宽视场大相对孔径星敏感器光学系统设计

介绍了一种用于卫星姿态控制的星敏感器光学系统,该光学系统焦距为51 mm,相对孔径为1/1.1,视场角为21°×21°（圆视场2ω＝30°）,光谱范围为0.5～0.85 μm,采用了复杂化双高斯结构.与普通成像系统不同的是,该系统要求对不同光谱的恒星所采集到的点像能量中心是一致的,且星像点像的弥散圆须控制在一定的范围内.具有倍率色差小、轴上和轴外能量分布比较一致的特点.     

ZnS∶Zn,Pb蓝粉在低压阴极射线激发下的应用

通过对ZnS∶Zn,Pb蓝色荧光粉进行表面包覆SiO2以改善其稳定性;In2O3材料的适量混合,提高了荧光粉的导电性,降低了它的起辉电压。采用沉淀法制备荧光屏,考察了阳极电压和阳极电流对亮度以及衰减过程的影响,实验结果表明ZnS∶Zn,Pb的性能优于ZnS∶Ag,Cl和ZnS∶Zn,可适用于FED等低压显示器。     

Mössbauer studies on ultraporous Fe-Oxide/SiO2 aerogel

Magnetic aerogels with very low volume density of ～0.2 g/cm³ were prepared by sol-gel method and supercritical drying. The resulting materials were monolithic and displayed high surface area. By X-ray diffraction and Mössbauer spectroscopy the crystalline phase formed inside the mesopores of the SiO₂ matrix was identified as a spinel iron oxide. Comparison of the magnetic measurements with Mössbauer spectra at various temperatures contributed to the elucidation of the magnetic state of this nanocomposite system with restricted magnetic interactions, in particular its transition to a superparamagnetic state.     

顺磁性La2/3Sr1/3MnO3层对Bi0.8Ba0.2FeO3薄膜多铁性能的影响

界面效应在提升异质结构材料的多铁性能方面有着重要的作用. 本文采用脉冲激光沉积技术在SrTiO₃(STO)基片上制备了Bi_0.8Ba_0.2FeO₃(BBFO)/La_2/3Sr_1/3MnO₃(LSMO)异质结. X-射线衍射图谱表明异质结呈现单相外延生长, 利用高分辨透射电镜进一步证实了BBFO为四方相结构. X-射线光电子能谱证实异质结中只存在Fe³⁺ 离子, 没有产生价态的变化, 揭示了异质结铁电和铁磁性的增强与BBFO/LSMO的界面有关. 同时, 测试了磁电阻(MR)和磁介电(MD), 当磁场强度为0.8 T, 温度为70 K时, MR约为-42.2%, MD约为21.2%. 并且发现在180 K时出现磁相的转变. 实验结果揭示出异质界面效应在提升材料的多铁性和磁电耦合效应方面具有超常的优点, 是加快多铁材料实际应用的有效途径.     

同步辐射X射线成像光束线劳厄双晶单色器设计

上海光源X射线成像光束线采用多极扭摆器(wiggler)作为辐射光源, 提出一种劳厄双弯晶单色器的设计方案. 计算结果显示, 可获得固定出口的平行单色光束, 能量调谐范围覆盖19—120keV, 在33keV时, 输出光子通量及通量密度分别为1.9×10¹³phs/s和3.8×10¹⁰phs/s/mm². 分析了劳厄晶体的聚焦及单色化性能, 计算了输出光子通量及单色器的热负载情况. 与传统的双平晶方案相比, 本设计在获得高通量和解决热负载等方面有明显的优越性, 并能有效控制热形变.     

含有周期球腔的黏弹性覆盖层消声性能分析

利用散射矩阵法分析了单个球状空腔在黏弹性橡胶中的Mie散射特性以及振动模式.以此为基础，利用多重散射法分析了不同背衬条件下，含有单层周期球状空腔的橡胶覆盖层(厚度为8mm)的消声性能.结果表明，单个球腔的径向共振对覆盖层的低频消声性能有重要贡献，覆盖薄层在共振区具有良好的消声性能.最后，设计了双层消声覆盖层(厚度为20mm)，有效拓展了消声带宽. 关键词： Mie散射 多重散射法 消声材料 声子晶体     

Langmuir-Blodgett self-assembly and electrochemical catalytic property of FePt magnetic nano-monolayer

Dispersed-well FePt nanoparticles with particle size ~5 nm have been prepared by hydrazine hydrate reduction of H₂PtCl₆·6H₂O and FeCl₂·4H₂O in ethanol–water system. By employing as-synthesized FePt nanoparticles, the monolayer can be formed by LB Technique. The structural, magnetic properties and electrochemical properties of FePt monolayer were respectively studied by XRD, TEM, VSM and CHI 820 electrochemical workstation. The as-synthesized particle has a chemically disordered fcc structure and can be transformed into chemically ordered fct structure after annealing treatment above 400°C. The coercivity of ordered fct FePt phase can be up to 2515Oe. CVs of 0.5 M H₂SO₄/0.5M CH₃OH on GCE modified with FePt nanoparticles monolayer films illustrate that the as-synthesized FePt is a kind of active electrochemical catalyst.     

Spectral tuning of InGaAs/GaAs quantum dot infrared photodetectors with bandpass guided‐mode resonance filters

Quantum dot infrared photodetectors can be coupled with micro‐structured filters to create narrowband sensors. Guided‐mode resonance filters based on a high‐index dielectric slab can exhibit bandpass characteristics that are suitable for monolithic integration with focal‐plane arrays. Here, patterned Ge filters were integrated with InGaAs/GaAs quantum dot detectors to linearly tune their 77 K photoresponse peaks from 5.6 µm to 6.2 µm. The dark current was not influenced by these filters but the ability to narrow the photoresponse linewidth was limited by substrate scattering, which is often encountered with front‐side illumination architectures. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

New side-pump scheme for large mode area fiber lasers by wrapping polished fibers conjugate caustic removed

With the purpose of uniform gain coefficient along the axial direction in the core of gain guided and index anti-guided fiber, a new kind of side-pump scheme by wrapping particularly treated fibers around the central GGIAG fiber is reported in this paper. According to leakage mode analysis on wrapped fiber and numerical simulation on this pumping structure having ytterbium doped central fiber and conventional wrapped side fiber, we find this kind of pump scheme can improve the uniformity of gain coefficient along the fiber direction, and also, it can support multi channels of pumping sources by adding more side fibers to improve the total effective incident pumping power.     

制备多模聚硅氧烷光波导关键技术的改进

本文利用浇铸法,使用M&N胶和OE6450两种聚硅氧烷制备光波导.通过改进制备光波导的多个关键技术, 解决了波导制备过程中的气泡问题、脱模问题、芯层不固化问题、芯层和覆盖层产生化学反应等难题,提出了 比较完备和科学的聚硅氧烷波导制备工艺流程,从而使得波导的制备成品率从原来低于40%提高到高于80%, 波导的最大长度从原来的21 cm增加到22.5 cm,波导的损耗(截断法测量结果)从最初的0.3dB/cm(850 nm)降低到了 0.21dB/cm(850nm).本文在波导制备技术方面具有重要的实际意义和价值.