查询词典 diffraction

According to the diffraction theory used in DVD system, we propose a new theory to analyze the RF signal and tracking error signal of Super-RENS disk. Then we use simulate the tracking error signal under beam aberration. Finally we use FDTD method to simulate the tracking error signal at defocus.

我们亦根据传统光碟片的绕射理论，提出一新的架构用於分析此近场结构，并用此理论进行射频及偏轨信号的模拟；接著探讨在有像差产生的情形下，其对偏轨信号的影响，最后用有限时域差分法验证在失焦下，偏轨信号的变化。

Space optical system, especially space infrared optical system, cryogenic optical system and some huge space-based telescopes, all work in the environment where there is strong radiation (such as Sun etc.) out of the field of the system. Because of diffraction of the entrance pupil and diffuse scatter of all inner surfaces, the strong stray radiation will reach the detector of the system.

空间光学系统，特别是空间红外光学系统、低温光学系统以及某些大型空间望远镜，都工作在系统视场外有强烈辐射源的&恶劣&环境中，这些强烈杂光辐射经过光学系统孔径的衍射，以及结构与光学件表面的散射，到达系统像面形成杂光。

In chapter four,based on diffraction theory,we derived the far field intensitydistributions near geometric focus for off-axis Gaussian and uniform beams passing througha primary aberrated optical system.

在第四章中，基于衍射理论，推出了离轴高斯光束和均匀光束通过一个初级球差光学系统后，其几何焦点附近的远场光强分布公式。

The second-harmonic generation theory of phase aberrated laser beam in uniaxial crystals is discussed, in cluding the effects of diffraction and transverse walkoff.

理论上研究了单轴晶体Ⅰ类匹配时相位畸变光束二次谐波的转换，其中考虑了衍射、离散效应，给出了相位畸变小信号解。

This problem is also important and valuable in Nonlinear Optics. It will be very helpful to understand how the aberrations affect the course of three- wave mixing, such as the change of conversion efficiency, the distribution of intensity and phase.Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental waves aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立国防科学技术人学研究生院学位论文三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼一夏克传感器分别对IO64nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental wave's aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼-夏克传感器分别对1064nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

Characterization of cotton fiber using solid-state ~(13)C-CP/MAS NMR spectroscopy shows that the crystallinity after MHT is lower than the original sample,but the cotton after MHT has a higher lateral orientation index,which has a good definition in C2,3,5 resonance region.~(13)C-CP/MAS NMR spectroscopy and X-ray diffraction reveal that cellulose I_βis the main cellulose in cotton,and microwave change the allomorphs content.

通过核磁共振碳谱表征分析可知，微波处理之后的结晶度要小于原样，但是由于微波处理之后的棉纤维有相当高的侧向有序指数，其在C2，3，5共振区域有更好的清晰度。X衍射和核磁共振均表明棉纤维是以纤维素I_β为主，微波处理改变了纤维素的晶型，晶型含量I_α和I_β均降低，但是比例基本保持不变，微波处理之后向次晶转化。

Quasi-near field spots with a profile of sharp edge and flat top can be obtained with a diffraction-weakened lens array, while the speckles imposed on the spot by beamlets interference can be smoothed by spectral dispersion.

消衍射型透镜列阵能获得边缘陡峭且顶部较平坦的准近场焦斑，光谱色散平滑则能有效地抹平焦斑内部由多光束干涉引起的细密条纹。

A chiral phase transfer catalyst, N-benzyl quinine bromide, was synthesized from natural chiral compound. And 2,5-bimethyl-4-(3-nitrobenzene)-1,4-bihydrogenation pyridine-3--4-methyl formate (viz. nitrendipine) was synthesized by this chiral phase transfer catalysis, and characterized by elemental analysis, infrared spectrum,1H nuclear magnetic resornace, and X-ray single-crystal diffraction.Key words: ammonium; chiral phase transfer catalyser; crystal structure

通过对天然手性物质进行修饰合成手性相转移催化剂N-苄基溴化奎宁，并对目标分子2，5-二甲基-4-(3-硝基苯)-1，4-二氢吡啶-3-甲酸乙酯-5-甲酸甲酯进行不对称催化合成，并通过红外光谱和核磁共振氢谱对化合物进行了表征，用X射线单晶衍射法测定了该化合物的晶体结构。

Diffraction ; beam current distribution ; design of deflectors

衍射；束流分布；偏转器设计

You can do some assertiveness training.

你可以进行一些自信训练。

We were well on the path to making a rear-wheel-drive global platform," says Mays."

我们正致力于建立一个后轮驱动的平台，"Mays这样说道。"