共查询到17条相似文献,搜索用时 564 毫秒
1.
2.
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
3.
4.
5.
《中国光学与应用光学文摘》2004,(5)
O435 2004053247 “飞行光学”焦移研究=Research on the focal shift in flying opttcs[刊,中]/赵全忠(中科院上海光机所,上海(201800))。程兆谷…∥中国激光。—2004,31(1)。—62-64 基于焦移传输理论,推导了“飞行光学”中焦移、相对焦移的表达式,分析了“飞行距离”、瑞利长度和聚焦镜焦 相似文献
6.
基于厄米-双曲余弦高斯光束通过无光阑限制薄透镜聚焦的解析传输公式,研究了厄米-双曲余弦高斯光束聚焦区域的光强分布,并对光束的焦移进行了分析,讨论了偏心参数对光强主极大位置的影响。结果表明:TEM11模厄米-双曲余弦高斯光束的相对焦移(绝对值)随偏心参数和菲涅尔数的减小而增大,菲涅尔数较大时相对焦移趋于零。TEM22模光束在偏心参数小于0.54时,轴外与轴上光强极大值的比值大于1,此时光强主极大在轴外,偏心参数大于0.54时则相反;在偏心参数等于0.54时比值为1,此时光束有两个主极大,偏心参数愈大光强愈集中于轴上。使用LW法和GH法得到的TEM22模光束的相对焦移(绝对值)随偏心参数和菲涅尔数的变化规律与TEM11模光束一致,但相同参数下使用这两种方法得出的具体结果不同。 相似文献
7.
从理论上研究部分相干光被一环形透镜聚焦,在焦点附近的轴上点的光强分布。研究结果表明,当部分相干光被一环形透镜聚焦时,最大聚焦光强不在几何焦点,而是位于透镜与几何焦点之间,出现焦移现象。并且,焦移量不仅依赖于透镜外半径的菲涅耳数,还依赖于部分相干光的空间相干度和中心拦截比。透镜的菲涅耳数越小,焦移越大;部分相干光的空间相干度越低,焦移越大。当菲涅耳数一定时,环形透镜的中心拦截比越大,焦移越大;当空间相干度很小时,情况就变得比较复杂。 相似文献
8.
9.
10.
11.
Zhangrong Mei 《Optics Communications》2011,284(22):5248-5252
The focal shifts of focused truncated random electromagnetic beams are investigated. Based on the complex Gaussian expansion method for a hard-edged aperture function, the analytical propagation formula of cross-spectral density matrix for a random electromagnetic beam focused by an optical system with a thin lens and a circular aperture is derived. The Fresnel numbers related with the beam and system parameters are defined and used to examine focal shifts. The dependence of the focal shifts on the different Fresnel numbers and polarization distribution are discussed in detail with numerical examples. 相似文献
12.
Focusing properties of flattened Gaussian beams (FGBs) passing through an annular lens is studied based on the Collins formula. It is found that the on-axis irradiance distributions of focused FGBs are unsymmetrical with respect to the geometrical focal plane even for large values of Fresnel number Fw associated with the beam, so that there exist focal shifts in general. Detailed numerical results show the dependence of focal shifts on the beam and system parameters. Focal shifts of FGBs by a lens without central obscuration and focal shifts of Gaussian beams by an annular lens can be treated as special cases of the obscure ratio =0 and beam order N=0, respectively. Furthermore, focal shifts of plane waves by an annular lens can also be treated as a special case of N=0 and Fw→∞. 相似文献
13.
Based on vectorial Debye theory, the tightly focusing properties of linearly polarized vortex beams through a dielectric interface are studied. Then the intensity distribution in the focal region is investigated in detail by numerical calculations. The focal shifts induced by the mismatch of the refractive indices across the interface has been found. And the dependence of focal shifts and spot size of the focused field on the probe depth and numerical aperture of the objective are presented. Furthermore, the characteristic of intensity pattern of the cross section of the focused field is illustrated, finding that the intensity pattern rotates with the propagation of beams. 相似文献
14.
激光波带片衍射性质的数值模拟 总被引:1,自引:1,他引:0
根据亥姆霍兹-基尔霍夫积分,对菲涅尔波带片的高斯激光场在轴向、径向强度分布进行了理论分析,研究了高斯激光束照射下波带片的衍射场规律.数值计算表明:沿轴向光场呈系列焦点,各焦点附近光强分布有振荡现象,随焦点级次的增大光强迅速增大;有焦移现象,焦移量随焦点级次的增大而增大;焦深随焦点级次的升高按平方反比律减小,随波带数减小或焦距增大而增大.在焦平面上,光斑大小与最外环宽度成正比,与焦点级次成反比. 相似文献
15.
16.
Axisymmetric Bessel-modulated Gaussian beam with quadratic radial dependence (QBG beam) has attracted much attention recently. In this paper, the focal shift of the cylindrical vector QBG beam with radial variance phase wavefront is investigated theoretically by vector diffraction theory. Results show that focus shifts considerably by changing the phase parameter C that indicates the radial phase variance speed. Under condition of small beam parameter μ of cylindrical vector QBG beam, there is one focal peak that shifts far away from optical aperture on increasing C. When μ increases, there may occur two focal peaks that also shift remarkably on increasing C. And it was found that the dependence of focal shift distance on increasing phase parameter is linear. Phase parameter adjusts the focal shift distance, while, polarization angle does not affect focal shift obviously. 相似文献
17.
A study of the spectral shifts of a well-known type of partially coherent field, namely, one formed by Gaussian Schell model beams, propagating beyond an optical system reveals that there are no shifts in the geometric-image plane, whereas the greatest (blue) shift occurs in the back focal plane. These results are relevant for spectroradiometric measurements. 相似文献