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脉冲激光由于具有峰值功率高、脉冲宽度窄等特点,在激光致声、激光焊接等领域中得到了广泛应用。使用特殊波形的脉冲激光,可获得比单脉冲高斯激光更加优异的应用效果,因此脉冲激光波形调节方法具有重要的应用价值。针对这一需求,提出并实验验证了一种基于分光延时的脉冲激光波形调节方法。首先对脉冲激光分光延时叠加原理进行了理论分析,设计出基于两次分光的四脉冲分光延时叠加光路,确定了产生矩形、三角形、驼峰形和双峰形脉冲激光所需的分光比与延时。然后搭建了一套基于Nd∶YAG脉冲激光器的二倍频532 nm激光的四脉冲分光延时叠加实验装置,成功获得了矩形、三角形、驼峰形和双峰形等特殊波形的脉冲激光。 相似文献
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介绍了厚膜电阻常用的喷砂微调和脉冲电压微调、激光微调三种微调技术及其发展趋势,重点介绍了激光微调机理、调阻方式以及微调图形分类。与喷砂和脉冲电压微调技术相比,激光微调具有精度高、速度快、效率高的特点,因而具有广阔的发展前景。 相似文献
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为研究飞秒激光脉冲对涡轮叶片材料的冲击打孔特性,使用双脉冲改写方程的激光光源项,并对涡轮叶片材料进行数值模拟,得到了镍基高温合金在飞秒激光双脉冲冲击打孔下的晶格和电子温度。通过对比单脉冲的模拟结果发现:双脉冲烧蚀情况下,材料电子和晶格出现2个峰值温度,且电子和晶格的平衡温度相比单脉冲提高345k,平衡时间延长了5ps,用 美国Ray Crop生产的飞秒脉冲激光器,对镍基高温合金材料在不同的激光参数下:激光脉冲宽度、激光能量、激光频率、脉冲间隔对材料的烧蚀进行双脉冲打孔,得到孔的形貌特征,并与单脉冲打孔对比发现双脉冲打孔的质量和效率优于单脉冲。 相似文献
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光镊已成为捕获和操纵微米尺度粒子和生物细胞的有效手段,而目前常用的光镊光源为连续激光或长脉宽的脉冲光。提出飞秒激光光镊的概念.将飞秒激光序列脉冲视为对连续光的周期抽样,借助于连续光光镊的分析方法,建立了飞秒激光光镊对电介质微粒产生的轴向光学力的理论模型。给出影响捕获微粒的主要因素,指出存在最佳束腰半径和被捕获粒子半径。数值计算结果表明选取合适的飞秒激光脉冲能量、束腰半径、脉冲波长以及微粒与周围媒质的相对折射率.微米尺寸的微粒完全能被飞秒激光稳定捕获。综合考虑被捕获微粒所受的脉冲式光学梯度力、重力和布朗惯性力的作用,讨论了飞秒激光光镊轴向光学梯度力的脉冲式特点及实现稳定捕获的条件。 相似文献
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原子或分子的光电离是强场物理效应的基础。在强场近似下,对于少周期激光脉冲,实验中已证实采用双色激光脉冲场可以增强和相干控制分子的电离。同时,双色场相对相位也是非常重要的参数,借助相位结构的改变来调节分子的电离亦是控制和优化激光与物质相互作用的重要方式。基于此,本文借助Lewenstein模型计算了双色激光脉冲场中利用CO分子高次谐波获得的阿秒脉冲,分析了不同分子取向下相对相位对分子电离以及产生阿秒脉冲的影响。结果显示,平台区域的超连续展宽在任意相对相位下均可产生,但随着分子取向和激光场相对相位的变化,电离较低时易获得超短孤立阿秒脉冲。 相似文献
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《激光杂志》1999,20(5):8
Different lines of TEA CO2 laser were
used to irradiate the vapours of dichlorodimethylsilane and chlorotrimethylsilane.Provided
the laser power densities were higher than the corresponding reaction-thresholds,the
vapour chemical reactions were able to be induced and SiC ultrafine powders were
synthesized.In the condition of the said experiments,the incident lines which coincided
with the absorption bands of the molecules caused chemical reactions via the mechanism of
multiphoton absorption,while the lines which were not sbsorbed directly by the molecules
in ground vibrational states caused chemical reactions via the mechanism of cascade
ionization.From the same material,the products made through the said two different
mechanisms were the same on the whole.And the higher laser power densities were helpful to
making purer ultrafine powders.So,the ranges of raw materials of these kinds of reactions
can be greatly expanded,and no more be limited by the photoabsorption of materials. 相似文献
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在飞秒脉冲激光的驱动下 ,使用泵浦 -探测技术测量了复合薄膜 Au- Ba- O的瞬态光学透过率随延迟时间的变化曲线 ,观察到了薄膜对光的吸收迅速增大并在皮秒时间内恢复原状的现象。该现象是薄膜中 Au超微粒子内费米能级附近电子被飞秒激光脉冲激发 ,产生非平衡态电子而经历瞬态弛豫造成的。从理论上给出了复合薄膜中 Au超微粒子的电子声子相互作用常数 g的数值 相似文献
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不同分散剂对超细镍粉分散性能的影响 总被引:1,自引:0,他引:1
通过测量直流电弧等离子体法制备的超细镍粉的Zeta电位,选取油酸(OA)、十二羟基硬脂酸(12HSA)、十二烷基苯磺酸钠(SDBS)、六偏磷酸钠(SHMP)、甲基丙烯酸甲酯(MMA)及司班-85(Span-85)作为分散剂,系统研究了六种分散剂在不同超声时间和不同分散剂浓度下,对超细镍粉的分散性能的影响。结果表明:随着超声时间和分散剂加入浓度的提高,粉体分散效果呈现先变好后变差趋势;推荐超细镍粉的最佳分散工艺为:添加质量分数3%的六偏磷酸钠进行分散,超声时间为25 min。 相似文献
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The topography, radial spread, and chemical composition of the slag produced during percussion and trepanning hole drilling
techniques using femtosecond laser were investigated. Results of analyses by optical microscopy, scanning electron microscopy,
and energy dispersion spectroscopy are presented. While there were no significant differences in the average ablation rates
observed when a near infrared femtosecond laser was used, when compared with the ultraviolet nanosecond laser ablation of
alumina (Al2O3) ceramics, that of the femtosecond laser provided much cleaner holes. There was an absence of particulates due to re-solidification
of molten material around the periphery of the hole. The slag consisted of ultrafine powders formed during condensation of
the supersaturated ablation plume. This slag can easily be removed in an ultrasonic bath with a mixture of acetone and water.
In combination with trepanning hole drilling, the femtosecond laser produced micro-via holes, in alumina wafers, that were
free of cracks and re-cast molten material. 相似文献