仅用参考物功率谱取阈的二元联合变换相关器

提出一种用特征物功率谱取阈值的新型二元联合变换相关器。与传统的联合变换相关器相比较,它有高光能效率、高鉴别率和输入空间宽带的优点;与现行的二元联合变换相关器相比较,它有鉴别率高和不需靶物功率谱测量的特点,因而是一种简便和高性能的相关器。     

超轻小型投影式头盔显示系统折-衍混合物镜设计

在一个7片物镜的基础上,设计出一个折射和一个5片镜的折衍混合投影物镜系统,并给出了详细设计过程及性能评价。系统针对33.02 mm(1.3英寸)微显示器设计,视场为56°,出瞳直径为10 mm,出瞳距离为25mm。设计的折射系统和折衍混合系统的镜头直径分别为28 mm和22.4 mm,重量分别只有33 g和11.9 g,且最大畸变分别为3.2%和0.17%,分辨率满足SXGA显示模式。两系统均满足投影式头盔显示器在交互环境、医学可视化训练和数字化个兵等领域的使用要求。     

泽尼克各项像差对人眼光学质量的影响

基于两个人眼光学质量客观评价标准同心相对瞳孔平面(PFWc)和区域调制传递函数(Marea MTF),研究和分析了波前像差均方根值WRMS处于0.05~1.00μm较大范围内泽尼克各项像差对人眼光学质量的影响。分析结果表明,泽尼克各项在WRMS一定时,瞳孔中心区域的光学质量差距明显,离焦(C4)和球差(C12)项的MPFWc值最小,而五叶草(C15、C20)项的MPFWc值最大。五叶草项在WRMS值处于0.05~1.00μm的范围内,其Marea MTF值均大于0.94,表明该像差项对光学质量的影响可以忽略。MPFWc值和Marea MTF值随着WRMS值的增大而减小,但不是简单的线性关系,随着WRMS值的增大,它们的变化趋于平缓。各项泽尼克像差对人眼光学质量的影响存在较大差别,对人眼光学质量的影响从大到小依次为:球差、离焦、散光、彗差、三叶草、四叶草、五叶草等。     

有效介质近似在Cu-MgF2复合纳米颗粒薄膜光学性质中的适用性研究

采用射频磁控共溅射技术制备了Cu体积分数分别为15%和30%的Cu-MgF2复合纳米颗粒薄膜。透射电镜形貌图像表明,薄膜由不同形状的Cu晶态纳米微粒镶嵌于主要为非晶态的MgF2陶瓷基体中构成。用椭偏光谱技术计算得到Cu-MgF2复合薄膜在270~830 nm波段的光学常数谱。用考虑颗粒形状效应的有效介质近似计算得到Cu-MgF2复合薄膜在相同波段的光学常数谱。把两样品的透射电镜形貌图像与光学常数理论谱、实验谱相结合,分析讨论了Cu-MgF2复合薄膜的光学特性。结果表明:去极化因子取值0.33的麦克斯韦噶尼特(Maxwell-Garnett)模型可以较好地解释Cu体积分数为15%的Cu-MgF2复合薄膜的光学性质,而去极化因子取值0.6的布鲁格曼(Bruggeman)模型可以较好地解释Cu体积分数为30%的Cu-MgF2复合薄膜的光学性质。     

NO与NO2在ZnO表面吸附的密度泛函理论研究

采用 DMol ³ 模块中广义梯度密度泛函理论(GGA)的Perdew-Burke-Ernzerh(PBE)方法研究含能材料分解气体产物NO, NO₂在ZnO(10 \bar{1} 0)表面的吸附和NO₂解离生成NO和O的过程. 结果表明, 优化后的吸附构型显示Zn顶位为稳定吸附位点, NO₂的吸附能大于NO. 态密度图分析结合差分电荷密度图表明, NO的N原子与表面Zn有相互作用, 电荷从NO转移到表面; NO₂的N_2p, O_2p轨道与表面Zn_3d轨道发生杂化, NO₂附近积累大量负电荷. 过渡态搜索显示NO₂的解离需跨过较高能垒, 不易进行.     

Dependence of electrical field and photoresponse on multiplication region thickness for GaN APDs

A visible-blind ultraviolet GaN back-illuminated avalanche photodiode with separate absorption and multiplication regions (SAM APDs) are simulated based on drift-diffusion equation. The current–voltage characteristics of the device have been numerically obtained. The result is in good agreement with the experimental data. It was found that the thickness of the multiplication layer is important to improve the electrical field profiles and spectral response characteristics. A peak responsivity of 106.5 mA/W is achieved at 364 nm corresponding to the cutoff wavelength of GaN.     

Light-emitting conjugated polymers with microporous network architecture: interweaving scaffold promotes electronic conjugation, facilitates exciton migration, and improves luminescence

Herein we report a strategy for the design of highly luminescent conjugated polymers by restricting rotation of the polymer building blocks through a microporous network architecture. We demonstrate this concept using tetraphenylethene (TPE) as a building block to construct a light-emitting conjugated microporous polymer. The interlocked network successfully restricted the rotation of the phenyl units, which are the major cause of fluorescence deactivation in TPE, thus providing intrinsic luminescence activity for the polymers. We show positive "CMP effects" that the network promotes π-conjugation, facilitates exciton migration, and improves luminescence activity. Although the monomer and linear polymer analogue in solvents are nonemissive, the network polymers are highly luminescent in various solvents and the solid state. Because emission losses due to rotation are ubiquitous among small chromophores, this strategy can be generalized for the de novo design of light-emitting materials by integrating the chromophores into an interlocked network architecture.     

Ce∶KNSBN光折变类光纤简并四波混频特性研究

研究了Ce∶KNSBN光折变类光纤在泵浦光和信号光夹角分别为小角度和大角度两种情况下简并四波混频的基本特性 .当夹角较大时 ,在光折变类光纤内部形成了两个四波混频作用区域 ,获得了比小角度情况提高 4倍的大相位共轭反射率 .给出了Ce∶KNSBN光折变类光纤中 ,在入射夹角分别为小角度和大角度两种情况下 ,相位共轭光反射率分别随信号光光强、两束泵浦光光强比变化的实验结果 ,并用理论公式进行了拟合 ,理论分析和实验结果相符 .还研究了Ce∶KNSBN光折变类光纤四波混频光栅模式和相位共轭光时间响应特性 .光折变类光纤的相位共轭响应时间较快 ,可为秒量级 .