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高斯光束经过负球差透镜的聚焦 总被引:2,自引:0,他引:2
本文讨论高斯光束经过负球差透镜的聚焦,得到了聚焦光场轴上点的光强分布的表示式,并对其进行数值计算。数值计算结果表明,在负球差的情况下,得到光强的最大点位置(最佳聚焦点)相对于无球差情况,往透镜方向移动,并且,最佳聚焦点的光强较无球差时大,当Nw=1,Na=5,kS1=-0.2时,得到的最佳聚焦点的光强是无球差时的1.34倍。本文还讨论了透镜的菲涅尔数对聚焦光场分布的影响。结果表明,当透镜的菲涅尔数小于1时,球差对高斯光束的聚焦的影响可以忽略。 相似文献
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基于部分相干光的传输理论,研究了部分相干平顶高斯光束通过球差透镜聚焦后轴上点的光强分布。数值计算表明:轴上最佳聚焦点随着球差从负到正的变化而向几何焦点方向移动;光束阶数越大,实现最佳聚焦点越过几何焦点所需的正球差值越小;正负球差对应的最佳聚焦点始终分居于无球差时最佳聚焦点的两侧;轴上最佳聚焦点的光强随着球差从负到正的变化而变小;当正负球差绝对值较大时,光强随球差的变化较为缓慢,而在球差值为0附近,光强随球差的变化比较剧烈。 相似文献
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基于Tovar提出的平顶多高斯光束模型,给出了环状光束模型。利用广义惠更斯-菲涅耳衍射积分理论,对环状光束通过像散透镜后的传输和聚焦特性进行计算和分析,并讨论了透镜像散对环状光束经透镜变换后对光束质量的影响。研究结果表明:环状光束通过像散透镜后变为非旋转对称光束;聚焦光强随着透镜像散系数的增大而逐渐减弱,聚焦光斑的方位仅由像散系数确定;在光束阶数和入射光波波长一定的情况下,环状光束通过像散透镜的变换特性和光束质量不仅与透镜像散系数有关,还与系统菲涅耳数有关,像散系数增大或菲涅耳数减小时,光束质量变差。 相似文献
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采用Strehl比、桶中功率、β参数和束宽描述远场光束质量,研究了光束控制系统热效应和球差对远场激光光束质量的影响.用四维仿真程序作了详细计算,给出了数值计算结果并进行了物理分析.研究表明,传输通道的热效应和正球差会使远场光强分布扩展,可聚焦能力下降,光束质量变差.有意义的是,当激光发射功率达到一定值时,合适选取负球差会在几何焦面得到比无球差时更高的峰值光强和更好的可聚焦能力.但在以前的工作中,由于焦移,类似的结论是在实际焦面上得出的.非线性热晕的存在是其物理原因,对此用数值计算例子作了说明.
关键词:
高功率激光
热效应
光束控制系统
球差 相似文献
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部分相干修正贝塞尔高斯光束通过球差透镜的聚焦特性 总被引:2,自引:2,他引:0
由部分相干光的传输理论出发,对部分相干修正贝塞尔高斯光束通过球差透镜聚焦后轴上光强分布进行了研究.数值计算表明:当光谱相干度较小时,正、负球差对应的最佳聚焦点位于无球差时对应的最佳聚焦点的两侧;当光谱相干度较大时,正、负球差对应的最佳聚焦点将位于无球差时对应的最佳聚焦点的左侧.研究进一步表明,最佳聚焦点随着透镜菲涅耳数的增大向几何焦点方向靠近,并趋于一个定值.当光束菲涅耳数为1时,无球差时对应的最佳聚焦点逐渐趋于0.908,该值与光谱相干度无关,当透镜具有球差时,该值与光谱相干度有关. 相似文献
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柱面球差透镜聚焦部分相干光束的焦移 总被引:1,自引:1,他引:0
通过定义聚焦光束的等效菲涅耳数,研究了部分相干光经柱面球差透镜聚焦后的轴上光强分布,得到了相对焦移的简单公式,即相对焦移反比于等效菲涅耳数的平方.结果表明,这种基于等效菲涅耳数的计算聚焦光学系统的焦移方法是计算部分相干光束经球差透镜聚焦相对焦移简单且有效方法.还讨论了一种特殊等效菲涅耳数为纯虚数情况.结果证明,在这种情况下,该相对焦移简单公式仍然有效. 相似文献
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《中国光学与应用光学文摘》2007,(3)
激光物理TN2412007032142部分相干平顶光束的实验研究=Experi mental investiga-tions on partially coherent flattop beamprofiles[刊,中]/董梅梅(华侨大学光学与光子学研究所.福建,泉州(362021)),蒲继雄//光电工程.?2007,34(1).?104-107利用对入射光进行相干度调制的方法,在实验上研究了聚焦光场中的部分相干平顶光束,用CCD记录了光束的产生和演变过程,验证了聚焦光场中部分相干平顶光束的存在。此外,还研究了对于不同的聚焦透镜焦距和环形光阑中心拦截比,不同空间相干度对平顶光束的影响。研究表明,两处平顶光束的大小及两处平顶光束… 相似文献
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The effect of spherical aberration on scintillations of Gaussian beams in weak, moderate and strong turbulence is studied using numerical simulation method. It is found that the effect of the negative spherical aberration on the on-axis scintillation index is quite different from that of the positive spherical aberration. In weak turbulence, the positive spherical aberration results in a decrease of the on-axis scintillation index on propagation, but the negative spherical aberration results in an increase of the on-axis scintillation index when the propagation distance is not large. In particular, in weak turbulence the negative spherical aberration may cause peaks of the on-axis scintillation index, and the peaks disappear in moderate and strong turbulence, which is explained in physics. The strong turbulence leads to less discrepancy among scintillations of Gaussian beams with and without spherical aberration. 相似文献
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We developed an expression that describes the hollow Gaussian beams (HGBs) passing through a spherically aberrated lens by using the Collins formula. The radial intensity distribution in both spherical aberration SA free lens, lens that exhibits relatively large in both positive spherical aberration PSA, and negative spherical aberration NSA is calculated. Numerical calculations are made and the results show that the PSA and NSA have a strong influence on the intensity distribution especially at the focus. The study showed remarkable results for which there is no hollow Gaussian beam at a large NSA along the optical axis at the focus. In addition, we found that the DSS, and wr of focused hollow Gaussian beams in the focal region depend not only on the beam radius, and beam order; but also on the spherical aberration. 相似文献
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Wang Chun-Fang Tao Xiang-Yang Nie Yi-You Zeng zhao-Yang 《Optics & Laser Technology》2007,39(2):430-434
Based on the Collins formula, we study the focal switch of spherically aberrated Laguerre–Gaussian (L–G) beams passing through an optical system with the aperture and lens separated. Our results demonstrate that the behavior of the focal switch of spherically aberrated L–G beams is generally dependent on the spherical aberration coefficient, truncation parameter, Fresnel number and mode indices. The spherical aberration affects the relative focal shift, critical position of the focal switch and the relative transition. We also illustrate that there exists a minimum in addition to a maximum in the truncation parameter. Only inside the region between the minimum and the maximum the focal switch effect can be expected. The region depends on the spherical aberration coefficient as well as the Fresnel number. 相似文献
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The phase singularities of focused dark-hollow Gaussian beams in the presence of spherical aberration are studied. It is shown that the evolution behavior of phase singularities of focused dark-hollow Gaussian beams in the focal region depends not only on the truncation parameter and beam order, but also on the spherical aberration. The spherical aberration leads to an asymmetric spatial distribution of singularities outside the focal plane and to a shift of singularities near the focal plane. The reorganization process of singularities and spatial distribution of singularities are additionally dependent on the sign of the spherical aberration. The results are illustrated by numerical examples. 相似文献
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The conversion efficiency of THG on the flattened Gaussian and Gaussian beams is obtained in detail numerical stimulation for CsLiB6O10.The conversion efficiencies of 86.7% and 96% of the flattened Gaussian are larger than those of Gaussian beams of 72.6% and 88% under type I and type 11(1) phase matching. The efficiencies affected by the pump intensity, polarization rate, crystal lengths and orders of the flattened Gaussian beams were presented. 相似文献
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本文从泽尼克一高斯国多项式出发,讨论了三种初级象差(球差、营差、象散)在平衡及未平衡状态下的标准偏差同衍射孔半径与高斯光束半径之比α的关系.最后讨论了在均匀光波的最佳校正状态下,高斯光束初级象差同α的关系,得到高斯光束的初级象差可按照均匀光波象差理论进行校正的结论. 相似文献
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利用广义惠更斯-菲涅耳衍射积分法,推导出平顶高斯光束在梯度折射率介质中传输时的解析表达式,对平顶高斯光束在梯度折射率介质中的传输特性进行了分析,讨论了介质梯度折射率系数和光束阶数对传输特性的影响。研究表明,平顶高斯光束在梯度折射率介质中传输时轴上光强分布呈现周期性变化,其周期决定于介质梯度折射率系数,而与光束的阶数无关;轴上峰值处的横向光强分布受梯度折射率系数和光束阶数的影响较大,横向光强的最大值随着梯度折射率系数的增大而增大。 相似文献