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应用一般形式的统一色噪声近似得到了洒料激光色立方模型光强分布的福克-普朗克方程。导出了光强分布函数,描述了光强涨落的实验和数值模拟结果以及色噪声对光强涨落的影响。 相似文献
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强激光大气传输中拉曼散射的数值计算 总被引:1,自引:1,他引:0
用经典理论推导了强激光大气传输中由于氮的转动受激Ranman散射所造成的对传输功率的限制方程,并计算了光强的阈值,得到了阈光强与激光波长和脉宽的关系;此外,还研究了二维效应和激光脉冲系列通过大气时声子激发的累加效应。 相似文献
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为缩短衰减倍率调整的时间,提高激光参数测试的效率,提出激光光强快速衰减算法。衰减倍率精确调整量由当前衰减倍率和采集到的光斑光强真实的最大灰度值共同决定。当因光电接收器件(CCD)饱和造成采集光斑图像失真时,即衰减倍率过小时,由于激光光斑的光强通常满足高斯分布,通过对光斑图像进行处理,去除饱和部分光强信息,对剩余部分光强信息利用最小二乘法进行三维高斯拟合,还原出激光光斑光强的真实分布并获得最大灰度值;当衰减倍率过大时,根据采集光斑图像可以直接获得当前最大灰度值,最后通过计算获得最佳的衰减倍率调整值,实现了激光光强快速准确的调整。算法的有效性通过步进电机带动的双轮可变衰减器及CCD配合得到验证。 相似文献
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高功率激光系统中非线性热像的强度可能达到光学元件的损伤阈值,从而危及系统的安全运行。明确并避免引起最强热像大小的模糊斑,可以降低热像的破坏威胁。通过理论分析与数值模拟方法,研究了高功率激光系统中非线性热像光强与模糊斑大小的关系。根据角谱传输和Bespalov-Talanov小尺度自聚焦理论,推导出一定厚度非线性介质的热像光强表达式,得到了热像光强随模糊斑大小的变化规律,并用数值模拟结果进行了验证。结果表明,随着模糊斑尺寸的增大,热像光强先是单调增大,达到一最大值后单调下降;热像光强最大时对应的模糊斑大小基本上与由Bespalov-Talanov小尺度自聚焦理论决定的最快增长小尺度调制尺寸相同。 相似文献
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泵浦光强对激光相位共轭波非线性效应的影响 总被引:2,自引:0,他引:2
分析了泵浦光强对激光相位共轭谐振腔中探测光场的作用。基于稳定性定理,通过确定系统的Lyapunov指数,数值计算了在不同泵浦光强下的激光相位共轭波的非线性效应。结果显示,泵浦光强是系统的控制参量。调节泵浦光强的数值,系统的动力学性质发生了改变,可以呈现一周期、二周期、四周期以及倍周期分岔、周期并缩和混沌现象。 相似文献
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为了研究飞秒激光诱导水光学击穿阈值随激光脉冲参数的变化关系,采用四阶RungeKutta方法对飞秒激光诱导水光学击穿的椭球体模型进行了不同脉宽(40~540fs)、波长(400~1200nm)和光斑尺寸(0~200μm)下的数值模拟。通过控制变量法得出阈值光强与这些激光脉冲参数的关系曲线图,据此定性分析了阈值光强与激光脉冲参数的变化特征趋势。应用光强与功率、能量、辐照曝光量和电场强度之间的关系,得到了它们随激光脉冲参数脉宽、波长和光斑尺寸的动态关系,这为进一步研究飞秒激光与水和含水介质的相互作用提供了理论依据。 相似文献
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C. G. Bollini P. Marchiano M. C. Rocca 《International Journal of Theoretical Physics》2007,46(12):3030-3059
In this work, a general definition of convolution between two arbitrary Ultradistributions of Exponential type (UET) is given.
The product of two arbitrary UET is defined via the convolution of its corresponding Fourier Transforms. Some examples of
convolution of two UET are given.
Expressions for the Fourier Transform of spherically symmetric (in Euclidean space) and Lorentz invariant (in Minkowskian
space) UET in term of modified Bessel distributions are obtained (Generalization of Bochner’s theorem).
The generalization to UET of dimensional regularization in configuration space is obtained in both, Euclidean and Minkowskian
spaces
As an application of our formalism, we give a solution to the question of normalization of resonances in Quantum Mechanics.
General formulae for convolution of even, spherically symmetric and Lorentz invariant UET are obtained and several examples
of application are given.
This work was partially supported by Consejo Nacional de Investigaciones Científicas and Comisión de Investigaciones Científicas
de la Pcia. de Buenos Aires; Argentina. 相似文献
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从矢量瑞利-索末菲衍射积分公式出发,以非傍轴矢量余弦-高斯(CoG)光束为例,对非傍轴矢量光束的两种光强表示式,即传统光强公式和时间平均坡印廷矢量的z分量进行了比较研究.对非傍轴矢量CoG光束轴上和横向光强分布详细的数值计算和比较结果表明,两种光强表示式之间的相对误差η与w0/λ、z/λ和偏心参量b有关,其中w0,λ和z分别为束腰宽度,波长和传输距离.当偏心参量b较小,且束腰宽度与波长相比不很小时,例如,b≤0.8,w0/λ≥0.8,z/λ=10时,二者间的最大相对误差ηmax<2%,传统光强公式可以使用. 相似文献
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ZHANG Peng ZHAO Jianlin XU Honglai SUN Yidong YANG Dexing & WANG Meirong . Institute of Optical Information Science Technology School of Science Northwestern Polytechnical University Xi’an China . School of Science Xi’an Jiaotong University Xi’an China 《中国科学G辑(英文版)》2005,48(4):399-412
1 IntroductionSince the discovery of photorefractive effect by Ashkin et al. at the Bell laboratories in 1966[1], such effects of light-induced refractive index changes in electro-optic oxide crystals have attracted great attention because of their potential use in volume holo- graphic storage[2], optical information processing[3], optical spatial solitons[4], and light-induced optical waveguides[5―9]. The photo-induced index changes are the basis ofthe entire photorefractive phenomena in pho… 相似文献
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Ultrasonic extraction technique (UET) was used to extract crude polysaccharides (OCAP) from Ornithogalum Caudatum Ait (OCA), an orthogonal experiment (L(9) (3)(4)) was applied to optimize extraction conditions. Membrane separation technology and gel filtration chromatography were used to fractionate OCAP, the antioxidant and immunomodulatory activities were evaluated by radical scavenging and spleen lymphocyte proliferation assay. The optimal conditions were determined: extraction time 60min, ultrasound power 500W, ratio of water to raw material 30ml/g and extraction number 3. Under these conditions, the yield of OCAP was 36.77±1.76%. OCAP was fractionated into three major fractions (OCAP-I, OCAP-II and OCAP-II), that all fractions possessed considerable antioxidant activity. OCAP-II and OCAP-III exhibited good immunomodulatory activities. The results indicated that UET is a very useful method for extraction bioactive polysaccharides from plant materials. OCAP could be explored as a potential antioxidant and immunostimulating agent for use in medicine or functional foods. 相似文献
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Theoretical expressions for the overall values of three Booth type R-indices based on intensity variables are derived. The
results are applicable to crystals of any space group containing any number and type of atoms at general positions in the
asymmetric unit. The theoretical results were tested in the case of models of a few crystal structures. 相似文献