光栅

The main works include: In this thesis, we use Finite Difference Time Domain method to study the relationship between diffraction efficiency, angular dispersion and grating constant, to discuss how the grating figure influence the diffraction efficiency, and to research the frequency spectrum characteristic.

主要工作包括：本文分别在垂直入射和自准直入射（光垂直于光栅刻槽面入射）情况下，采用时域有限差分方法，利用商业数值计算软件OptiFDTD对二维闪耀光栅进行了矢量电磁场数值计算，研究了光栅的衍射效率和角色散随光栅常数的变化情况，研究了光栅形状对光栅衍射效率的影响，还讨论了各种光栅的频谱特性。

The said Martinez stretcher comprises concave spherical reflecting lens, plane reflecting lens and grating. The said compressor comprises plane reflecting lens, inner right angle reflecting lens and grating, which is characterized by the following: the grating fringe density of the stretcher is larger than that of the compressor.

所述的马丁内兹展宽器由凹球面反射镜、平面反射镜和光栅组成；所述的压缩器由平面反射镜、内直角形反射镜和光栅组成，其特征在于，展宽器的光栅条纹密度大于压缩器的光栅条纹密度；展宽器中的凹球面反射镜曲率半径位0.9～1.2米，光栅距凹球面反射镜的位置为凹球面反射镜曲率半径的1/3～1/2。

We expect it will benefit the industry field to break through the optical measuring limits at present by offering some new ideas. Optical measuring research based on moire interferometry has developed for several decades. The main idea of this research is to utilize the moire effect caused by two superimposed gratings of identical or similar spatial frequency. One is the reference grating and it is a virtual grating created by a computer program in this research; The other grating is the image of grating projected on the measured surface by the DLP projector, and this grating will distort because of the different sloped profile of the surface. To superimpose the program-created grating and the captured distorted grating will derive the so-called moire effect. This research combined the basic theory of optical interferometry and moire effect to project the different phases of the projected grating fringes by the phase-shifting method and compute the principal value of arguments between -π,π. In the end, the phase unwrapping program based on discrete Fourier transform of solving PDEs is used to unwrap the phase of the measured surface, and finally the surface profile is derived by the optical measuring system.

以叠纹干涉术为基础的光学检测研究之发展早已行之有年，而在本研究中所采用的投影叠纹法(Projection moiré)之主要精神在於藉由两道空间频率相近或相同的光栅相互叠加而成的效应，其中一道为参考光栅，而本研究中的参考光栅是以程式产生可调整不同空间频率的虚拟光栅；另一道则为投影至待测物表面的光栅影像，而在起伏高度不一的待测表面上的光栅影像会受到待测物表面起伏状况不同而在观测方向产生光栅投影条纹影像的歪曲变形，将电脑产生的参考光栅与由影像撷取装置所获取投影於待测物表面的光栅影像作叠合，便会产生所谓的叠纹效应；利用基本的光学干涉理论与叠纹效应结合，本研究中以相移法来改变投影於待测表面的光栅相位，再以相移法的理论反运算出在带有待测面各点高度资讯之介於-π，π相位主幅角，再以离散傅立叶转换解偏微分方程的相位重建程式还原待测面的相位值，以得知待测面之表面轮廓。

Open Linear Encoder includes main grating scale and optical encoder head. This optical encoder head includes LED light source, optical detector module, and secondary phase-grating. LED light will pass through the plano-convex lens and produces parallel light. As the parallel light pass through secondary grating, the quadratic image display on the main grating scale. And the Moire interference will be reflected from the main grating scale and detected by optical detector module, as there is a relative shift between the main and secondary grating. From detecting the periodic sinusoidal signal with phase difference 90°, the period represents the grating pitch, using the counter to detect the number of periodic signals to get the displacement, and we can adapt the technology of electron subdivide further to increase the resolution of measurement .

反射式光学尺包括主光栅尺及光学读头，光学读头包含LED光源、光侦测器模组及相位式副光栅，LED光源经平凸透镜，产生平行光穿透副光栅后，副光栅之二次成像投射在反射主光栅尺上，当主、副光栅因相对运对产生之Moire干涉经主光栅尺反射至光电检测器，检出相位差90°之周期性弦波讯号，其周期代表栅距，因此可用计数器检出周期性讯号数目得到位移量，可进一步采用电子细分割技术提高解析度。

Finally, We analyze and experimentally demonstrate that both the bandwidth of the fiber Bragg grating's short wavelength loss and the bandwidth of fiber Bragg grating's reflection increase with the increase of strain gradient along the length of grating.

最后，我们对光纤光栅的反射和短波损耗的应变特性作了理论分析和实验测试，发现在光纤光栅的反射带宽随光栅轴向应变梯度的增加而增加的同时，光栅短波损耗带宽也随光栅轴向应变梯度的增加而增加。

Besides, the spectrum property of the phase shift LPG with different phase shift in different position and parallel or cascade LPG were also analyzed and studied. The fiber gratings parameter and combination fit for refractivity measure were selected.

此外，还分析和研究了在不同位置引入不同相位跳变的相移光栅、并联长周期光纤光栅以及级联长周期光纤光栅的光谱特性，选择出适用于折射率测量的合理光栅参数及光栅组合方式。

A grating function and a groove function are introduced to determine the structure of a concave grating. Basic ideas for the design of a flat-field concave grating with three stigmatic points are proposed. As a proof of the usefulness of these design approaches, image conditions of the grating with three stigmatic points are developed which concise with other published results and they are more general than those obtained from holographic gratings.

采用与分析三维光栅相类似的级数展开法给出了二维集成凹面光栅的球差、彗差的计算方法，计算中用光栅函数和槽面函数来描述具有任意形状和任意变化周期的光栅，提出了一种具有三个无像差点的平面场型凹面光栅的设计方法，利用该方法推导了三点无像差光栅的成像条件，与文献中用其它方法获得的结果相一致，该结果与全息光栅的成像条件相比，更具一般性。

Beginning with wave equation, the paper has deduced the propagation of gauss pulses in single mode fiber and fiber grating transmission compensation. The characteristics of cascaded phase-shift gratings are discussed by numerical simulations of coupled-mode theory and T-matrix method. The experimental works and measurement results are shown in this paper. On the other hand, we have introduced the basic theory of EDFA and figured out the characteristics for EDFA at different conditions by numerical simulation. Some experimental results for EDFA are also presented here. In this article, you can find the influence on Optical Fiber Amplifier by Gain Tilt, especially, the negative effect on CSO in CATV transmission system.

论文首先从波动方程入手，对高斯脉冲在单模光纤中的传播演化及光纤光栅透射补偿进行了详细的研究；较系统地介绍了光纤光栅的耦合模理论，并将传输矩阵计算法用于计算级连相移光纤光栅的光学特性；重点介绍了作者在光纤光栅刻制及特性测量方面所做的一些实验研究工作；较系统介绍了EDFA的基本理论，计算出各种条件下EDFA的光学特性，并进行了一些实验研究；综合分析光纤放大器对光纤传输系统的影响，特别分析了光纤放大器增益不平坦对光纤CATV系统中CSO恶化的原因及其解决方法，并研究了光纤布拉格光栅在稳定980nm泵浦源输出功率和输出波长方面的应用；结合一个基于光纤光栅和光纤放大器的光纤用户接入网方案，对光纤用户接入网的若干问题进行了理论与初步的实验研究。

Base on the analysis of the grating linear displacement measurement theory,t he measure errors especially the subdivision error of the grating scale,this paper focuses on the theory of switch and merge of dual grating scales'signals,builds the design criteria of high speed high precision displacement measurement by using dual grating sales,designs the switch picking reference with high precision and fast switch and merge method,analyses the errors brought in by switch and merge of the duals grating scales.

针对光栅尺的电子细分信号具有细分误差的特性，本文提出了对莫尔条纹信号不细分的方法以提高双光栅尺信号切换合成值的精度。经过对双光栅计数切换基准、切换与合成特征和规律的探讨，本文设计了实现双光栅尺双重测量、计数值切换合成法的硬件电路，主要通过可编程芯片FPGA，设计了双光栅尺信号处理的各电路模块，如双光栅尺信号四倍频辨向模块、速度判断模块、切换模块、计数值合成处理模块。

In aspect of investigation on the binary phase splitting grating, Dammann grating, rectangle grating and also coordinate-phase modulate grating have been studied respectively. Detail analysis shows that the grating phase angle can inflect greater than coordinate to the splitting efficiency and equality rate.

在对二元位相型光学分束光栅的研究方面，在本论文对Dammann光栅、矩形孔径光栅以及坐标位相调制型光栅分别进行了研究，通过对光栅设计参数的变化对分束效率、分束均匀度的影响的分析可以发现光栅位相角对分束效率及分束均匀度的影响要比突变点坐标的影响大得多。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了