共查询到20条相似文献,搜索用时 967 毫秒
1.
提出了一种基于轴棱锥产生零阶近似无衍射Mathieu光束的新方法,利用轴棱锥聚焦具有椭圆高斯振幅调制的平面波,得到近似零阶无衍射Mathieu光束.根据椭圆高斯平面波经轴棱锥衍射的衍射积分公式,对光强分布进行了数值模拟,依据几何光学模型计算了近似无衍射Mathieu光束的最大无衍射距离,并设计了实验对理论模拟的结果进行了验证.实验采用柱透镜和准直扩束系统变换圆高斯光束产生具有椭圆高斯振幅调制的平面波,用轴棱锥聚焦该平面波后得到近似无衍射Mathieu光束,实验结果与理论模拟和计算相符. 相似文献
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Starting from the vectorial Rayleigh diffraction integral formula and without using the far-field approximation, a solution of the wave equation beyond the paraxial approximation is found, which represents vectorial non-paraxial elliptical Gaussian beams in free space. The far-field expressions for non-paraxial Gaussian beams and elliptical Gaussian beams can be regarded as special cases treated in this paper. Some basic propagation properties of vectorial non-paraxial elliptical Gaussian beams, including the irradiance distribution, phase term, beam widths and divergence angles are studied. Numerical results are given and illustrated. 相似文献
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Propagation of circular and elliptical anomalous hollow beams in a turbulent atmosphere is investigated in detail. Based on the extended Huygens–Fresnel integral, analytical formulae for the average irradiance of circular and elliptical anomalous hollow beams propagating in a turbulent atmosphere are derived. The irradiance and spreading properties of circular and elliptical anomalous hollow beams in a turbulent atmosphere and in free space are studied numerically. It is found that circular and elliptical anomalous hollow beams at short propagation distance in turbulent atmosphere have similar propagation properties to those of free space, while at long propagation distance, circular and elliptical anomalous hollow beams eventually become circular Gaussian beams in a turbulent atmosphere, which is much different from their propagation properties in free space. The conversion from an anomalous hollow beam to a circular Gaussian beam becomes quicker and the beam spot spreads more rapidly for a larger structure constant, a shorter wavelength and a smaller waist size of the initial beam. 相似文献
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An alternative theoretical model named partially coherent hollow elliptical Gaussian beam (HEGB) is proposed to describe a partially coherent beam with an elliptical dark hollow profile. Explicit expression for the propagation factors of a partially coherent HEGB is derived. Based on the generalized Collins formula, analytical formulae for the cross-spectral density and mean-squared beam width of a partially coherent HEGB, propagating through a paraxial ABCD optical system, are derived. Propagation properties of a partially coherent HEGB in free space are studied as a numerical example. 相似文献
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A. Ruiz De la Cruz A. Ferrer J. del Hoyo J. Siegel J. Solis 《Applied Physics A: Materials Science & Processing》2011,104(2):687-693
In this work, we report a model for accurately calculating the focal volumes corresponding to astigmatic elliptical beams
used in fs-laser waveguide writing. The model is based on the use of the ABCD matrix formalism for the propagation of a Gaussian beam. The code includes the effects of propagation on the astigmatic elliptical
beam, and the effects of beam truncation and diffraction at the entrance pupil of the focusing objective due to beam clipping
when overfilling the pupil. The results predict that for a given astigmatism value and propagation distance it is possible
to efficiently suppress the astigmatic focus closer to the surface. This explains previous experimental results where single
structure waveguides with controllable aspect-ratio were fabricated using astigmatic-elliptical beams. Furthermore, we investigate
the respective roles of astigmatism and beam propagation, as well as the strong impact of truncation and diffraction effects
caused by clipping the beam at the pupil of the focusing optics. Finally, based on the results from our model, we present
some practical considerations in terms of beam propagation and phase wrapping constraints. 相似文献
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The propagation of elliptical Gaussian beam passing through paraxial optical systems with aperture is investigated analytically by using tensor method. The approximate formula for propagation of elliptical Gaussian beam through hard apertured optical systems is derived based on the fact that the circ function can be expanded into a finite sum of complex Gaussian functions. The derived formula provides a convenient tool for treating the propagation and transformation of elliptical Gaussian beam through apertured optical systems. As an application example, the propagation properties of elliptical Gaussian beam through apertured fractional Fourier systems are discussed. 相似文献
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Chongwei Zheng 《Optical and Quantum Electronics》2006,38(15):1237-1244
A new kind of laser beam named off-axis elliptical flat-topped beam is proposed. This beam is expressed as a finite series
of off-axis elliptical Gaussian beams with different beam parameters. Analytical propagation formulas for the off-axis elliptical
flat-topped beam through aligned and misaligned optical systems are derived. As a numerical example, the propagation properties
of the off-axis elliptical flat-topped beam in free space are calculated and discussed. 相似文献
11.
Zhixiao Chen 《Optics Communications》2011,284(13):3183-3191
We investigate the linear propagation of a paraxial optical beam in anisotropic media. We start from the eigenmode solution of the plane wave in the media, then subsequently derive the wave equation for the beam propagating along a general direction except the optic axes. The wave equation contains a second-order mixed derivative term originating from the anisotropy, and this term can result in the rotation of the beam-spot. The rotation effect is investigated by solving analytically the wave equation with an initial elliptical Gaussian beam for both uniaxial and biaxial media. For both media, it is found that there exists a specific direction, which is dependent on anisotropy of the media, on the cross-section perpendicular to propagation direction to determine the rotation of the beam-spot. When the major axes of the elliptical beam-spot of the input beam are parallel to the specific direction, the beam-spot will not rotate during propagation, otherwise, it will rotate with the direction and the velocity determined by input parameters of the beam. 相似文献
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Average intensity and spreading of an elliptical gaussian beam propagating in a turbulent atmosphere
An analytical formula for the average intensity of an elliptical Gaussian beam (EGB) propagating in a turbulent atmosphere is derived. The spreading properties of an EGB in a turbulent atmosphere are studied. It is found that an EGB will eventually become a circular Gaussian beam in a turbulent atmosphere. This interesting phenomenon is quite different from the propagation of an EGB in free space. The evolution properties are closely related to the parameters of the beam and the turbulent atmosphere. 相似文献
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Based on the fact that a hard-edged elliptical aperture can be expanded approximately as a finite sum of complex Gaussian
functions in tensor form, an analytical propagation expression for an elliptical cosh-Gaussian beam (EChGB) truncated by an
elliptical aperture and passing through an axially nonsymmetrical optical system is obtained by use of vector integration.
Furthermore, the analytical propagation expression for a truncated off-axial EChGB is derived as an application example. Some
numerical simulations are given to illustrate the propagation properties of EChGBs and off-axial EChGBs passing through a
free space with an elliptical aperture.
PACS 41.85.Ew; 42.60.Jf; 42.25.Bs 相似文献
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The propagation formulae of elliptical Gaussian beam through misaligned optical systems in spatial domain and spatial-frequency domain are investigated analytically by using tensor method. The derived formulae provide a powerful tool for treating the propagation and transformation of elliptical Gaussian beam through misaligned optical systems. As an application example, the propagation properties of elliptical Gaussian beam through a misaligned thin lens are illustrated. 相似文献
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Chongwei Zheng 《Optik》2005,116(12):563-567
Based on a tensor method, the propagation formulae of elliptical flat-topped beam through aligned and misaligned optical systems in spatial-frequency domain are derived analytically. The derived formulae provide a powerful tool for treating the propagation and transformation of elliptical flat-topped beam through complex optical systems in spatial-frequency domain. As a numerical example, the propagation properties of elliptical flat-topped Gaussian beam in free space are studied in spatial-frequency domain. 相似文献
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I. Ogawa T. Idehara M. Pereyaslavets W. Kasparek 《International Journal of Infrared and Millimeter Waves》1999,20(4):543-558
Gaussian optics can be used to design a quasi-optical system converting the TE06 mode output (f=388 GHz) of a submillimeter wave gyrotron into a well-collimated, linearly-polarized free-space beam with a circular cross-section. A quasi-optical antenna produces a main beam with an elliptical cross-section, which is then converted by two mirrors into a well-collimated beam with a circular cross-section. 相似文献
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A decentered flattened Gaussian beam (DEFGB), is defined by a tensor method. The propagation formula for a DEFGB passing through an axially nonsymmetrical paraxial optical system is derived through vector integration. The derived formula can be reduced to the formula for a generalized decentered elliptical flattened Gaussian beam under certain condition. As an example application of the derived formula, the propagation characteristics of a DEFGB in free space are calculated and discussed. As another example we have studied the properties of superposition with radial array consisted by DEFGB. 相似文献
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本文采用分步相位屏方法来仿真椭圆涡旋光束在海洋中的实际传输情况,并对椭圆涡旋光束在海洋湍流中的传输光强和闪烁因子进行了仿真。研究发现,椭圆涡旋光束在海洋传输过程中,光斑会发生明显的旋转,同时光斑会产生暗核且暗核个数与光束的拓扑荷数相等。一个拓扑荷数为m的相位奇点会分裂成m个拓扑荷数为1的相位奇点,并且海洋湍流越强,光斑受到的干扰越严重。研究还发现,在较弱的海洋湍流中,随着传输距离的增加,椭圆涡旋光束的闪烁因子会低于高斯光束和涡旋光束的闪烁因子,而且在远距离处拓扑荷数越大闪烁因子降低越明显,同时也发现,传播一段距离后涡旋光束的闪烁因子会低于高斯光束的闪烁因子。在较强湍流中,椭圆涡旋光束的闪烁因子会交叠在一起。对于不同强度的海洋湍流,随着均方温度耗散率的增大,椭圆涡旋光束的轴上点闪烁因子也增大。在同一传输距离处,束腰宽度越小的椭圆涡旋光束闪烁因子越小。 相似文献