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在原子衰减常数相等、单光子失谐不太大且饱和不太深的条件下,对于两个适当的原子-场耦合常数,简并双光子激光系统一方面能够呈现无反转激光,另一方面又能够呈现无激光反转。
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从激光推进的要求出发,阐述了用于激光推进的高功率激光器的选择原则,即激光器必须满足:(1)高的平均功率和峰值功率;(2)高的单脉冲能量;(3)高的重复频率;(4)优良的大气传输特性。主要分析了目前YAG固体激光器、自由电子激光器和TEA脉冲CO2激光器的特点,通过上述4个方面性能的比较,认为在目前水平下,TEA脉冲CO2激光器是进行激光推进的首选强激光源,其优点表现在:功率可达10kW量级,单脉冲能量可达0.5~1kJ,重复频率为20~40Hz;激光波长处于大气传输窗口,对大气变化不敏感;工作物质快速流动,不存在热透镜效应和破坏阈值;相关光学元件易于制造;光束质量较好;运行成本低。 相似文献
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A.?A.?Ionin Yu.?M.?Klimachev A.?Yu.?Kozlov A.?A.?Kotkov O.?A.?Romanovskii L.?V.?Seleznev D.?V.?Sinitsyn O.?V.?Kharchenko
In the present work it is demonstrated that a wideband CO laser operating at fundamental and overtone vibrational transitions
is a promising source of laser radiation for remote laser sensing of the atmosphere. A compact slab RF-discharge CO laser
has been designed. The optimal operating conditions are determined for this CO laser. In experiments, the maximum average
output laser power was ∼12 W for lasing efficiency of ∼14%. Under fixed experimental conditions, stable lasing (with fluctuations
of the output laser characteristics ≤5%) was observed during more than one hour, which suggests that we first excited the
sealed-off mode of cryogenic slab RF-discharge CO laser. The frequency-selective mode was first obtained for this laser. Wavelengths
for sensing of nitrous oxide, nitrogen dioxide, methane, formaldehyde, and some other gases on near-ground propagation paths
are determined. Our experiments and calculations confirm that this CO laser is promising for laser gas analysis.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 76–83, November, 2008. 相似文献
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为了提高激光无铅钎焊的速度,对影响激光无铅钎焊速度的因素(如激光的参数、所用钎料和基体的特性、钎焊的系统结构等)进行了分析研究。研究认为,在激光器、钎料及基体等已定的情况下,相对于那些受到机械惯性制约的移动激光加工头或移动工作台的激光钎焊系统,一种配备了振镜扫描系统和f-theta聚焦透镜的激光钎焊系统具有更高的钎焊速度。另外,对激光钎焊过程中激光束的扫描路径进行了优化,这种优化能在不增加硬件成本的基础上大大缩短总扫描路程,较大程度地提高激光钎焊速度。最后通过实例对激光钎焊的快速性进行了验证。 相似文献
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