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部分相干光在大气湍流中的光强闪烁效应 总被引:5,自引:0,他引:5
以修正Rytov方法为基础,利用部分相干高斯-谢尔(GSM)光束模型并结合Andrews的唯像闪烁模型,研究部分相干光在大气湍流中的光强闪烁效应。推导出适用于不同湍流情形的部分相干光对数光强起伏方差表达式,系统分析了部分相干光在大气湍流中的光强起伏方差。结果表明:在同等的湍流环境下,部分相干光比完全相干光的光强起伏方差要小;光束相干性越差,光强起伏越小,抗湍流能力越强。在不同大气湍流情形下,光源相干性、大气折射率常数等参数对光强起伏都有不同程度的影响。 相似文献
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《中国光学与应用光学文摘》2004,(1)
O436.1 2004010041 多束相干光叠加的计算机模拟=Computer simulation forsuperimposition of multiple coherent laser beams[刊,中]/张春梅(电子科技大学光电信息学院.四川,成都(610054)),吴健…∥光电工程.—2003,30(2).—18-20 研究了具有空间不对称分布的多束相干光的叠加问题。对参考平面上相干光产生的干涉光强分布进行理论推导和数值计算,从理论上定量地分析了多束相干光的波矢量、偏振态对干涉光强分布的影响。模拟结果表明 相似文献
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光场相干性对线聚焦均匀性的影响 总被引:1,自引:0,他引:1
采用高斯-谢尔模型(GSM)光束来模拟部分相干光,研究了具有不同相干多数β的GSM光束经柱透镜列阵系统变换后聚焦场的光强分布,并详细讨论了衍射效应和干涉效应对辐照均匀性的影响。 相似文献
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相干光经湍流传输引起光强闪烁效应,理论研究表明利用部分相干光可降低该影响,而相关的实验验证鲜有报道。利用水介质的对流湍流池模拟产生了Rytov方差为0.04~0.16的湍流,进行了弱起伏区湍流中部分相干光及相干光的传输实验,由接收光强计算出其光强闪烁指数随湍流Rytov方差的变化关系。实验结果表明:随着湍流强度的增加,部分相干光与相干光的闪烁效应均增强,但部分相干光的闪烁指数小于相干光。将实验数据与Andrews等人建立的闪烁指数理论模型进行比较,得出了较为一致的结论。 相似文献
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相干光经湍流传输引起光强闪烁效应,理论研究表明利用部分相干光可降低该影响,而相关的实验验证鲜有报道。利用水介质的对流湍流池模拟产生了Rytov方差为0.04~0.16的湍流,进行了弱起伏区湍流中部分相干光及相干光的传输实验,由接收光强计算出其光强闪烁指数随湍流Rytov方差的变化关系。实验结果表明:随着湍流强度的增加,部分相干光与相干光的闪烁效应均增强,但部分相干光的闪烁指数小于相干光。将实验数据与Andrews等人建立的闪烁指数理论模型进行比较,得出了较为一致的结论。 相似文献
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部分相干光经柱面球差透镜聚焦所产生的焦移 总被引:7,自引:7,他引:0
利用Collins公式得出光强均匀部分相干光经柱面球差透镜聚焦后的轴上光强分布,并通过数值模拟的方法研究了入射光的菲涅耳数、相干度和透镜的球差对轴上点光强分布的影响.结果显示,当菲涅耳数较小、空间相干度较小的部分相干光经无球差透镜聚焦时,轴上点光强分布会产生焦移现象,而当部分相干光被球差透镜聚焦时,也会有焦移现象产生. 相似文献
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研究了菲涅耳衍射区和夫琅和费衍射区动态部分相干光散斑的特性.利用部分相干光互强度传播的理论,得出了在部分相干光照明时,由运动散射体产生的动态散斑光强时空交叉的自相关函数的一般形式,并由此得出了散斑沸腾和平移的一般规律.通过适当选择光源和调整光路参数,在实验上得到了菲涅耳和夫琅和费衍射区的部分相干光散斑,对夫琅和费面上的动态部分相干光散斑的平移和沸腾现象进行了定性研究;采用光子计数及数据自动采集的方法,对部分相干光散斑随时间的演化及动态部分相干光散斑的沸腾进行了定量测量.这些实验结果与理论结果相符合.
关键词:
部分相干光动态散斑
时空交叉相关函数
沸腾 相似文献
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The spatial correlation properties and the spectral intensity distributions of focused Gaussian Schell-model (GSM) array beams are studied in detail. The closed-form expressions for the spectral degree of coherence and the spectral intensity of focused GSM array beams are derived. It is shown that the spectral degree of coherence of focused GSM array beams is the same as that of focused GSM beams in the focal plane. On the other hand, it is found that, in the focal plane the spectral intensity distribution of focused GSM array beams is the fringe pattern when the value of the coherence length is small. However, it becomes one peak located at the center as the value of the coherence length is large enough. In the focal plane, the spectral intensity maximum increases and the width of the normalized spectral intensity distribution decreases as the beam number increases. In general, for GSM array beams, the width of the modulus of the spectral degree of coherence in the focal plane always exceeds that of the normalized spectral intensity distribution, which is different from the behavior of focused GSM beams. In addition, the power in the bucket (PIB) and the beam propagation factor (M2 factor) are also discussed. The main results are explained physically. 相似文献
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Propagation of partially coherent beams carrying an edge dislocation through atmospheric turbulence along a slant path 下载免费PDF全文
This paper derives the explicit expressions for the average intensity, beam width and angular spread of Gaussian Schell-model (GSM) beams with edge dislocation propagating through atmospheric turbulence along a slant path. The propagation of GSM beams with edge dislocation through horizontal atmospheric turbulence can be treated as a special case through a slant one. The propagation properties of GSM beams with edge dislocation through slant atmospheric turbulence are studied, where the influence of edge dislocation parameters including the slope p and off-axis distance d on the spreading of GSM beams with edge dislocation in atmospheric turbulence is stressed. It shows that the spreading of the intensity profile of GSM beams with edge dislocation along a slant path is smaller than that along a horizontal path in the long-distance atmospheric propagation. The larger the slope vert pvert and the smaller the off-axis distance vert dvert are, the less the beam-width spreading and angular spread of GSM beams with edge dislocation are affected by turbulence. The GSM beams with edge dislocation is less affected by turbulence than that of GSM beams without edge dislocation. The results are illustrated numerically and their validity is interpreted physically. 相似文献
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利用惠更斯-菲涅耳衍射积分公式,推导了高斯-谢尔模型光束经非线性克尔介质的表面缺陷调制后的交叉谱密度公式,研究了受调制高斯-谢尔光束的光强演化特性。数值模拟表明:缺陷也可导致部分相干光束在介质后表面产生一个极强点,缺陷越大,极强点越远离介质。非线性折射率为正值或负值的介质也分别使部分相干光束发生会聚或发散现象。空间相干长度越长以及附加相移和缺陷尺寸越大,光场受调制越厉害。 相似文献
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基于广义惠更斯-菲涅耳原理,以高斯-谢尔模型(GSM)涡旋光束作为典型的部分相干涡旋光束,推导出GSM涡旋光束通过大气湍流斜程传输的平均光强、均方根束宽和交叉谱密度函数的解析表达式,并用以研究了大气湍流中上行和下行对GSM涡旋光束传输和对相干涡旋的影响.结果表明,在相同条件下,GSM涡旋光束下行传输受大气湍流的影响要小于上行传输,下行传输时相干涡旋拓扑电荷守恒距离要长于上行传输.对所得结果做了物理解释.
关键词:
部分相干涡旋光束
相干涡旋
大气湍流
上行和下行传输 相似文献
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The analytical expression for the beam propagation factor (M2-factor) of Gaussian Schell-model (GSM) array beams propagating through atmospheric turbulence is derived. It is shown that the M2-factor of GSM array beams depends on the beam number, the relative beam separation distance, the beam coherence parameter, the type of beam superposition, and the strength of turbulence. The turbulence results in an increase of the M2-factor. However, for the superposition of the intensity the M2-factor is less sensitive to turbulence than that for the superposition of the cross-spectral density function. The M2-factor of GSM array beams is larger than that of the corresponding Gaussian array beams. However, the M2-factor of GSM array beams is less affected by turbulence than that of the corresponding Gaussian array beams. For the superposition of the cross-spectral density function a minimum of the M2-factor of GSM array beams may appear in turbulence, which is even smaller than that of the corresponding single GSM beams. 相似文献
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Wanrong Gao 《Optics Communications》2010,283(23):4572-4581
The effects of position-dependent correlations between the x- and y-components of the partially coherent incident electromagnetic beam on the spectral intensity distribution in the focal plane and along the z-axis of an optical imaging system with a high-numerical aperture are studied. The electromagnetic Gaussian Schell-model (GSM) beam is employed as an example to illustrate the analysis. 相似文献
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Using the extended Huygens-Fresnel principle and the quadratic approximation of the phase structure function, and taking the Gaussian Schell-model (GSM) vortex beam as a typical example of partially coherent vortex beams, the explicit expressions for the cross-spectral density function and average intensity of GSM vortex beams with topological charge m=+1 propagating through slant atmospheric turbulence are derived, and used to study the propagation properties of GSM vortex beams in atmospheric turbulence along a slant path and evolution behavior of coherence vortices. It is shown that the spreading of GSM vortex beams along a horizontal path is larger than that along a slant path in the long atmospheric propagation. The propagation through horizontal atmospheric turbulence can be treated as a special case of the altitude-independent structure constant. The position of coherence vortices in slant atmospheric turbulence does not coincide with that in horizontal atmospheric turbulence, and the dependence of position of coherence vortices on the zenith angle, wavelength and reference point is illustrated by numerical examples. A comparison with the previous work is also made. 相似文献