基于零声子线泵浦的高效率Yb∶YAG薄片激光器

高功率激光器在工业应用领域的需求不断增长,提高光-光转化效率是降低其生产制造成本的关键途径。针对提高激光器光-光转化效率所面临的增益介质的热负荷问题,利用锁定波长的969 nm“零声子线”泵浦、自主研制的高性能Yb∶YAG薄片晶体和48冲程泵浦系统等,搭建了高效的连续Yb∶YAG薄片激光器系统,实现了最高输出功率373 W,光-光转化效率可达73.37%。其优异性能为后续开展千瓦级超快Yb∶YAG薄片激光器研究奠定了基础。

PE燃气阀门焊接工艺参数研究

针对聚乙烯(PE)燃气阀门的焊接质量问题,研制了PE燃气阀门自动热熔焊接设备。基于该焊接设备,以静液压强度为检验标准,采用正交试验以及单因素试验方法研究了翻边压力、翻边时间、吸热时间、焊接压力及保压时间等工艺参数对焊接性能的影响。结果表明,当翻边压力为0.17 MPa、翻边时间为61 s、吸热时间为110 s、保压时间为20 min时,利用自制热熔焊接设备焊接的PE燃气阀门的焊接质量最高,经80℃,4.0 MPa静液压试验检测,其耐压时间为1074 h,符合GB 15558.3–2008要求。

探究性学习呼唤服务型科学教师

<科学课程标准>明确提出"科学学习要以探究为核心.学生是探究的主体."探究既是科学学习的目标,又是科学学习的方式,亲身经历探究为主的学习活动是学生学习的主要途径.

Effects of Metal Absorber Thermal Conductivity on Clear Plastic Laser Transmission Welding

In our previous study, metals have been used as absorbers in the clear plastic laser transmission welding. The effects of metal thermal conductivity on the welding quality are investigated in the present work. Four metals with distinctly different thermal conductivities, i.e., titanium, nickel, molybdenum, and copper, are selected as light absorbers. The lap welding is conducted with an 808 nm diode laser and simulation experiments are also conducted. Nickel electroplating test is carried out to minimize the side-effects from different light absorptivities of different metals. The results show that the welding with an absorber of higher thermal conductivity can accommodate higher laser input power before smoking, which produces a wider and stronger welding seam.The positive role of the higher thermal conductivity can be attributed to the fact that a desirable thermal field distribution for the molecular diffusion and entanglement is produced from the case with a high thermal conductivity.

两微米激光无吸收剂焊接透明PET/纯白PP实验研究

透明和纯白热塑性塑料是激光透射焊接中最难焊接的两类塑料品种。为将透明聚对苯二甲酸乙二醇酯(PET)或纯白聚丙烯(PP)焊接在一起,利用这两种塑料在2μm波段具有适度透过率和吸收率的光学特性,使用自主研发的2μm光纤激光器在不添加任何吸收剂的情况下,分别对这两种塑料进行搭接焊,并将其与0.808μm激光采用添加吸收剂方法的焊接效果进行对比。结果表明,在无吸收剂的条件下,2.0μm激光可成功焊接透明PET和纯白PP,其样品的破坏拉伸力分别达到母材的57.8%和93.3%,且相对于0.808μm激光的焊接效果,2.0μm激光焊接得到的样品的力学性能较佳,外观较清洁、美观。

Stable noise-like pulse generation in all-PM mode-locked Tm-doped fiber laser based on NOLM

A stable noise-like(NL)mode-locked Tm-doped fiber laser(TDFL)relying on a nonlinear optical loop mirror(NOLM)was experimentally presented.Different from the previous NL mode-locked TDFL with NOLM,the entire polarization-maintaining(PM)fiber construction was utilized in our laser cavity,which makes the oscillator have a better resistance to environmental perturbations.The robust TDFL can deliver stable bound-state NL pulses with a pulse envelope tunable from〜14.1 ns to〜23.6 ns and maximum pulse energy of〜40.3 nj at a repetition rate of〜980.6 kHz.Meanwhile,the all-PM fiber laser shows good power stability[less than〜0.7%)and repeatability.

基于掺铥光纤激光器的体外碎石实验探究

采用线型腔结构,实现了中心波长为1939.31 nm、脉宽在0~2000μs可调、重复频率在0~2 kHz可调、最大平均输出功率为34.2 W的准连续掺铥光纤激光器,并利用此激光器在体外环境下开展结石消融量随激光脉宽与重复频率的变化规律的研究。结果显示:在相同时间内,当单脉冲能量相近时,增大脉冲重复频率(平均输出功率)有利于提高碎石速率;当平均输出功率接近时,单脉冲能量越大,石块消融量越大。在90 s的碎石时间内,石块经过31.8 W/0.053 J(250μs)、33.1 W/0.11 J(500μs)、33.5 W/0.22 J(1000μs)、34.2 W/0.45 J(2000μs)4组参数激光照射后的消融量分别为0.333,0.480,0.697,0.723 g,结石表面的最高水温分别为30.8,35.5,38.9,41.2℃。