共查询到20条相似文献,搜索用时 62 毫秒
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光盘光学系统的矢量衍射理论分析 总被引:5,自引:3,他引:2
本文以完整的矢量衍射理论分析了光盘光学系统。首先将入射的聚焦光束分解为平面波谱 ,得到每个平面波的振幅矢量 ;然后计算光盘对每个平面波的衍射 ,得到衍射波的振幅矢量 ,从而得到了整个衍射波场的空间频谱 ;最后计算物镜光瞳上的能通量 ,得到光盘系统的读出信号。在衍射计算中 ,光盘被定义为二维金属光栅 ,根据信息符的不同模型 ,选用坐标变换方法、耦合波方法或模态方法。对于典型的 DVD光学系统来说 ,矢量理论的结论与标量理论相差甚远 ,要得到正确的结果就必须采用矢量衍射理论 相似文献
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对称面形光栅TE模的衍射特性 总被引:3,自引:1,他引:2
本文采用耦合波方法计算了对称面形光栅的衍射效率,分析了光栅截面面形为正弦、三角形、矩形、梯形光栅衍射效率与光栅周期、沟槽深度的关系,计算了光栅的峰值衍射效率。理论计算表明:合理地选择光栅周期、沟槽深度,对称面形光栅都可以达到很高衍射效率,接近100%;光栅的峰值衍射效率基本出现在Bragg衍射且光栅的周期等于衍射波长时。 相似文献
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Diffraction gratings: aberrations and applications 总被引:1,自引:0,他引:1
Diffraction grating is an optical instrument, which is advantageously used for scientific research in spectroscopy and spatial filtering. It has many other applications in science and technology such as wavelength selectors for tuneable lasers, selective surfaces for solar energy, masks for photolithography, beam sampling mirrors for high power lasers, spectrometers in extreme UV and X-ray regions for space optics, metrology, phase measuring interferometry and pattern recognition, etc. Although the holographic gratings have many advantages over the ruled gratings but they have not yet eliminated completely the classical ruled gratings as the ruled gratings have their own importance in many applications. Therefore, in this article, both the ruled and holographic gratings will be discussed, in particular, their focusing properties, aberrations, and their applications. 相似文献
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Fourier modal method incorporating staircase approximation is used to study tapered crossed subwavelength gratings in this paper. Three intuitive formulations of eigenvalue functions originating from the prototype are presented, and their convergences are compared through numerical calculation. One of them is found to be suitable in modeling the diffraction efficiency of the circular tapered crossed subwavelength gratings without high absorption, and staircase approximation is further proven valid for non-highly-absorptive tapered gratings. This approach is used to simulate the ``moth-eye' antireflection surface on silicon, and the numerical result agrees well with the experimental one. 相似文献
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凹面光栅因同时具有聚焦和色散功能而广泛应用于各类紫外、可见和红外波段的光谱分析仪器中,尤其是平场凹面光栅可以结合线阵或面阵探测器来实现即时分析。凹面光栅衍射效率的高低直接影响光谱仪器的信噪比和信号采集,其相关研究也逐渐为人们所关注。介绍了凹面光栅衍射效率的研究进展,比较了由机械刻划法和全息法制作的凹面光栅在掠入射下衍射效率的差别,分析了现有计算衍射效率方法的优缺点,并且对凹面光栅衍射效率的研究趋势做了简要预测,提出了需要同时在凹面光栅的主截面和非主截面内考虑光束对其衍射效率的影响。 相似文献
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Three features about the intersecting state of two gratings are used to identify dot-matrix holograms created by two-beam writers in this paper. The first feature is the intersection angle of the fringes of two gratings. The second feature is the ratio of the pitches of two lowest-order moiré-patterns formed by overlapping two gratings. The third feature is the length ratio of the two diagonal lines of a parallelogram constructed by two neighboring fringes of a first grating and two neighboring fringes of a second grating. All the three features are equivalent, i.e. they are all relative to the intersection angle of two gratings. Because the grating orientations of grating dots cannot be accurately reproduced for the orientation uncertainties of the components used by a two-beam writer, the intersection angles of the gratings of grating dots cannot be easily counterfeited. Therefore, the proposed methods are practical and feasible for the anti-counterfeiting applications of dot-matrix holograms. 相似文献
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间隔叠合式双层亚波长光栅 总被引:1,自引:0,他引:1
提出了一种应用价值较高的防伪光栅结构-间隔叠合式双层亚波长光栅,可以展宽基本光栅的光谱峰值带宽、改善光谱线形和光变效果.分析了亚波长光栅光谱峰值带宽展宽和线形改善的原理,用矢量衍射理论验证了理论分析的合理性,并对特定防伪光变设计要求的双层光栅进行了参量优化和光变特性分析.结果表明,满足同相位条件的光谱线形与基本光栅相同,带宽为基本光栅的两倍;满足反相位条件的光谱线形为准矩形,带宽大于基本光栅;亚波长光栅在传统和非传统照明条件下倾斜均能产生彩色光变效果,且传统照明情况下的光变速率较大,利用这种光变速率差可以制作各向异性光变效果. 相似文献
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The diffraction efficiencies of pure absorption gratings are investigated in photographic materials using a coupled multiwave analysis with a realistic photographic film model. It is, for example, shown that the maximum efficiency of the order +1 of non-sinosoidal absorption gratings is almost independent of the generally used regime indicator Q′. Examples of diffraction characteristics for thin absorption gratings are included. 相似文献
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Hybrid technique of finite element method (FEM) and Gaussian mode expansion method is implemented for the analysis of transmission
property of dielectric phase gratings used in holographic power combining systems. It takes advantages of the versatility
of FEM and the simplicity of the mode expansion method. Apparently, this hybrid method is well suited for the analysis of
phase gratings with complex profiles, which provide more degrees of structural freedom than those of classical rectangular
groove gratings. The transmitted fields of an array of two and three fundamental Gaussian beams through the multi-stepped
and curved gratings are calculated by the hybrid method. Numerical results show that much less phase distortion can be fulfilled
for the reconstructed pseudo-plane wave by the modified phase gratings, especially the curved ones. This is advantageous for
improving the combining efficiency in spatial millimeter wave and sub-millimeter wave power combining systems. 相似文献