激光辐照对不同饵料微藻生长的影响

利用Nd:YAG激光(波长1.06μm,功率5W,照射时间0.5-3min)和Ar 激光(波长:488nm,功率70mw,照射时间5-20min)分别照射角毛藻和叉鞭金藻,辐照后进行细胞增殖和生长速率的测定。实验结果表明:照射剂量为1min的Nd:YAG激光及剂量为5min的Ar 激光对叉鞭金藻有较明显的促长效果,这两种激光处理组的细胞增殖量在辐照后的两天内较对照组分别高42.9%和48.1%,但这种促长效果随时间的推移逐渐消失。不同剂量的两种激光辐照角毛藻后,在延滞期均出现生长抑制现象,但进入指数生长期或传代培养后,剂量为1min的Nd:YAG激光及剂量为10min的Ar 激光对角毛藻有明显的促长效果,其中在指数生长期1min剂量的Nd:YAG激光处理可促长27.0%,传代培养后10min的Ar 激光处理组生长速率提高达51.2%。本文对不同激光及不同激光参数条件下,两种饵料藻的耐受性及生长特性的差异也进行分析探讨。本实验结果不仅证实了已有研究的推论,还展示出激光技术在饵料藻种选育中的应用前景。     

原子印章YAG激光雕刻机的研究

本文阐述了原子印章ＹＡＧ脉冲激光雕刻机的工作原理，详细介绍了整机结构特点，以及激光器参数、工艺参数和计算机排版软件功能，并简述了激光进行原子印章雕刻时的作用机理，和激光特性参数、印章材料及计算机软件等因素对印章雕刻效果的相应影响。     

双波长Nd：YAG脉冲激光器的实验研究

根据多波长同时振荡条件，我们建立了大能量１０６４ｎｍ和１３１８ｎｍ同时运转的双波长脉冲Ｎｄ：ＹＡＧ激光器。得到了１０６４ｎｍ和１３１８ｎｍ的激光输出能量分别为０．５９４Ｊ和０．８６１Ｊ，效率分别为０．３１％和０．４５％。实验结果说明了该双波长激光器有较好的时间和空间重选性。     

YAG：Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

The sub-micron sized YAG ： Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.     

LD泵浦的Nd∶YAG腔内倍频激光器及其模式

用KTP晶体研制成LD泵浦的YAG腔内倍频激光器,得到0.532μm连续绿色线偏振激光输出,阈值泵浦功率为41mW,输出功率为1.4mW,斜效率为1.7％。研究了泵浦光对倍频激光横模的影响。     

Effect of Ca2+ and Mg2+ ions on the sintering and spectroscopic properties of cr-doped yttrium aluminum garnet ceramics

In this work, we investigated the effects of Ca²⁺ and Mg²⁺ ions and annealing temperature on the spectroscopic parameters of chromium-doped yttrium aluminum garnet ceramics (Cr:YAG). Samples were obtained with either a separate or a simultaneous addition of calcium and magnesium oxides. To achieve this, aqueous suspensions were prepared using Y₂O₃, Al₂O₃, Cr₂O₃, MgO, and CaO high-purity powders as raw materials. The obtained suspensions were freeze-granulated, pressed into pellets, debinded, and subjected to reactive sintering in vacuum at 1715°C for 6 h. Each material was annealed in air with temperatures between 1300 and 1700°C. Samples were also compared to Cr:YAG ceramics with the addition of silica as a sintering aid. All the materials obtained were then exposed to 445 nm excitation, and emission spectra in the visible and infrared wavelengths were recorded. The results showed that the emission spectra of Cr:YAG ceramics varied according to the annealing conditions: as-sintered samples exhibited strong emissions of around 680 nm and, after air annealing, of around 1400 nm. This phenomenon is attributed to the Cr³⁺→Cr⁴⁺ transition. Samples doped solely with MgO exhibited the highest emission intensity in the infrared region. Thus, Mg²⁺ ions provided the best conversion efficiency of chromium ions.     

Comparison of YAG: Eu phosphors synthesized by supercritical water in batch and continuous reactors

Luminescent yttrium aluminum garnet (YAG, Y₃Al₅O₁₂) nanoparticles doped with Eu (10 at%) were synthesized in batch-type and continuous-type supercritical water (SCW) reactors. In the case of the continuous-type SCW method, the particles of YAG: Eu phosphors were much smaller and demonstrated a uniform spherical-like shape. Inversely, in the case of the batch-type SCW method, a needle-like or elliptical-like shape was formed because a finite amount of time was required to reach SCW conditions from ambient conditions. However, the emission intensity of YAG: Eu phosphors synthesized by using the batch-type SCW method was stronger. Therefore, it is concluded that the continuous-type SCW method is superior to the batch-type SCW method from the viewpoint of the particle size and shape, but the luminescence property of phosphors in the continuous-type SCW method needs to be improved. In addition, a calcination process slightly improved the luminescence intensities of YAG: Eu phosphors generated by using either the batch-type or continuous-type SCW methods.     

YAG:Ce~(3+)荧光粉的制备工艺及发光性能研究

采用高温固相法制备了YAG:Ce~(3+)荧光粉,通过XRD、SEM和荧光光谱等对样品进行了分析。系统地研究了不同种类助熔剂、烧结温度、时间对YAG:Ce~(3+)荧光粉结构、形貌及发光性能的影响。通过调节助熔剂、烧结温度和时间等工艺参数,在不经过破碎、后处理工艺的条件下,制备出了形貌规则、粒度分布均匀、发光性能优良的YAG:Ce~(3+)荧光粉。研究发现在1600℃,保温5个小时,以BaF_2作为助熔剂的条件下,样品的形貌及发光性能均达到最好。     

不锈钢活性激光焊工艺研究

以不锈钢SUS304作为试验对象,分别研究了焊接速度、散焦离焦量、激光功率和保护气体等工艺参数以及活性剂和活性元素硫对不锈钢YAG激光焊焊缝成形的影响.试验结果表明,各焊缝表面成形良好,焊接速度和激光功率能明显影响焊缝成形,散焦离焦量和保护气体种类对YAG激光焊焊缝成形的影响较小.与硫含量较低的情况相比,活性剂和活性元素硫含量较高的情况下均能使得焊缝熔宽发生明显收缩,随着热输入量增加,活性剂增加熔深的效果也越明显,表明活性剂对熔深的影响效果与焊接过程的热输入量有密切联系.     

Influence of ZrO2 particles on the optical properties of pc-LEDs

Experimental and modeling progress and results aiming to increase the color uniformity of hemisphere-type pcW-LEDs are proposed. By adding micrometric zirconia particles, the light scattering is enhanced, that induces a decrease of phosphor necessary to obtain a specific CCT. The optical model is able to determine the optical properties (CCT, angular CCT distribution, chromaticity and packaging efficiency) in a hemisphere LED for various amount of YAG-phosphor and ZrO₂-zirconia particles. Based on previous process, the work is in the first step to fit the effective radius and refractive index that will be implemented in the optical model. In the second step, the optical model is compared with the experimental measurement to determine the absorption coefficient and conversion efficiency of a package of silicone resin containing phosphor and zirconia. Finally, the model, confirmed by selected experimental results, allows determining the optical properties of any king of package that lead to a CCT emission ranging from 4500 K to 6500 K. The analysis of these data is interpreted by comparing, for a specific CCT, the phosphor loss, the packaging efficiency and the angular distribution of CCT. The results show that if the effort is targeted on one of the previous parameters, there is always a counterpart on the other ones. Increasing the color uniformity will induce to decrease the packaging efficiency.