氟化镁整流罩的高速抛光

整流罩在高速飞行中对空气进行整流 ,并同时起光学窗口的作用。热压多晶氟化镁常用作整流罩材料。但在加工中发现 ,这种材料易出现散射颗粒 ,严重影响零件的表面质量。通过高速抛光工艺的摸索 ,提高了零件的表面质量 ,缩短了抛光时间 ,提高了生产效率。     

中波红外导弹用高强纳米红外陶瓷整流罩特性研究

红外整流罩位于导弹的最前端,是红外导弹的主要部件之一。根据其工作环境的要求,红外整流罩应具有良好的光、机、热等性能。目前,中波红外导弹的红外整流罩主要采用氟化镁、蓝宝石、尖晶石、ALON和纳米复相陶瓷等材料制造。本文提出了一种高强稀土氧化物稳定的ZrO_2纳米红外透明陶瓷整流罩,通过对陶瓷材料的特性进行研究,证明了该种材料可以用于中波红外导弹。同时,采用该种材料完成了红外整流罩样件的研制,并对样件进行了导弹服役环境下的适应性试验和模拟动态抛罩试验,验证了该材料的性能。     

集群磁流变抛光参数对亚表面损伤深度的影响

建立了亚表面损伤深度与抛光参数的关系模型,探究集群磁流变抛光后单晶蓝宝石亚表面损伤深度与集群磁流变抛光参数的关系,研究了抛光参数对亚表面损伤深度的影响规律,运用正交实验验证了模型的合理性.实验中使用白光干涉仪作为测量工具,α-Al_2O_3抛光液作为抛光液,每个实验因素选择三个水平,结果表明:集群磁流变抛光中,单晶蓝宝石亚表面损伤深度与磨粒粒径和抛光压力有关,亚表面损伤深度随着抛光压力和磨粒粒径的增大而增大,抛光压力对亚表面损伤深度的影响远大于磨粒粒径.当抛光压力和磨粒粒径分别为25kg和280nm时,经过100min抛光,亚表面损伤深度最小值达到0.9nm.在集群磁流变抛光中抛光压力是影响亚表面损伤深度的主要因素,当抛光压力为25kg时,集群磁流变抛光可快速去除亚表面损伤.     

飞秒激光微加工蓝宝石晶片光纤压力传感器

提出了一种高温大量程的蓝宝石法布里-珀罗（F-P）干涉仪压力传感器。传感器由三层蓝宝石晶片直接键合而成，包括蓝宝石衬底、带通孔的蓝宝石晶片和感压蓝宝石晶片。飞秒激光用于在蓝宝石晶片的中心刻蚀通孔，并粗糙化感压蓝宝石晶片的外表面。利用蓝宝石晶片抛光面作为F-P腔的反射面，有助于降低解调出的光学腔长波动，提高压力分辨率。提出的传感器在室温、0～30 MPa的高压力范围内光学腔长随压力线性变化，压力灵敏度为0.1253μm/MPa，相对分辨率达到0.04%FS(full scale，全量程)，且能在700℃下稳定工作。     

100 GPa以上冲击压力区蓝宝石的近红外发光

采用三层夹心靶结构,利用铜箔与抛光蓝宝石之间良好的接触条件,使用辐射式高温计观测到c取向蓝宝石在130～172 GPa冲击高压下的红外辐射。实验信号显示,位于近红外波段的蓝宝石冲击辐射随着压力的增加而变强;强度对比显示,蓝宝石的近红外发射强于界面发射。基于冲击作用下滑移带的温度高于冲击平衡温度的概念,将蓝宝石体内滑移带温度作为蓝宝石发射温度代入线性吸收公式,从而将蓝宝石发光强度的增加和界面冷却引起的发光强度下降相结合;将得到的界面一蓝宝石发射强度数值模拟结果与实验结果相比较,发现二者能够重合。由实验信号的上升趋势得到三个压力下0.85μm近红外波长处蓝宝石的冲击吸收系数数值。     

蓝宝石光纤探针传感器探针研制工艺及传光测试

在分析比较传统光纤探针研制工艺特点的基础上认为其不适用于蓝宝石光纤,因此提出了基于研磨抛光系统的光纤探针制备工艺。介绍了研磨系统的组成及运作方式,阐述了光纤探针制备过程中研磨抛光与固化的主要流程。最后使用光学仿真软件Zemax进行了光纤探针传输效率的仿真测试,仿真结果表明采用940nm波段光源及"面对面"探头安置方式时光纤探针传输效率最高。可应用于蓝宝石光纤探针传感器系统的搭建。     

基于环摆式双面抛光法加工预测模型的去除均匀性研究

针对环摆式双面抛光难以建立稳定去除函数并进行加工面型预测这一问题,提出了基于磨粒运动学的环摆式双面抛光加工预测模型,并通过预测模型分析不同参数影响下元件表面去除均匀性,针对不同特征面型给出优化策略以指导加工实验。首先,根据环摆式双面抛光机理,探究了环摆式双面抛光中影响去除均匀性的主要因素,提出了元件上、下表面磨粒运动学模型,结合Preston方程给出了基于磨粒运动学的环摆式双面抛光去除均匀性预测模型。根据实际加工工况,分析了不同抛光均匀性影响因素下的磨粒轨迹分布与抛光去除非均匀性,最后通过加工实验验证环摆式双面抛光加工预测模型。实验结果表明：环摆式双面抛光加工预测模型的预测结果与实际加工结果基本吻合,其面型去除特征相同。元件上表面是元件去除非均匀性的主要来源,通过改变中心偏心距、径向摆动距离等参数能改变元件上表面的去除非均匀性,从而影响元件整体面型特征,并实现基于预测模型指导下元件表面面型的快速收敛。     

双面抛光运动的数学建模及轨迹优化

双面抛光运动过程复杂,对光学材料的加工有重要的影响,运动轨迹分布不但影响加工效率,而且影响加工工件的表面质量.通过分析双面抛光加工的运动过程,建立双面抛光中任意一点相对于上抛光盘的运动轨迹的数学模型,改变数学模型中的轨迹运动参数,观察不同参数值对抛光轨迹分布的影响,优化分析得出抛光轨迹分布最佳的运动参数值.研究结果表明...     

高功率激光晶体加工技术的研究

针对高功率激光器中使用的激光晶体关键元件,开展了晶体的先进加工技术的研究。根据LBO及YCOB晶体材料的加工特性,选取了定向切割、研磨、预抛光、磁流变抛光、合成盘抛光和机械化学抛光的总体技术路线。对不同种类晶体加工设计了不同的工艺路线,开展了相关加工工艺研究。其中LBO晶体的面形收敛工艺主要采用磁流变抛光,YCOB晶体的面形工艺主要采用合成盘抛光。通过组合加工工艺,获得了高质量的晶体加工指标,LBO晶体透射波前0.12λ(λ=632.8nm),粗糙度0.77nm;YCOB晶体面形0.11λ,粗糙度0.68nm。确定了晶体元件的整体加工技术路线,并对整个工艺流程开展了工艺实验研究,取得了较好的实验效果,实现了激光晶体的高质量加工指标。     

纳米级面形精度光学平面镜加工

为实现纳米级面形精度光学平面镜的高效精密抛光,提出了一种由传统环带抛光技术和先进离子束抛光技术相结合的组合式加工方法。介绍了环带抛光技术和离子束抛光技术的原理,通过实验研究了离子束抛光的材料去除函数,并采用这种组合抛光方法对口径为150 mm的平面镜进行抛光,抛光后平面镜的面形误差和表面粗糙度分别达到1.217 nm RMS和0.506 nm RMS。实验结果表明,这种组合抛光技术适合纳米级面形精度光学平面镜的加工。     

Observation of optical non-reciprocity in a single layer of transparent linear chiral media with asymmetric boundaries

We report the observation of optical non-reciprocity in a material system that is very close to natural structures, such as insect skin: a single layer of linear transparent material in its ground state. The process is shown to be determined by two key parameters: the chirality of the material and its asymmetric boundary conditions. Our qualitative and preliminary quantitative analyses are in very good agreement with experimental results.     

碱性品红敏化的光致聚合物在441nm短波长的全息存储特性研究

制备了一种以碱性品红为光敏剂的新型全息存储材料,且使用波长为441nm的He—Cd激光器成功研究了材料的全息特性。研究表明,该材料在短波长处仍具有较高的衍射效率、曝光灵敏度和较大的折射率调制度,衍射效率近60％,灵敏度为2．93×101c群／mJ,折射率调制度为8．85×10．。。在存储介质膜中存储了全息图像,再现图像较为清晰,对比度与保真度较为理想,说明该材料具有较好的全息存储性能,适合作为高密度全息存储介质。     

Experimental and theoretical study of multiscale damage-failure transition in very high cycle fatigue

Multiscale mechanisms of failure of metals (Armco iron, titanium, aluminum) are studied for high cycle and very high cycle fatigue. By correlating with the results of structural studies, a theoretical approach is developed to describe fatigue crack kinetics in damaged material under high cycle and very high cycle fatigue loading conditions. Stages of crack nucleation and propagation are analyzed using the profilometry data from the fracture surface. The scale invariance of fracture surface roughness is established, which allows an explanation of the self-similar nature of fatigue crack kinetics under high cycle and very high cycle fatigue. Variation of elastic-plastic properties of Armco iron under very high cycle fatigue is studied using an acoustic resonance method. It is found that the material density decreases during fatigue damage accumulation, with the minimum of the material density in the bulk of the specimen.     

A very compact Mach-Zehnder interferometer with left-handed material

A very compact Mach-Zehnder interferometer (MZI) composed of two parallel straight waveguides with left-handed material (LHM) layers is proposed. The operating principle and characteristics of the MZI with electro-optic material (EOM) core are analyzed by using the supermode theory and coupled mode theory. The result shows that regardless of material loss, a very compact MZI of only 0.87 mm × 0.022 mm can be achieved by utilizing EOM with ultrahigh electro-optic coefficient, which means a new way to fulfill a very compact electro-optic modulator or optical switch. The absorption effect of the proposed MZI is also analyzed by perturbation method which is generated by lossy LHM layers.     

Generalized Locking Profile for Angular Particles - Locked Particle Theory

Locked particles are defined as those comminuted or particles which contain both gangue and target material. By considering the shape of the comminuted particles and assuming their random distribution in the ore body prior to comminution, it is possible to derive locking profiles which give the frequency of occurrence of particles which have a given fraction of their volume occupied by target material. For most particle shapes (spheres, angular particles, angular plates and rods) the locking profile is a deep U-shaped curve. This suggests that few particles by number contain about 50% target material while a far greater number contain either very little or very much target material. Such a conclusion is important in planning separation processes for locked particles in the mineral industry.     

光子晶体对nc-Ge/Si岛发光增强的模拟

在Si基集成光电子学的发展中,高效的Si基光源是人们不懈追求的目标。但是Si材料的间接带隙特性导致其发光效率低,更谈不上受激发射。于是人们探索了多种Si基材料体系来提高Si材料的发光效率,并在不同程度上取得了重要的进展。在众多的Si基发光材料体系中,Ge/Si量子点材料,不仅生长工艺与标准的CMOS工艺有很好的兼容性,而且发光波长能够覆盖重要的光通信波段即1.3~1.55μm,因此成为实现Si基发光器件的重要途径之一。但是目前这种材料的发光效率仍很低,所以提高其发光效率自然成为人们关注的焦点。如果将光子晶体引入到nc-Ge/Si材料中,它不仅可以改变材料本身的自发发射特性,而且可以改变发射的光子的提取效率,从而使材料的发光效率得到增强。提出了在Ge/Si量子点材料中引入光子晶体结构来提高其发光效率,包括光子晶体点缺陷腔结构和带边模式工作的完整光子晶体结构,并从理论上分析了发光效率提高的原理。针对发光波长在1.5μm附近的材料结构,模拟出了相应的光子晶体的结构参数。从模拟结果可以看出,对于缺陷腔的光子晶体结构,采用单点缺陷微腔很好地实现了单模运作,但是微腔内有源材料的体积很小,因此得到的发光效率很低。而采用耦合缺陷腔的结构和H₂腔都增加了腔内有源区的体积。但是耦合腔与H₂腔相比,谐振腔模减少,主谐振模式的峰值强度增加,更容易实现单模发光。因而更适用于提高nc-Ge/Si的发光效率。而带边模式工作的光子晶体结构,尺寸较大,不需引入缺陷,工艺上更容易实现。     

Simultaneous determination of the X-ray refractive index and the attenuation length from a single digitally registered radiograph of rectangular prisms

Prisms deflect and disperse X-rays due to refraction very similar to visible light. As X-rays are always attenuated while traversing material, the intensity distribution in the transmitted beam carries information about the prism transmission function. This study will show that sufficient information is contained in a single digitally registered radiograph from a rectangular prism, for deriving both the refractive index of the material and its attenuation length. The measured data can be prepared such that neither intensity fluctuations nor false light content in the incident beam will introduce systematic errors into the result. The strategy is thus very adapted, when single shot pictures are taken at X-ray sources with limited shot reproducibility. This technique is favourably be used at very grazing angles of incidence of the order of the critical angle for the prism material, when the beam deflection becomes significant. In such a geometry dimensional parameters, like sample thickness, do not affect the data analysis, which is particularly insensitive to even significant errors in the tip angle.     

The applications of nuclear track detectors in transuranic contamination problems

Nuclear Track Methodology (NTM) is very well known for its possibilities in applications in a wide variety of fields. The appearance of the polycarbonate as alpha radiation detector material, established a very confident monitoring surface alpha contamination, soil and water alpha activity. The purpose of the study is to investigate the utility of the CR-39 (Allyl Diglycol Carbonate) in fast semi-quantitative transuranic contaminant evaluation, including the distribution in underground contaminated soils, hot spots and transuranic material accumulations.     

Hugoniot线上的一个经验常数——来自多孔材料Hugoniot数据的对比研究

 对不同初始密度样品冲击压缩Hugoniot数据的系统分析显示，对每种固体物质而言存在一个表征材料特性的沿其Hugoniot线不随冲击压力而变的经验常数β。β的数值随材料而异。对金属元素而言，该经验特性常数β与初始密实密度ρ₀之间遵循同一个幂指数关系。利用该常数β，可很方便地对不同初始密度的Hugoniot数据进行换算，并可以很方便地获得Grüneisen参数。还对β值为常数的适用范围作了讨论。     

Na+离子掺杂Gd2O3 ∶ Sm3+纳米晶的发光增强

采用柠檬酸作燃烧剂,在柠檬酸-硝酸盐体系下制备了Gd₂O₃ ∶ Sm³⁺和Gd₂O₃ ∶ Sm³⁺,Na⁺纳米晶。用X射线衍射仪、透射电子显微镜、荧光光谱仪等对样品的结构、形貌和光致发光性能进行了分析。结果表明:所得纳米样品为纯立方相,晶粒尺寸约为30 nm。在室温下,用275 nm激发光激发各样品时,可观测到Sm³⁺离子 的较强发光,其主发射峰位分别位于561.5,603.5,651.5 nm,分别对应着Sm³⁺离子的⁴G_5/2→⁶H_5/2 , ⁴G_5/2→ ⁶H_7/2 和⁴G_5/2 →⁶H_9/2的电子跃迁, 其中以⁴G_5/2→⁶H_7/2 跃迁的光谱强度最强。实验表明:Na⁺离子的掺入使得Sm³⁺离子的光发射强度显著增强。对引起样品荧光强度变化的原因进行了分析。