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1.
In this paper, we present the validity of in-line-type differential push-pull methods using segmented gratings with respect
to the radial shift of an objective lens by numerical calculation for the first time. In these differential push-pull methods,
the segmented gratings for generating sub spots are divided into two to four regions each with a specific phase value and
a width. Tracking error signals are calculated with respect to the objective lens shift under parameter conditions of the
widths of the segmented regions. The obtained results show that the grating of the simpler configuration with two regions
reveals good compatibility between DVD-R and DVD-RAM compared with those with three or four regions 相似文献
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A comparison of the optical path and differential equation methods for optically thin phase gratings
It is shown that the optical path method may lead to an approximate solution of the wave equation valid under a wide range of conditions for slanted phase gratings of arbitrary profile. Analytic solutions are given for sinusoidal and sawtooth gratings, and the accuracy of the approximations is checked by comparison with numerical solutions. The conditions under which sawtooth gratings may yield 100% efficiency are clarified. 相似文献
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分析了两种光栅拼接调整机构(三角形和L形),利用有限元分析软件对这两种光栅调整机构进行了模态分析和优化分析设计。相同光栅尺寸下(以口径为450 mm420 mm60 mm光栅为例),驱动器三角形分布的固有频率与L形分布的固有频率相差无几,一阶频率分别为58.816 Hz和58.864 Hz。对两种驱动器布置方式引入的误差进行了分析比较,计算结果表明:三角形调整机构的最大误差比L形的大,同时三角形分布控制算法较L形的复杂。在主动控制中三角形模型误差迭代次数多,不利于控制。因此L形的压电驱动器布置方式优于三角形。 相似文献
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The filter characteristic of NRD waveguide grating is investigated rigorously by combining network approach with mode matching theory. Numerical examples are shown and compared with experiment results.This work was supported by National Natural Science Foundation of China. 相似文献
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The antireflection properties of triangular shaped gratings are studied by a combination of the effective medium theory and the anisotropic thin-film theory. The triangular shaped structures are analyzed as a function of grating period, filling factor, and groove depth, and the antireflective characteristics are also studied when visible-infrared light is incident upon them. Numerical examples are given for gratings on glass substrate with refractive index of 1.5. The results show that this kind of grating is capable of reducing reflections, and could achieve very low reflectivity over a wide field of view and a wide waveband by choosing appropriate parameters. 相似文献
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Planar (co)sinusoidal conductivity (absorption) transmission gratings are analyzed using rigorous coupled-wave theory. The first-order and higher-order diffraction efficiencies are determined over the entire range of possible conductivities and Bragg angles of incidence (or equivalently, grating periods) for H-mode polarization incident plane waves. The maximum possible first diffracted order efficiency is found to be 5.26%. Rigorous results are compared to approximate results from the Raman-Nath theory and the two-wave first-order coupled-wave (Kogelnik) theory. A regime parameter, , is defined which delineates the regions of Raman-Nath diffraction behavior ( < 1) and the region of two-wave first-order diffraction theory behavior ( > 1). Likewise, the angular selectivity characteristics of conductivity gratings are determined from rigorous theory and are compared with corresponding results from approximate theory. 相似文献
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利用傅里叶光学方法,建立了一个基于远场的高斯光束数学模型.该模型能够分析单程拼接光栅压缩池系统中拼接光栅的缝隙对远场时空特性的影响.数值模拟得到了不同系统参数时远场时空特性关于缝隙宽度的变化曲线.揭示了光栅缝隙对远场的影响规律:对于双光栅拼接的压缩池系统,若只是压缩池中第二块光栅为拼接光栅,则光栅缝隙导致远场时域略微变窄;若压缩池中的两块光栅都是拼接光栅,则缝隙导致远场时域展宽或者变窄,依赖于入射脉冲的傅里叶变换极限型脉宽大小;光栅缝隙对于远场强度分布的影响是导致中央主峰能量下降,并且出现两个子峰,子峰的峰值随缝宽的增大而增大. 相似文献
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Propagation characteristics of a segmented cladding fiber 总被引:3,自引:0,他引:3
We propose a novel optical fiber design that consists of a uniform core and a segmented cladding formed by alternate regions of high and low refractive indices in the azimuthal direction. The structure is analyzed by use of the radial effective-index method, and the propagation characteristics of the structure are studied. The fiber has a highly dispersive cladding and shows characteristics similar to those of photonic-crystal fibers and holey fibers. The novel fiber offers the possibility of single-mode operation over a wide range of wavelengths with a large core diameter. 相似文献
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S. M. Sikach 《Physics of Atomic Nuclei》2005,68(6):1064-1070
A covariant method for calculating reaction amplitudes in the diagonal spin basis is presented. In this basis, amplitudes represent the spin kinematics of the interacting particles in the simplest and most adequate manner. A matrix is obtained such that differential cross sections for polarized particles and amplitude combinations that are required to calculate various polarization characteristics of reactions can be expressed in an arbitrary basis in terms of the amplitudes calculated in one basis. 相似文献
16.
根据高密度光盘参数 ,计算了聚焦光斑在光盘表面扫描过程中每个位置的光瞳光强分布 ,得到DPD(Differ entialPhaseDetection)循轨误差信号。考虑盘片的径向倾斜 ,在光瞳光强分布方程中引入盘片的径向倾斜角度参数 ,计算了高密度盘片产生径向倾斜时DPD循轨误差信号的变化 ,进而分析了盘片的径向倾斜引入的循轨伺服误差及其对循轨伺服的负面影响。结果表明 ,高密度盘片产生 0 .5°的径向倾斜相当于引入了 0 .0 12 μm的循轨误差 相似文献
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基于Kogelnik理论模型,以平面波为入射光,分析了双体布拉格光栅(VBG)的反馈特性。理论分析表明,采用双VBG结构,通过控制两个VBG的中心波长差,可以使光栅反馈的效率提高,带宽加宽。对于由两块带宽100 pm、衍射效率20%的VBG组成的双VBG反馈系统,中心波长相同时,衍射效率最大(33.3%);中心波长相差84 pm时,其带宽为单VBG带宽的1.8倍(180 pm)。由于VBG的中心波长存在温度漂移特性,因此通过改变双VBG结构中VBG的温度可以实现衍射效率和带宽的改变,为泵浦源的优化提供有效可行的方法。 相似文献
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基于Kogelnik理论模型,以平面波为入射光,分析了双体布拉格光栅(VBG)的反馈特性。理论分析表明,采用双VBG结构,通过控制两个VBG的中心波长差,可以使光栅反馈的效率提高,带宽加宽。对于由两块带宽100 pm、衍射效率20%的VBG组成的双VBG反馈系统,中心波长相同时,衍射效率最大(33.3%);中心波长相差84 pm时,其带宽为单VBG带宽的1.8倍(180 pm)。由于VBG的中心波长存在温度漂移特性,因此通过改变双VBG结构中VBG的温度可以实现衍射效率和带宽的改变,为泵浦源的优化提供有效可行的方法。 相似文献
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针对大口径望远镜拼接式主镜,提出一种基于迈克尔逊干涉原理的低相干光谱干涉检测系统.应用该系统对拼接子镜间相位失调误差进行实时检测,进而对失调子镜进行相应校正,以实现拼接子镜的共面排布.子镜间相位误差通过干涉图形间的不匹配性进行提取.给出了该低相干光谱干涉检测系统的具体结构,叙述了该干涉检测系统的检测原理.针对该系统的干涉条纹对比度V及系统的最低信噪比SNRdBmin进行了分析,论证了通过该低相干光谱干涉检测系统进行子镜间相位误差检测的可行性. 相似文献