A 658-W VCSEL-pumped rod laser module with52.6% optical efficiency

A high-efficiency and high-power vertical-cavity surface-emitting laser(VCSEL) side-pumped rod Nd:YAG laser with temperature adaptability are demonstrated. The VCSEL side-pumped laser module is designed and optimized. Five VCSEL arrays are symmetrically located around the laser rod and a large size diffused reflection chamber is designed to ensure a uniform pump distribution. Furthermore, the absorbed pump power distribution of the rod is simulated to verify the uniformity of the pump absorption. Finally, a proof-of-principle experiment is performed in short linear cavity laser with single laser module. A continuous-wave output power of 658 W at 1064 nm is obtained, the corresponding optical-to-optical efficiency is 52.6%, and the power variations are ±0.7% over 400 s and ±3.1% over the temperature range from 16 ℃ to 26 ℃. To the best of our knowledge, this is the highest output power and the highest optical-to-optical efficiency ever reported for VCSEL pumped solid-state lasers. By inserting a telescopic module into the cavity and optimizing the TEM_(00) mode volume, the average beam quality is measured to be M~2= 1.34 under an output power of 102 W. The experimental results reveal that such a high power rod laser module with temperature stability is appropriate for field applications.

Analytical model for thermal lensing and spherical aberration in diode side-pumped Nd:YAG laser rod having Gaussian pump profile

In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.

Diode-pumped tunable laser with dual Cr：LiSAF rods

We propose and demonstrate a simple approach to lower the thermal quenching effect and improve the output power of Cr：LiSAF lasers, which is accomplished by employing two laser rods. The resonator contains two laser rods and is designed by using two ＂X＂ folding cavities in cascade. A tunable laser output of ～ 180 mW has been achieved with the pump of single-striped laser diodes. Compared with lasers using single gain rod, the laser with dual rods shows less severe thermal effect and increases the output by more than two times.

A 60 W Tm:YLF Laser with Triple Tm:YLF Rods

A narrow linewidth stable high-power continuous-wave 3.5% Tin3＋ doped LiYF4 （Tm：YLF） laser is reported. By using dual F P etalons and three Tm：YLF rods in a cavity, laser output of ~60 W at 1907.7nm is obtained with a slope efficiency of 34.8%. The M2 factor is found to be ~2.0 under an output power of 30 W. In addition, the relaxation oscillation and efficiency of the Tm：YLF laser are also studied. The relaxation oscillation of the Tm：YLF laser is improved obviously by setting the ratio of pump beam to oscillating laser beam as ~1.5：1 and the efficiency is increased in comparison with the ratio of ~1.3：1.

Improvement of 2.79-μm laser performance on laser diode side-pumped GYSGG/Er,Pr:GYSGG bonding rod with concave end-faces

A comparative study on the laser performance between bonding and non-bonding Er,Pr:GYSGG rods side-pumped by 970-nm laser diodes(LDs) is conducted for the thermal lensing compensation. The analyses of the thermal distribution and thermal focal length show that the bonding rod possesses a high cooling efficiency and weak thermal lensing effect compared with the conventional Er,Pr:GYSGG rod. Moreover, the laser characteristics of maximum output power, slope efficiency, and laser beam quality of the bonding rod with concave end-faces operated at 2.79 μm are improved under the high-repetition-rate operation. A maximum output power of 13.96 W is achieved at 150-Hz and 200-μs pulse width,corresponding to a slope efficiency of 17.7% and an electrical-to-optical efficiency of 12.9%. All results suggest that the combination of thermal bonding and concave end-face is a suitable structure for thermal lensing compensation.

A 4.8-W M^2 = 4.6 Continuous-Wave Intracavity Sum-Frequency Diode-Pumped Solid-State Yellow Laser

A yellow continuous wave with beam quality M^2= 4.6 and output power of 4.8 W at 589nm is generated by intracavity sum-frequency mixing of 1064 nm and 1319 nm radiations of a Nd：YAG laser. To achieve high beam quality at high power, thermally near-unstable flat-flat resonators with two-rod birefringence compensation are designed to obtain the large fundamental mode size inside the Nd：YAG rods and the same beam width inside the KTP crystal. The optimal intracavity power ratio of both 1064nm and 1319nm beams is also considered. The output power fluctuation of the yellow laser remains less than 5% in four hours.

航空薄壁枝杈类杆件激光选区熔化成形数值模拟研究

针对激光选区熔化成形航空细长、薄壁枝杈类结构杆件存在的翘曲变形问题,以航空发动机喷射杆件为研究对象,应用Simufact Additive仿真软件对该典型件的SLM成形过程进行数值模拟分析,验证了2种成形工艺方案下的零件在打印、基板分离、支撑去除过程中的残余应力分布与变形情况,探究了喷杆构件的最佳成形试制方案。结果表明:喷杆在竖直摆放成形时的变形量和残余应力值分别为0.26 mm和973 MPa,均小于45°放置成形的零件。根据支撑结构的设计结果,竖直摆放成形工件的支撑数量少,且容易去除,在有利于控制细长杆部变形、提高尺寸精度与表面质量的同时节约材料成本。

基于激光传感器的滤棒长度高速在线检测系统

为解决滤棒生产过程中,滤棒长度无法实时监控的问题,本文提出采用两台激光位移传感器的非接触式测量方式,建立滤棒长度的理论计算模型,设计由激光位移传感器、工控机、PLC、人机交互界面等组成的滤棒长度高速在线检测系统,实现了滤棒长度的在线检测、检测数据存储、不合格品剔除报警。测试结果表明:该系统实现滤棒长度的在线检测,检测精度为0.01mm;系统运行稳定可靠,操作简单易懂,人机交互性较好,对提高滤棒长度的在线监控水平、自动化程度和滤棒质量具有较好的实用价值。

基于车载激光扫描点云数据的杆状物提取方法

针对移动车载激光扫描点云数据中杆状物分类精度不理想的问题,本文从杆状物的空间形态特征出发,构建一种基于支持向量机(SVM)模型的杆状物分类算法。首先,根据杆状物空间形态特征确定10个特征值并建立特征矩阵;其次,进行SVM模型训练并建立分类模型;最后,使用训练好的最优SVM模型进行杆状物分类。选取某段城市道路的点云数据进行试验,结果表明,本文分类模型无须人工干预与阈值设定,自动化程度高,其中杆状物的最高分类精度能够达到94.23%。该算法具有有效性与优越性,可为基于激光点云数据的地物分类提供一定借鉴与参考。

High Peak Power, Single-polarized, Sub-nanoseconds Pulses Generation of a Yb-doped Rod-type Photonic Crystal Fiber Amplifier

We report a high-peak-power, single-polarized master oscillator power amplification system employing polarization- maintaining Yb-doped rod-type photonic crystal fiber. The MOPA system comprises of a Q-switched microchip laser generating ~630ps pulses at 8.6 kHz repetition-rate and two amplification stages employing double cladding fiber and rod-type PCF respectively. The MOPA system obtains narrow spectral bandwidth, single-polarized pulses of 9W maximum output average power, corresponding to peak power of 1.7MW.

A high-power high-stability Q-switched green laser with intracavity frequency doubling using a diode-pumped composite ceramic Nd:YAG laser

We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite ceramic Nd：YAG crystal is numerically analyzed and compared with that of conventional Nd：YAG crystal. By using a composite ceramic Nd：YAG rod and a type-II high gray track resistance KTP （HGTR-KTP） crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd：YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.

液压阻尼器活塞杆激光熔覆WC/Co06涂层耐磨耐腐蚀性能

目的研究WC添加量对WC/Co06复合涂层耐磨耐腐蚀性能影响,以期应用到液压阻尼器活塞杆表面,增强活塞杆耐磨耐腐蚀性能。方法采用同轴送粉式激光熔覆设备在液压阻尼器活塞杆用42Cr Mo钢表面制备不同WC含量(质量分数为5%、10%、15%、20%)的WC/Co06涂层,用金相显微镜、扫描电镜、X射线衍射仪及维氏硬度显微计,对4组不同WC含量的涂层进行质量检测。用滑动摩擦磨损试验机对涂层进行磨损性能测试。用盐雾腐蚀试验箱对涂层进行耐腐蚀测试。结果熔覆层表面质量良好,稀释率为5%左右。熔覆层显微组织随WC含量的升高越来越致密,WC/Co06涂层生成多种硬质相,如Cr_(23)C_(6)、Cr_(7)C_(3)、WC及Fe_(3)W_(3)C等分布在γ-Co固溶体周围增强其硬度以及耐磨耐腐蚀能力。4组熔覆层中,20%WC含量的熔覆层硬度最高(810HV),是基体的(275HV)2.95倍。摩擦磨损及盐雾腐蚀试验后,熔覆涂层磨损量及腐蚀失重均明显降低,其中20%WC熔覆层的磨损量及腐蚀失重最低,分别为基体的54.7%和21%。结论WC可提高熔覆层硬度,改善熔覆层的耐磨耐腐蚀性能,且WC含量越高,强化效果越明显。通过试验可得20%WC含量的WC/Co06涂层具有更优良的耐磨耐腐蚀性能。

紧凑高效型百瓦级2μm棒状Tm:YAG激光器

报道了一种结构紧凑、高效率、高功率的2μm棒状Tm∶YAG激光器。通过优化设计三向激光二极管(LD)侧面泵浦激光模块,提高了晶体棒内泵浦光的功率密度。激光谐振腔采用平平腔结构,包含单个激光模块,几何腔长为88 mm,整台激光器结构简单、紧凑且体积小。激光模块通过一个水冷机进行冷却,在冷却温度为12℃条件下,获得了最高功率为119 W、波长为2.02μm的激光输出,光-光转换效率为19.6%,斜率效率达32.7%。该激光器可在最大输出功率下连续稳定运转2 h,功率波动小于1%,晶体端面及光学元件表面不结霜。实验测得x和y方向的光束质量因子分别为21.01和21.68。这种紧凑、可靠、高效的百瓦级2μm激光器对于医疗和科学研究等应用具有重要意义。

高功率大能量窄脉宽全固态激光器研究进展(特邀)

高功率大能量窄脉宽的高峰值功率激光广泛应用于材料加工、科学研究等领域。综述了目前获得高功率大能量全固态超短脉冲激光输出的圆棒、板条、薄片放大器以及在半导体加工等领域极具应用前景的高功率大能量全固态调Q激光器国内外最新研究进展。

液压缸活塞杆激光熔覆再制造工艺模拟研究

以提高失效液压缸活塞杆激光熔覆再制造的质量、效率为研究目的,提出了逆向数据采集与激光熔覆路径规划相结合的再制造工艺方法。首先,通过对活塞杆失效形式分析,利用三维扫描数据采集、点云处理、数据逆向,得到了失效区域模型;然后,通过对激光熔覆路径规划、工艺参数设定;最终,得到了激光熔覆再制造工艺。结果表明:该方法能够有效对活塞杆进行再制造,技术、经济、环境方面具有可行性,该工艺能够达到甚至优于原品技术要求。

不同标记线制备方法对脊柱连接棒疲劳性能的影响

目的 研究不同标记线制备工艺对脊柱后路内固定系统连接棒疲劳性能和系统压缩疲劳性能的影响。方法 根据YY/T 0119.4—2014标准对脊柱连接棒进行4点弯曲疲劳测试。在一定应力作用下,依据YY/T 0857—2011对激光标记线连接棒和双色彩氧标记线连接棒进行系统压缩疲劳试验。结果 在715 MPa应力下,自制激光标记线连接棒和竞品厂家激光标记线连接棒疲劳寿命较无标记线连接棒分别下降了95%和98%;与未标记连接棒相比,激光标记连接棒疲劳强度由742 MPa下降至342 MPa,降低了54%。双色彩氧连接棒的疲劳寿命和疲劳强度与无标记线连接棒相当。双色彩氧连接棒系统压缩疲劳强度较激光标记连接棒提高约20%。结论 激光制备标记线显著降低了脊柱连接棒的疲劳性能和系统的压缩疲劳强度,改进的双色彩氧工艺制备标记线对连接棒的疲劳性能无影响,能有效降低临床断裂风险,为连接棒的性能改善和工艺开发提供参考。

改进PointNet++模型在道路杆状物提取中的应用

针对现有道路杆状物提取大多需要针对数据类型人工设计特征、泛用性差、自动化程度低等问题,本文提出一种基于改进PointNet++深度学习网络的道路杆状物语义分割方法,实现了对道路杆状物的提取。首先对原网络模型的感受野、分块大小等参数进行调整,使得该模型更适合道路点云数据;然后针对点云数据不平衡的问题,采用焦点损失函数作为模型的损失函数,使占比较少的类别得到充分训练;最后针对PointNet++网络提取特征时没有考虑邻域内各点特征影响关系的问题,采用邻域特征聚合模块融合邻域信息,提升该网络模型对点云特征的学习能力。为验证所提方法的有效性,使用改进后的网络模型在自建的道路点云组成的数据集上进行了试验,相对于经典PointNet++网络,杆状物类的分割精度明显提升,在简单道路和复杂道路上的交并比(IoU)分别提升了8.44%、15.25%,达到了98.88%、92.50%。

液压支架千斤顶激光熔覆再制造技术工艺实践

矿井环境复杂,粉尘颗粒、有害气体和潮湿等作业环境会对机械设备造成不同程度的腐蚀,同时因开采强度和开采深度的不断增加,引发的煤层硫化氢气体会加速损坏液压支架立柱及千斤顶的使用寿命。基于矿用液压支架千斤顶活塞杆在井下复杂的工况下出现不同程度的锈蚀、斑坑等表面局部缺陷,为有效解决活塞杆镀层损伤问题,提高部件复用率,黄陵矿业机电总厂通过对比分析,引进了一种先进的增材技术,即激光熔覆再制造技术,重点介绍了该技术的加工原理、修复工艺及特点等。实践表明,该技术显著提高了千斤顶表面的硬度、耐腐蚀性及耐磨性等性能,能够大幅延长液压支架千斤顶的服役寿命,保障矿井安全生产。

高线焊牌设备的设计与改进

在原有高线焊牌机器人的基础上,设计了一种带有拍照自检、铝牌激光打印功能的高速线材焊牌机器人,以解决标牌焊接成功无法判断,铝牌打印信息形式单一的问题,进一步提高设备的智能化程度,将工人从繁重的工作中解放出来。设备投用后,运行稳定,各项性能指标均满足要求,达到项目实施预期。

编码水准标尺检测的光电瞄准新方法

根据对编码水准标尺条纹图案的分布特征分析,并针对电子水准测量系统对标尺的精度要求,提出了一种多狭缝组合的光电显微镜瞄准检测标尺分划误差的方法。该方法中条纹图案由光学系统成像,并由前置多狭缝光阑的四象限光电池接收,光电池输出信号经处理后产生准确识别条纹中心的瞄准脉冲。该瞄准方法结合双频激光长度测量系统,可以实现编码标尺分划误差的动态检测,代替目前国内对编码水准标尺人工目视检测的过程。实验表明,该新型瞄准方法的瞄准精度优于2.0μm。