长春理工大学机电工程学院, 吉林 长春 130025
利用汉诺威弧焊质量分析仪、高速摄像机、光谱仪实现对激光-电弧复合焊接过程的焊接电信号、电弧形态图像、等离子体发射光谱等信号的同步采集。研究了激光-电弧两脉冲热源复合焊接过程中电弧形态变化、等离子体的电子温度和电子密度变化规律。结果表明, 电弧燃弧初期在激光匙孔和焊丝端部形成明显的抛物线形的白亮带, 白亮带成为电弧与熔池实现能量交换的主要通道, 随着电弧燃烧的进行白亮带逐渐消失。等离子体的电阻率的计算结果表明, 激光等离子体具有更低的电阻率, 是导电通道形成的始点。随着激光脉冲作用时间的增加, 等离子体辐射光谱的强度增加, 等离子体电子密度升高, 电子温度降低。
激光技术 激光-电弧复合焊 等离子体 光谱学 laser technique laser-arc hybrid welding plasma Spectroscopy
长春理工大学机电工程学院,吉林 长春 130022
以8.0 mm高氮钢板为试验材料,采用高速摄像系统观测熔滴过渡模式和电弧形态的变化,并采集焊接过程中电弧和熔滴图像。利用弧焊分析仪记录电弧电信号,通过试验深入研究了焊接过程中的熔滴过渡及电弧形态和电弧电压之间的关系。实验结果表明,在焊接电流 I＝160 A,电流电压 U＝22.4 V,其余焊接参数不变时发现,电弧形态变化所经历的时间长短有所不同,焊接电流越大,电弧形态变化时间较短。熔滴形成并长大的过程中电弧电压是逐渐减小的而对应的焊接电流增大,随着焊接电流的增大熔滴的过渡形式也会发生变化,熔滴尺寸减小,不同的熔滴过渡模式其电弧电压的波动也有所不同,射流过渡电压波动较小,而短路过渡电弧电压的波动最大。
熔滴过渡模式 电弧电压 电弧形态 droplet transfer mode arc voltage arc shape
1 南京信息工程大学 气象灾害省部共建教育部重点实验室, 南京 210044
2 中国科学院 安徽光学精密机械研究所 大气光学中心, 合肥 230031
3 国家知识产权局 专利审查协作中心, 北京 100190
大气温度廓线及其时间演变特征资料在地球科学领域具有重要的应用, 为获取高时空分辨的大气温度的垂直分布, 建立了瑞利-拉曼温度测量激光雷达。介绍了瑞利-拉曼激光雷达进行温度测量的主要原理和研制的瑞利-拉曼激光雷达的主要参数；数据处理方面, 通过背景噪声剔除和小波算法降噪提高系统的信噪比；使用研制的激光雷达对大气温度廓线进行观测, 将观测结果与大气模式数据和卫星观测结果进行对比, 均显示较好的一致性,证明了激光雷达温度测量结果的准确性, 其温度测量数据可以用于气象学研究。
瑞利-拉曼激光雷达 大气温度廓线 小波降噪 温度反演 Rayleigh-Raman lidar atmospheric temperature profile wavelet denoising temperature inversion
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039
A high energy all-solid-state blue laser with wavelength of 455 nm is proposed, which can be used in laser communication underwater or in the differential absorption lidar (DIAL) system. Ti:sapphire crystal is suitable material and is pumped by the second harmonic generation (SHG) of Nd:YAG laser. The pumped laser of 1000 mJ, 10 Hz is used, and the output wavelength of Ti:sapphire resonator cavity is controlled by external injection seeding. Parameters of the resonator cavity of Ti:sapphire crystal is carefully calculated and optimized. Pulsed 455-nm blue laser exceeding 100 mJ is obtained through frequency-doubled Ti:sapphire laser.
140.4780 Optical resonators 000.3870 Mathematics 200.0200 Optics in computing 190.2620 Harmonic generation and mixing Chinese Optics Letters
2007, 5(s1): 89
Author Affiliations
Abstract
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
An electro-optic Q-switched Nd:YAG ceramic laser operating at kHz repetition rate was demonstrated. Thermal induced lens' focus of ceramic rod was measured and compensated by plano-convex cavity structure. Depolarization loss at different output powers was measured in Nd:YAG single crystal and ceramic lasers. High-energy high-beam-quality laser pulse output was obtained in both laser structures. Pulse energy of about 20 mJ and pulse width of less than 12 ns were achieved, and the average power reached 20 W. The divergence of output laser beam was less than 1.2 mrad, and the beam propagation factor M2 was about 1.4.
140.3580 Lasers, solid-state 140.3540 Lasers, Q-switched 140.3480 Lasers, diode-pumped Chinese Optics Letters
2006, 4(4): 04219
