用漂移量分离光路和光电检测系统对光束的平漂量和角漂量进行了分离检测 ,并各自构成相应的光束空间平漂量反馈控制系统和光束空间角漂量反馈控制系统 ,减小了平漂量和角漂量反馈控制中的相互耦合。引入单模光纤使激光器与光束漂移量反馈控制准直系统相隔离 ,减小了激光管热源温度变化等因素对准直系统的影响 ,同时还便于准直系统使用中的安装布置。上述方法的应用 ,提高了准直精度及准直效率。实验表明目前该方法准直精度可达 0 .7× 10 -7rad。