光学镜头调制传递函数的测试

为了定量、客观、全面地评价光学镜头的像质,介绍了光学镜头调制传递函数的测试。先简要叙述了测试的原理,并给出计算公式;然后介绍了测试步骤,其中包括固定、穿轴、测试中心视场和测试轴外视场;最后介绍了测试时的注意事项,包括对测试工装的要求、对测试平面的要求和正、负轴外视场测试值相差较大时的处理办法。     

Fundamental Optical Absorption Edge of Sputter-Deposited Zirconia and Yttria

Zirconia and yttria films were sputter deposited onto unheated fused silica substrates using a metal target and rare gas-oxygen discharges. Double-beam spectrophotometry was used to measure the transmission and reflection as a function of incident photon energy, E , from which the absorption coefficient, α( E ), was calculated. An indirect interband transition at E _i= 4.70 eV and two direct interband transitions at E _g1= 5.17 eV and E _g2= 5.93 eV occur in monoclinic zirconia. Two direct interband transitions at E _g1= 5.07 eV and E _g2= 5.73 eV occur in cubic yttria. The absorption edge structure is modified when unusual phases, such as tetragonal zirconia, and zirconia and yttria with no longrange crystallographic order, are present.     

基于光纤像面全息的金属构件微位移测量

针对激光全息技术能处理常规方法难以解决的问题以及光纤具有环境适应性的特点,设计了一种基于光纤像面全息干涉计量对金属材料构件微小位移测量的方法.通过对不同芯径传像光纤束情况下的成像结果分析,得出了与材料力学相符合的结论.实验结果表明,提出的方案适用于对金属材料特性的高精度测量,可以解决阻碍激光全息技术推广应用和发展的环境要求.     

观测几何对目标探测性能影响的仿真分析

在光电武器作战探测目标性能问题的研究中,不同大气/气溶胶模式、不同观测几何条件下的光电武器作战效能差异显著.针对上述问题,通过分析大气传输和观测几何对视在对比度的影响,建立了视在对比度传递模型,结合TIP准则提出了观测几何对目标探测性能的影响模型.利用Modtran软件离线计算的基础数据,提出了探测性能模型快速仿真计算方法,实现了典型地区、全天时、不同观测几何和观测距离条件下的成像系统探测性能的快速仿真计算.采用快速仿真计算方法,选取典型参数,计算并分析了不同大气/气溶胶模式、观测几何等因素对视在对比度、探测概率和探测距离等指标的影响.结果表明:观测几何对目标探测性能影响显著,50％探测概率条件下,顺光探测距离是逆光探测距离的1.38 ～1.7倍;不同大气/气溶胶模式条件下,观测几何对探测距离影响差异明显,海洋性气溶胶模式下影响较大,乡村型气溶胶模式下影响较小.文中提出了观测几何对目标探测性能的影响模型和快速仿真计算方法,为光电武器系统任务规划和作战效能评估提供了理论和技术支持.     

激光谐振腔内倾斜误差的自适应校正

我们设计制作了一种性能良好的倾斜镜,试验了两种校正系统:微机控制的试探爬山法系统和高频振动爬山法系统。实验结果表明,这两种校正系统,都可以成功地校正腔内倾斜误差。最后,比较了两种校正系统的优缺点。     

Influence of chromium on the local structure and morphology of ferric oxyhydroxides

The extended X-ray absorption fine structure (EXAFS) method and transmission electron microscopy (TEM) have been used for characterizing the local structure and morphology of ferric oxyhydroxides, α-FeOOH and γ-FeOOH, with and without chromium. These ferric oxyhydroxide powders were prepared from aqueous solutions containing iron and chromium ions. Radial structural functions for iron obtained by Fe K edge EXAFS spectra showed that the linkage of structural units formed by FeO₆ octahedra in γ-FeOOH is distorted by chromium addition, while such distortion in α-FeOOH is not clearly detected. On the other hand, Cr K edge EXAFS spectra showed that the local structure around chromium does not necessarily correspond to the local structure around of iron, which is observed by Fe K edge EXAFS spectra. This suggests that the structural units containing iron and chromium are heterogeneously distributed in these ferric oxyhydroxides. The local structural information was discussed coupled with morphological features of these ferric oxyhydroxides observed by TEM.     

基于改进Rank变换和分段MER的镜片疵病检测算法

为了解决目前光学镜片表面疵病宽度测量主要依赖人工检测而导致弯曲划痕宽度检测精度较低的问题,提出一种基于Rank变换和分段最小外接矩形(MER)的镜片表面划痕宽度测量方法.该方法首先通过改进的Rank变换算法比较像素灰度相对关系来提取疵病目标,然后计算其最小外接矩形,根据矩形长宽比初步判别疵病类型(划痕或麻点),最后将疵病分割为多个小区段,分别计算每段的最小外接矩形并获得其宽度,比较取最大宽度作为疵病宽度值.试验结果表明,该方法具有较高的可行性与精确性,能够有效提取出疵病和计算其特征参数,可以满足工程实际的需要.     

Harvesting light with transformation optics

Transformation optics （TO） is a new tool for controlling electromagnetic fields. In the context of metamaterial technology, it provides a direct link between a desired electromagnetic （EM） phenomenon and the material response required for its occurrence. Recently, this powerful framework has been successfully exploited to study surface plasmon assisted phenomena such as light harvesting. Here, we review the general strategy based on TO to design plasmonic devices capable of harvesting light over a broadband spectrum and achieving considerable field confinement and enhancement. The methodology starts with two-dimensional （2D） cases, such as 2D metal edges, crescent-shaped cylinders, nanowire dimers, and rough metal surfaces, and is well extended to fully-fledged three-dimensional （3D） situations. The largely analytic approach gives physical insights into the processes involved and suggests a way forward to study a wide variety of plasmonic nanostructures.     

复杂地形下自动提取多暗像元的TM影像大气纠正方法

复杂地形条件下气溶胶的空间分布变化较大,用单一的气溶胶实测参数或单一的暗像元进行大气纠正都难以获得好的效果,手动选取暗像元还受限于专业人员的经验。通过程序自动提取图像中的浓密植被像元以及位于山区阴影的植被像元作为暗像元,使得暗像元均匀分布于图像的各个区域、各个海拔,更好地模拟复杂地形下的大气状况。根据辐射传输模型,利用迭代、插值等方法获取TM1和TM3波段光学厚度,进而推算成像时刻的气溶胶波长指数及混浊度系数,从而得到各个波段的大气光学厚度以实现大气纠正。     

飞秒激光在6H-SiC表面诱导偏振依赖纳米结构特性研究

激光诱导偏振依赖纳米结构是一种有效实现纳米图案化的技术,并且一直备受研究者的青睐。利用飞秒激光微加工技术,对6H-SiC晶体表面激光诱导偏振依赖纳米结构特性进行了研究。通过改变入射激光加工偏振态和延迟时间样品表面诱导产生了直径约为150 nm的球形纳米颗粒、椭圆形纳米颗粒和空间周期约为150 nm的高空间频率表面条纹结构。实验结果表明,入射激光偏振特性会直接影响诱导产生的微结构形貌,并且优先入射的飞秒激光对最终产生的表面微结构形貌有决定性作用。初步探讨了偏振依赖纳米结构形成的物理机制,表面等离激元(surface plasmon polariton, SPP)在表面微纳米结构的产生过程中扮演着重要角色,研究结果对激光诱导表面周期结构(laser-induced periodic surface structures, LIPSS)可控制备具有重要意义。