排序方式: 共有35条查询结果,搜索用时 15 毫秒
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利用准单色光干涉理论,计算了2×2平顶高斯超短脉冲激光在远场的干涉图样,分析了激光的时间部分相干性及其存在束间相位差时对相干合成的影响。计算结果表明,当单路激光输出光束线宽小于100 nm时,理想波前的远场光斑图样和峰值光强基本保持不变,当光束线宽大于100 nm时,干涉减弱衍射效应逐渐增强;光束间存在相位差时,时间部分相干性将破坏远场图样随束间相位差的周期性变化,相位差越大干涉越弱;当超过相干长度时,则为非相干合成,但1/6倍相干长度范围内,仍可视为较理想的相干合成,此时焦斑的斯特列尔比大于0.9,对超短脉冲的相干合成影响可忽略。 相似文献
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利用群理论详细分析了磷酸二氢钾(KDP)晶体的拉曼振动模式,得出了其拉曼振动模的归类。并采用拉曼光谱仪测量了Z切退火KDP晶体X(ZZ)珡X,Z(XY)珚Z和Y(XY)X三种散射配置和未退火KDP晶体Z(XY)珚Z配置下的拉曼光谱。根据拉曼选择定则得出X(ZZ)珡X,Z(XY)珚Z和Y(XY)X散射配置下的拉曼峰分别对应A1,B2(LO),B2(TO)对称类振动模,但在Z(XY)珚Z配置下的拉曼光谱中除了B2模,还观察到了A1模,而在Y(XY)X配置下的拉曼光谱中只有B2模,且退火和未退火晶体Z(XY)珚Z配置下的拉曼光谱无明显差别,此结果表明KDP晶体的对称性降低,在背向散射时A1模也具有角度特性,但与晶体的内应力无关,这是由KDP晶体内部结构决定的。 相似文献
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介绍了小波变换的基本概念和特性。应用小波变换对岩石超声波检测信号进行了时频分析和处理。结果表明,该方法是分析处理具有时变谱特性的非平稳信号的一种有效方法。 相似文献
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Laser induced damage experiment is carried out on a large aperture laser facility. Severe damage is observed on a large-aperture fused silica grating which presents dense craters on the front surface and six cracks alternatively located at the front and the rear surface. The bizarre fact about the damage on the grating is that, unlike other optics, the damage craters are almost on the front surface. According to observation, damage phenomenon is due to the stimulated Brillouin scattering (SBS) effect occurring in the grating, which includes the transverse SBS, the back SBS and the zigzag SBS. 相似文献
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A 2ω wedge design is proposed with KDP crystal to disperse the unconverted light away from the target in a high power laser facility for inertial confinement fusion. The ultraviolet B-integral problem is released, and about 1.2 times in color separation angle is achieved according to both theoretical and experimental investigations when compared with conventional 3ω wedge. The frequency conversion etgciency is unaffected when the wedge is along the non-sensitive axis of the tripler. 相似文献
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