基于遗传算法的30.4 nm多层膜设计

阐述了用遗传算法设计周期和非周期多层膜的原理和实现过程,完成了30.4 nm Mg/SiC周期和非周期多层膜设计,研究了遗传算法中不同种群数和多层膜膜厚取值范围对优化结果的影响.计算发现,种群数的恰当选取是使算法快速达到或逼近最优解的前提,膜厚取值范围的合理选择是提高算法效率的关键.设计得到入射角10°的周期多层膜和15°~22°范围内的宽角多层膜在波长30.4 nm处的反射率依次为56.57%与39.96±0.29%,5°入射的双功能多层膜在波长30.4 nm和58.4 nm处的反射率分别为54.1%和0.1%.结果表明遗传算法也是一种很好的多层膜设计方法.     

同步辐射软X射线多层膜反射偏振元件研究

利用多靶磁控溅射方法分别镀制了W/C和Mo/Si两种周期性结构多层膜。通过对其相关参数周期数、厚度比以及周期厚度的调整,使薄膜的布拉格衍射峰出现在布儒斯特角附近,两种多层膜的应用能量范围分别落于C的近K边处和Si的L边前。在北京同步辐射装置3W1B光束线的软X射线光学实验站上进行了反射率的测量,得到W/C膜的反射率在214eV时达到4.18%;Mo/Si周期性多层膜的反射率在89eV处达到32.3%。根据测量结果,分析了在同步辐射装置作为偏振元件的可行性     

单晶硅化学机械抛光划痕演变研究

化学机械抛光法是制作超光滑单晶硅镜片的常用工艺,抛光过程中的各类杂质粒子经常会导致加工表面产生划痕,降低镜片的表面质量。为系统研究不同晶向单晶硅表面塑性划痕与抛光液中杂质的关系,设计了金刚石微粉掺杂抛光Si(111)、Si(110)和Si(100)晶面的实验。利用轮廓仪测量了不同晶向、不同掺杂浓度下的划痕形貌,并通过计算载荷归一化后的划痕宽度分布、划痕深度分布、粗糙度和二维功率谱密度来评估划痕形貌。结果显示,抛光液中杂质粒子粒径、硅片表面的划痕宽度均服从正态分布。随着杂质粒子浓度的增加,划痕形貌从非周期性特征转变为周期性波动,粗糙度出现突跃点。此外,在同浓度金刚石微粉掺杂情况下,Si(110)面在划痕产生初期有更好的杂质粒子容忍度。     

2.5 keV能点多层膜KB显微镜成像性能

研究了Kirkpatrick-Baez（KB）显微镜成像系统的结构设计、元件制备。通过分析掠入射角、放大倍数和反射镜曲率半径对成像系统调制传递函数（MTF）的影响,确定了KB显微镜系统的初始结构参数,实现了2.5 keV能点多层膜KB显微镜的设计、制备以及装调,在神光Ⅱ强激光装置上完成了像质标定实验。结果表明:2.5 keV能点多层膜KB显微镜在100 m视场内观测周期为20 m平面调制靶时的MTF高于0.6,与OMEGA装置同类型KB系统的空间分辨能力相当,明显优于现有的针孔相机和点投影成像技术。该显微镜与条纹相机配合,已成功实现对短扰动波长平面调制靶烧蚀演化行为的动态诊断。     

Optimization of geometrical design of nested conical Wolter-I X-ray telescope

Optical design of nested conical Wolter I X-ray telescope covering energy band from 1 to 30 keV is investigated systematically. Recurrence relation of the nested structure is deduced, and the impact of the initial parameters on the performance is analyzed. Due to the need for hard X-ray astronomical observations in China, the initial structure is presented, for which six groups of W/B4C aperiodic multilayer coatings between the innermost and the outermost shell of the mirror are designed. The effective area, resolution, and field of view are calculated in the simulation. The results show that the effective area can achieve 71 cm2 and the field of view can achieve 13 at 30 keV. The resolution is estimated to be ～10 in half-power diameter.     

Output regulation for linear multi-agent systems with unmeasurable nodes

The output regulation of linear multi-agent systems with partial unmeasurable agents is investigated in this paper. All the agents except the exosystem can be classified into two groups. Agents in the first group can be measured by themselves and their neighbors. State variables are not fully accessible for direct communication and full order Luenberger observers are constructed for the unmeasurable agents. We give a state feedback control law to solve the output regulation problem under the communication topologies based on both measurable and unmeasurable agents. The heterogeneous agents’ synchronization problem is a general case of our results. Finally, examples are utilized to show the effectiveness of the obtained results.     

一维光子晶体的双通道位置设计及调整

通过对法布里-珀罗滤光片性质的研究,以及对法布里-珀罗滤光片中缺陷层厚度变化对通道数目、位置影响的分析,为双通道一维光子晶体的设计提出了一条新的思路。在法布里-珀罗结构的基础上引入一维光子晶体的双对称结构,并通过改变双对称结构的三个缺陷层厚度来实现对禁带内两个通道系列位置的独立调整。设计过程中采用有效界面法对通道的位置进行初步的计算,并通过计算机理论模拟对膜层进行修正,使通道的位置满足设计要求。设计结果表明,通过调整两个厚度参量可以克服双通道一维光子晶体中的通道干涉现象,从而实现通道位置的独立调整。     

Influence of Small-Size Contaminations on Thin Film Structural Properties

An approach for studying the influence of nano-particles on the structural properties of deposited thin films is proposed. It is based on the molecular dynamic modeling of the deposition process in the presence of contaminating nano-particles. The nano-particle is assumed to be immobile and its interaction with film atoms is described by a spherically symmetric potential. The approach is applied to the investigation of properties of silicon dioxide films. Visualization tools are used to investigate the porosity associated with nano-particles. The structure of the film near the nano-particle is studied using the radial distribution function. It is found that fluctuations of film density near the nano-particles are essentially different in the cases of low-energy and high-energy deposition processes.     

亚飞秒啁啾Mo/Si多层膜反射镜的设计、制作与性能检测

针对利用高次谐波获取亚飞秒脉冲的实验需求,设计制备了啁啾为-2 800 as2的啁啾Mo/Si多层膜反射镜.数值计算表明,采用所设计的啁啾多层膜反射镜可以获得86 as的脉冲.通过直流磁控溅射方法实现了Mo/Si多层膜样品的制备.在合肥同步辐射上进行了多层膜反射率的测量,在所设计的工作波长内,多层膜的平均反射率为5.6±2.3%.在考虑最上层Si的氧化作用后,对测量曲线进行拟合,得到的反射率曲线和膜层厚度分布分别与测试曲线和设计结果相吻合.     

Study of X-ray Kirkpatrick-Baez imaging with single layer

The X-ray Kirkpatrick-Baez （KB） imaging experiment with single layer is implemented. Based on the astigmatism aberration and residual geometric aberration of a single mirror, a KB system with 16^x mean magnification and approximately 0.45°grazing incidence angle is designed. The mirrors are deposited with an Ir layer of 20-am thickness. Au grids backlit by X-ray tube of 8 keV are imaged via the KB system on scintillator charge-coupled device （CCD）. In the ±80 #m field, resolutions of less than 5 #m are measured. The result is in good agreement with the simulated imaging.