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.     

Determination of Tungsten Layer Profiles in Bilayer Structures Using X-Ray Reflectivity Method

An effectual method is presented to determine the profiles of a tungsten （W） layer, such as the density, the thickness and the roughness in the multilayer structures, using the x-ray reflectivity technique. To avoid oxidation effects of tungsten, a B4 C capping layer is deposited onto to the W layer. To observe the profiles of the tungsten layer with different thicknesses, three groups of W/B4 C bilayers with different thicknesses are prepared by using ultra high vacuum dc magnetron sputtering and measured by an x-ray diffractometer. A type of genetic algorithm called the differential evolution is used to simulate the measurement data so as to obtain the parameters of bilayers. According to the simulation, it is shown that the W layer density varies from 95.26% to 97.51% compared to the bulk. In our experiment, the deposition rate is 0.044 nm/s, and the thickness is varied in the range of 9.8-19.4 nm.     

光信息科学与技术专业实验室建设探讨

根据同济大学光信息科学与技术专业的教学计划,同时结合我校的科研条件,筹建了相应的专业实验室。介绍了同济大学光信息科学与技术专业实验室建设过程中的规划和7类实验项目的内容和意义,如光谱学系列实验、光学系统CAD设计系列、光学薄膜CAD设计系列、光学薄膜特性测试实验、激光系列实验、光电基础和光电探测系列实验和光纤光学与光纤通信系列实验。     

基于时间控厚离子束溅射技术的宽带减反膜制备

 为了制备满足设计要求的宽角度、宽波段减反膜,利用离子束溅射沉积技术,在时间-功率控厚的模式下,对膜层沉积速率进行了精确修正。在实验中,利用时间-功率控厚的离子束溅射沉积技术,选择HfO₂和SiO₂作为高低折射率组合,在超抛ZF6玻璃基底上制备了宽角度、宽带减反膜,通过对实验后的透过率光谱曲线的数值反演计算,获得膜层厚度修正系数,初步得到了沉积速率随沉积时间变化的规律。利用修正后的沉积参数制备设计的膜系,在0°~30°入射角度下,600~1 200 nm波段的平均透过率达到99%以上。     

Crystal growth and spectral properties of Tb:Lu_2O_3

The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb:Lu_2O_3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10~(-22)cm~2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt(J-O)intensity parameters ?_2,?_4,and ?_6 were computed to be 3.79×10~(-20)cm~2,1.30×10~(-20)cm~2,and 1.08×10~(-20)cm~2,with a spectroscopic quality factor ?_4/?_6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10~(-22)cm~2 and 1.32×10~(-22)cm~2,respectively.The fluorescence lifetimeτexp of ~5D_4 was fitted to be 1.13 ms.The data suggest that the Tb:Lu_2O_3 crystal could be a potential candidate for green and yellow laser operation.