基于平板波导的小型红外光栅光谱仪光学设计

为实现红外光谱仪器的小型化,通过分析现有小型光谱仪,提出了一种基于平板波导的小型红外光栅光谱仪的设计方法。平板波导光谱仪的小型化原理与一般的微小型光谱仪不同。在平板波导光谱仪中,光束被限制在一层薄薄的平板波导介质中传播,看起来像是整个光学系统被压扁了。在垂直于平板波导的方向上光学元件的尺寸可以做到很小,从而显著减小光学系统的尺寸。该系统的设计可分为Czerny-Turner结构设计、波导结构设计。先根据像差理论设计Czerny-Turner结构,目标是保证光谱分辨率及校正像差;然后根据几何光学理论设计波导结构,包括平板波导和两个柱面透镜,目标是压缩光束并校正像散;最后将它们输入Zemax软件中进行综合优化,以获得最优的光学系统。据此方法设计了一个平板波导红外光栅光谱仪,工作波段为8~12 μm,数值孔径为0.22,采用线阵探测器。通过Zemax软件对结果进行分析和评价,表明仪器光学系统的尺寸为130 mm×125 mm×20 mm,工作波段内光谱分辨率达到80 nm,满足设计指标要求。证明了该优化设计方法是可行的,所得系统尺寸小、性能高。     

具有尾翼的复杂导弹模型超宽带散射特性分析

为了满足对复杂导弹测量和检测的需要,该文建立了具有尾翼的复杂导弹模型,研究在极窄脉冲照射条件下该导弹目标散射特性。利用时域有限差分(Finite-Difference Time Domain, FDTD)法计算该导弹模型的瞬时散射回波,分析远场电磁波不同入射条件下导弹散射回波特性及近场不同转角条件下导弹瞬时散射回波特性。通过对该导弹瞬时散射回波特性分析,得出了目标散射中心的成因及散射波形特点,在雷达应用领域具有一定的理论参考价值。     

基于非准直外腔的单频激光高阶回馈效应研究

对基于非准直外腔的单频激光高阶回馈现象及产生机理进行了研究,获得了调制幅度不均匀的高分辨率多重高阶回馈条纹,分析了多重高阶回馈条纹的特点及产生机制。提出采用基于光路阻挡的实验方法,在回馈镜反射率大于90%的强回馈中,发现了单重高阶回馈效应,获得了调制幅度均匀、无大包络的高分辨率单重高阶回馈条纹,其分辨率达到/10,而且还有进一步提高的潜力。单重高阶回馈条纹不但具有多重高阶回馈时高分辨率的优点,还具有传统弱回馈时调制幅度均匀、类正弦等特性,对进一步研制高精度回馈测量系统具有重要意义。     

巧借二氧化碳气体扩散探究微粒运动性

借助于二氧化碳气体的扩散性,选用澄清石灰水、石蕊试纸、燃着的木条、二氧化碳(或氧气)数字传感器等检验物品,设计出多个"探究微粒运动性"的实验,并达到了现象明显、绿色环保、新颖有趣、真实可信等效果。     

紫外单光子成像系统增益特性研究

介绍了基于微通道板和楔条形阳极的紫外单光子成像系统的组成和工作原理.利用该系统分别研究了两块和三块微通道板在不同电压下的暗计数特性.实验和拟合结果表明微通道板的暗计数脉冲幅度呈负指数型分布,暗计数率随电压升高而增大.通过测试不同电压下的脉冲幅度分布曲线,发现微通道板增益在较高电压下更加均匀.研究了两块微通道板情况下,微通道板电压和间距对系统分辨率的影响.结果表明,系统分辨率随微通道板电压增加而提高;另外,适当增加微通道板间距也可以提高系统分辨率. 关键词： 单光子计数成像 微通道板 楔条形阳极 分辨率     

Design of a new compact THz source based on Smith-Purcell radiation

In recent years, people are dedicated to the research work of finding compact THz sources with high emission power. Smith-Purcell radiation is qualified for the possibility of coherent enhancement due to the effect of FEL mechanism. The compact experiment device is expected to produce hundreds mW level THz ray. The electron beam with good quality is provided under the optimized design of the electron gun. Besides, the grating is designed as an oscillator without any external feedbacks. While the beam passes through the grating surface, the beam bunching will be strong and the second harmonics enhancement will be evident, as is seen from the simulation results.     

晶粒棱长、尺寸与拓扑学特征之间关系的Monte Carlo仿真研究

采用Potts模型Monte Carlo方法研究了晶粒棱长、尺寸与拓扑学特征之间的统计关系.结果表明,晶粒棱长与晶粒面数之间呈线性统计关系,并且平均N面体晶粒模型和Poisson-Voronoi组织均支持该结论.不同时刻的晶粒长大仿真数据表明,在准稳态晶粒长大阶段晶粒棱长的分布具有自相似性.个体晶粒的平均棱长随晶粒面数（或晶粒尺寸）的增加而逐渐增大,这说明一些理论模型中采用的“不同面数的晶粒平均棱长均相等”的假设具有局限性.仿真数据和纯铁实验数据均表明,晶粒尺寸与晶粒面数之间的统计关系表现为一条单调递增的凸曲线. 关键词： 晶粒棱长 晶粒尺寸 拓扑学 Monte Carlo仿真     

Stimulated Emission from a TiO2 Particle-Dispersed Dye Polymer Plane Waveguide

We report the stimulated emission from a dye doped polymer plane waveguide with TiO2 particles. This waveguide consists of a poly （methylmethacrylate） （PMMA） film containing laser dye DCM as a gain medium. The emission spectrum of the film pumped by the Nd：YAG laser is different from the amplified spontaneous emission of the dye-doped film without particles. It is shown that when the excitation intensity reaches the threshold 9.6 μJ, the broad band emission spectrum narrows into multiple separate peaks with central wavelength of 608 nm. The linewidth of the sharp peak is 0.5 nm. According to our analyses, this phenomenon is due to the multiscattering of the disordered TiO2 particles inside the gain polymer film.     

Hydrothermal Synthesis and Vacuum Ultraviolet-Excited Luminescence Properties of Novel Dy^3＋-doped GdPO4 White Light Phosphors

Novel Dy^3＋-doped GdPO4 white light phosphors with a monoclinic system are successfully synthesized by the hydrothermal method at 240℃. The strong absorption at around 147nm in the excitation spectrum is assigned to the host absorption. It is suggested that the vacuum ultraviolet excited energy is transferred from the host to the Dy^3＋ ions. The f - d transition of the Dy^3＋ ion is observed to be located at 182nm, which is consistent with the calculated value using Dorenbos＇s expression. Under 147nm excitation, Gd0.92PO4：0.08Dy^3＋ phosphor exhibits two emission bands located at 572 nm （yellow） and 478 nm （blue）, which correspond to the hypersensitive transitions ^4 F9/2-^6 H13/2 and ^4 F9/2-^6 H15/2. The two emission bands lead to the white light. Because of the strong absorption at about 147nm, Gd0.92PO4：0.08Dy^3＋ under vacuum ultraviolet excitation is an effective white light phosphor, and has promising applications to mercury-free lamps.     

DERIVATIVES OF EIGENPAIRS OF SYMMETRIC QUADRATIC EIGENVALUE PROBLEM

Derivatives of eigenvalues and eigenvectors with respect to parameters in symmetric quadratic eigenvalue problem are studied. The first and second order derivatives of eigenpairs are given. The derivatives are calculated in terms of the eigenvalues and eigenvectors of the quadratic eigenvalue problem, and the use of state space representation is avoided, hence the cost of computation is greatly reduced. The efficiency of the presented method is demonstrated by considering a spring-mass-damper system.