共查询到20条相似文献,搜索用时 125 毫秒
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采用控制环量方法设计了一单级涡轮。该方法打破了传统的设计规律,为验证该方法的可靠性进行了模型试验。在宽广的范围内测定了总特性;在设计点附近作了沿叶高效率分布及动叶进、出口速度三角形的测定。本文给出了主要试验结果并作了简要分析。结果表明基本上达到了设计要求,控制环量设计的主要特征得到了验证,该方法基本可行。 相似文献
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本文系统地讨论了大统一理论的来龙去脉。回顾了大统一理论的发展历史,讨论了其发展现状及存在问题,指出了进一步发展的方向。本文重点介绍了SU(5)和SO(10)两个模型,讨论了Higgs场、规范等级、渐近自由、重正化等问题。文章进而讨论了一些有趣问题,比如提供了对宇宙重子起源的解释、计算了质子衰变寿命、论述了B-L是否守恒以及讨论了中子和中微子可能有的振荡现象等。 相似文献
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体内(in Vivo)NMR研究 总被引:1,自引:1,他引:0
本文综述了体内(in Vivo)核磁共振波谱技术的目前概况,简要介绍了这一技术的基本原理。对空间定位技术进行了重点评述,并给出了分类表。同时讨论了化学位移对空间定位精确的影响,介绍了提高定位精确度的实验方法。列举了空间定位波谱技术在生命科学研究中的应用,给出了大量的参考文献。 相似文献
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用ICP-AES技术研究了胆石粉的处理过程,选择了合适的实验条件,并做了精密及回收率实验。为21例结石粉及其难溶部分进行了元素测定。计算了残留元素百分比,为医学研究提供了有用数据。 相似文献
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本文系统地讨论了大统一理论的来龙去脉。回顾了大统一理论的发展历史,讨论了其发展现状及存在问题,指出了进一步发展的方向。本文重点介绍了SU(5)和SO(10)两个模型,讨论了Higgs场、规范等级、渐近自由、重正化等问题。文章进而讨论了一些有趣问题,比如提供了对宇宙重子起源的解释、计算了质子衰变寿命、论述了B-L是否守恒以及讨论了中子和中微子可能有的振荡现象等。 相似文献
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We have studied the laser performance of Nd: KGW and Nd: YAG rods by monitoring the 1.06 μm laser emission at 78.5 K and 300 K. Our observations indicate that the laser efficiency from Nd: KGW is much higher than from Nd: YAG at these two temperatures. The laser threshold in Nd: KGW is lower at 78.5 K than at 300 K but it is always lower than that in Nd:YAG. 相似文献
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An eye-safe KTA OPO pumped by a Nd:YLF laser is demonstrated and a comparison with that pumped by a Nd:YVO4 laser is performed. Although the slope efficiency of the continuous-wave free-running Nd:YLF laser is lower than that of the Nd:YVO4 laser, the performance of KTA OPOs pumped by the Q-switched Nd:YLF laser is better, especially at lower repetition rates. The slope efficiency of KTA OPO pumped by a Nd:YLF laser is 14.6% at 30 kHz and 11.04% at 10 kHz. The better energy storage ability of Nd:YLF makes it an excellent laser medium in IOPOs. 相似文献
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Xiaofu Zhang Fangqin Li Runwu Peng Yuanfu Lu Qianjin Cui Yong Bo Qinjun Peng Dafu Cui Zuyan Xu 《Optics Communications》2009,282(9):1847-343
A compact high power diode-side-pumped Nd:GdVO4 laser has been presented, which can generate an output power of 52 W at 1.063-μm for continuous-wave (CW) operation. The absorption characteristics of the Nd:GdVO4 in different pump directions is measured, which were used to optimize the diode-side-pumped Nd:GdVO4 laser head. The laser characteristics of both CW and Q-switched Nd:GdVO4 and Nd:YAG in are compared and it was found that Nd:GdVO4 may surpass Nd:YAG for high power laser application. 相似文献
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We report for the first time a coherent radiation at 554.7 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser and 1341 nm Nd:YAP laser. Yellow-green laser is obtained by using a doubly folded cavity, type-II critical phase matching KTP crystal sum-frequency mixing. With total pump power of 36.1 W (17.8 W pump power for 1341 nm Nd:YAP laser and 18.3 W pump power for 946 nm Nd:YAG laser), TEM00 mode yellow-green laser at 554.7 nm of 1.43 W is obtained. 相似文献
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端面泵浦双Nd: YVO4激光器中热效应对腔稳定性的影响 总被引:7,自引:6,他引:1
利用多个激光晶体串接方式可以提高固体激光器的输出功率. 发展双Nd: YVO4晶体激光器, 将晶体的端面镀膜作为谐振腔的端面镜, 构成了平行平面谐振腔. 对平行平面谐振腔的等效腔进行了理论分析, 结果表明激光晶体吸收泵浦光产生的热透镜效应对保持腔的稳定性起到了重要的作用. 在国内首次进行了双端泵浦双Nd: YVO4激光器的实验研究, 在抽运功率为 20.74 W时获得了11 W的1064 nm TEM00模激光输出, 其光-光转化效率约为53%. 并且对于不同掺杂浓度下的实验结果进行了讨论. 相似文献
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High-power and high optical conversion efficiency diode-end-pumped laser with multi-segmented Nd:YAG/Nd:YVO_4 下载免费PDF全文
A novel flat-flat resonator consisting of two crystals(Nd:YAG + Nd:YVO_4) is established for power scaling in a diode-end-pumped solid-state laser. We systematically compare laser characteristics between multi-segmented(Nd:YAG + Nd:YVO_4) and conventional composite(Nd:YAG + Nd:YAG) crystals to demonstrate the feasibility of spectral line matching for output power scale-up in end-pumped lasers. A maximum continuous-wave output power of 79.2 W is reported at 1064 nm, with M_x~2= 4.82, M_y~2= 5.48, and a pumping power of 136 W in the multi-segmented crystals(Nd:YAG + Nd:YVO_4). Compared to conventional composite crystals(Nd:YAG + Nd:YAG), the optical-optical conversion efficiency of multi-segmented crystals(Nd:YAG + Nd:YVO4) from 808 nm to 1064 nm is enhanced from 30% to 58.8%,while the laser output sensitivity as affected by the diode-laser temperature is reduced from 55% to 9%. 相似文献
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We present for the first time a Nd:YAG laser emitting at 1319 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser.
A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at
1319 nm intracavity pumped at 946 nm. Intracavity sumfrequency mixing at 946 and 1319 nm was then realized in a LBO crystal
to reach the yellow range. We obtained a continuous-wave output power of 158 mW at 551 nm with a pump laser diode emitting
18.7 W at 809 nm. 相似文献
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We report for the first time a coherent radiation at 555 nm by intracavity sum-frequency generation of 946 nm Nd:YAG laser
and 1343 nm Nd:LuVO4 laser. Yellow-green laser is obtained by using a doubly folded cavity, type-II critical phase matching KTP crystal sum-frequency
mixing. With total pump power of 31.9 W (13.7 W pump power for 1343 nm Nd:LuVO4 laser and 18.2 W pump power for 946 nm Nd:YAG laser), TEM00 mode yellow-green laser at 555 nm of 2.35 W is obtained. 相似文献
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S. S. Zhang Q. P. Wang X. Y. Zhang Z. J. Liu W. J. Sun S. W. Wang 《Laser Physics》2009,19(12):2159-2162
A diode-end-pumped continuous-wave (CW) Nd:YAG laser emitting at 1123 nm is realized efficiently in a 25-mm-long cavity. A
composite Nd:YAG (cNd:YAG) crystal is selected as the gain medium. With an incident diode power of 26.1 W, an output power
of up to 9.3 W is obtained, corresponding to an optical-to-optical conversion efficiency of 35.6%. The laser performances
at 1123 nm are compared between composite Nd:YAG and common Nd:YAG crystals. The results show that composite Nd:YAG is a better
choice for 1123-nm laser generations. 相似文献