柱面球差透镜聚焦部分相干光束的焦移

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.     

数值法研究光的圆孔衍射实验现象

在平行平面波近似的情况下,数值法求解菲涅耳-基尔霍夫衍射积分公式,得到平行平面光波通过圆孔衍射后的光强分布图.通过对纵向及横向光强分布图的数值分析,验证了轴上点光强由菲涅耳数决定,菲涅耳数大于1时为菲涅耳衍射区,菲涅耳数小于1时为夫琅禾费衍射区.在近场,光强分布为明暗相间的环形条纹;在远场,光束演化成束腰位置在圆孔处的高斯光束,仿真结果与理论和实验结果基本一致.本仿真结果将光衍射的抽象理论直观化、可视化.     

部分相干电磁光束的焦移

 基于有效菲涅耳数的概念,给出一种简单的表达式来评估部分相干电磁光束经圆形光阑透镜后所产生的相对焦移,对部分相干电磁光束经透镜聚焦的情况进行了研究。结果表明:当交叉谱密度函数的非对角元素为零时,有效菲涅耳数不仅依赖于真实的菲涅耳数大小,而且依赖于光束的偏振分布和入射部分相干电磁光束两个偏振分量的空间相干长度;相对焦移量仅由等效菲涅耳数决定。将此方法与数值积分法进行的比较表明,等效菲涅耳数可以简单、准确地评估焦移。     

关于菲涅耳衍射图样相似性的分析与讨论

与夫琅禾费衍射不同,菲涅耳衍射图样对于给定波长,当衍射距离变化或输入图像几何缩放时一般都不具有相似性.但我们的分析表明,若波长、衍射距离和输入图像几何线度诸参数满足一定关系,或对于某些特殊类型孔径,菲涅耳衍射图样有可能彼此相似.本文导出了在上述诸参数发生变化时菲涅耳衍射图样保持相似性的普适条件,以及此时衍射图样大小与诸参数的定量关系,并对包括圆孔衍射和直边衍射等情况都得到了一系列有价值的推论.     

高斯光束照射下的圆盘夫琅禾费衍射

推导了高斯光束照射圆孔或圆盘的衍射场普遍表达式，计算了半波带数接近于零的情况下上述衍射场的数据，进而分析了圆盘衍射场在艾里斑中增加一个暗环的原因。     

Focal Shift of Paraxial Gaussian Beams in a Left-Handed Material Slab Lens

Focal shift is inevitable in conventional lens systems due to the Fresnel number and angular aperture. In this Letter, we demonstrate that there is no focal shift when a paraxial Gaussian beam passes through a left-handed material slab lens without absorption or gain. However, the effect is exhibited in the presence of absorption or gain, and becomes larger as the absorption or gain increases. When the absorption is equal to the gain, the phenomenon of the focal shift caused by the gain is more obvious. In addition, the field distribution is not affected by the absorption or gain and always remains Gaussian both in internal and external focus planes.     

部分相干光经柱面球差透镜聚焦所产生的焦移

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.     

经典菲涅耳变换的量子力学对应

介绍经典菲涅耳变换的量子力学对应,它是相干态在相空间中的代表点做辛运动所对应的量子菲涅耳算符.     

高斯光束下的圆屏衍射

计算分析了用高斯光束作光源时，圆屏衍射轴线上的光强分布规律，并与球面波入射的情况进行了对比．     

菲涅耳全息图的显微成像

从理论上描述了菲涅耳全息图显微成像的原理,并进行了菲涅耳全息图显微成像的初步试验。     

EchSGB远距离照明条件下的焦开关

推导了复变量双曲余弦平方-高斯光束(EchSGB)被无光阑透镜聚焦后的轴上光强分布公式,在此基础上通过数值计算和分析发现,EchSGB只有在远距离照明条件下才存在焦开关现象.焦点跃变位置随光束参数和对应高斯光束的菲涅尔数不同而变化,得到了EchSGB在平顶情形下产生焦开关的相对入射距离为11.13,表明在远距离照明和无光阑透镜精密调焦时,对于EchSGB要考虑焦开关现象的影响.     

热晕效应相位补偿定标参量的数值分析

利用数值模拟的方法，对三种不同发射口径情况下准直强激光水平传输稳态热晕效应的自适应光学相位补偿进行了计算。结果表明，定标参量ND／NFB可充分描述其相位补偿的效果，且对理想柔形镜及实际自适应光学系统相位补偿而言，其不稳定性定标参量的阈值分别为6.0、0.35。当ND／NFB于阈值时，相位补偿效果理想且随ND／NFB的改变Strehl比变化平缓；而当ND/NFB大于阈值时，由于相位补偿不稳定性的增强，补偿效果迅速变差。     

Transformation of laser radiation by Gaussian apertures

The transformation of simple Gaussian light beams by lenses with a complex focal length is investigated in an approximation of paraxial optics. The results obtained are compared with the corresponding results of geometric optics into which they go over in limiting cases. A. N. Sevchenko Scientific-Research Institute of Physical Problems, 7, Kurchatov St., Minsk, 220064, Belarus. Translated, from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 471–478, July–August, 1997.     

厄米-高斯光束的焦开关

考虑了由光阑和透镜组成的简单光学系统。研究表明，当厄米-高斯光束入射这一系统，在系统和光束参数满足一定条件时会出现称为焦开关的新现象。详细的数值计算和物理分析说明了厄米-高斯光束的焦开关特性。与已有的工作做了比较，并指出了焦开关可能的应用。     

Effective Fresnel number and focal shifts for focused cylindrical spherical aberrated beams

We define the effective Fresnel number of a focused cylindrical spherical aberrated beam. Based on the effective Fresnel number, a simple analytical expression for evaluating the relative focal shift is presented. It is shown that the relative focal shift is determined by the effective Fresnel number, which is dependent on the spherical aberration and Fresnel number of the focused system. To illustrate the approach, a comparison between the results obtained by this new method and the numerical integral calculation is made. The results indicate that the relative focal shift can be simply and exactly evaluated using this new method. A special case is discussed, in which the effective Fresnel number turns out to be a pure imaginary number, and the corresponding relative focal shift is positive.     

Changes in the spectrum of twist anisotropic Gaussian Schell-model beams propagating through turbulent atmosphere

Based on the extended Huygens-Fresnel principle, the spectrum of twist anisotropic Gaussian Schell-model (TAGSM) beams propagating through turbulent atmosphere is derived analytically by using the partially coherent complex curvature tensor. The relative spectral shift of TAGSM beams propagating through turbulent atmosphere is closely related with the strength of atmospheric turbulence, the beam’s parameter and the radial coordinate. The on-axis spectral shift of TAGSM beams propagating through turbulent atmosphere changes from blue shift to red shift with the increasing of the propagation distance z, and at a certain propagation distance z, there exists a rapid transition of the spectrum at the critical position r_c.     

Axial intensity distribution and focal shifts of focused partially coherent conical Bessel–Gauss beams

Based on the generalized Huygens–Fresnel diffraction integral and the theory of partially coherent light, the axial intensity distribution and the focal shifts of focused partially coherent conical Bessel–Gauss beams are investigated. The dependence of the maximum on-axis intensity and the associated focal shift on the Fresnel number and the coherence parameter are examined and illustrated numerically. The results related to the J ₀-correlated beams and the fully coherent Bessel–Gauss beams are obtained as particular cases of this study.     

Propagation of relative phase shift of apertured Gaussian beams through axisymmetric optical systems

When a Gaussian beam is apertured, it undergoes a phase shift as well as a focal shift. The relative phase shift of an apertured Gaussian beam through an axisymmetric optical system written in ABCD matrix is analyzed by applying Collins' diffraction integral formula. And, more important, the condition of dispeling the relative phase shift is obtained, which is related with the Fresnel number. At last, some extensions are given.     

左手材料平板对傍轴高斯光束聚焦特性分析

在傍轴近似下,推导出了左手材料平板聚焦系统的传输矩阵,并利用ABCD定律得到了高斯光束在左手材料中和经过平板透镜聚焦后的传输公式。高斯光束在左手材料内部和像空间的传输公式的研究表明:像高斯光束和物高斯光束束腰大小一致,即左手材料平板透镜实际上对高斯光束没有聚焦作用。研究同时表明左手材料平板对高斯光束的聚焦与几何光学成像规律完全一致,而不存在一般透镜聚焦时的焦移效应。     

高斯光束通过双焦透镜的聚焦特性

 从Collins公式出发,研究了高斯光束通过双焦透镜后的聚焦特性。在无光阑的情况下,给出了轴上光强和x, y方向两束腰及其位置的解析公式。详细的数值计算表明,轴上光强最大点位于其中一个束腰位置附近或者相重合,但始终不能超过透镜较大的焦点。并且,相对束腰的位移随光阑效应的增加而增加。