基于氧气A吸收带的baseline拟合距离反演算法

目标红外被动测距的实现同气体及其波段的选取密切相关。氧气A吸收带具有独特的谱线结构,对于火箭羽流或者高温辐射体的距离探测,氧气A吸收带是最佳的距离反演通道。利用该特点,详细研究了逐线积分算法(LBLRTM),并设计了氧气A带吸收系数及标准光谱计算软件;利用A吸收带吸收光谱带外数据,采用多项式拟合方法,实现基线(baseline)拟合,进而得到带平均透过率;在不同的距离条件下,将两种带平均透过率进行对比,误差在1.9%左右,拟合精度较高,该方法为后续距离的精确反演提供了理论依据。     

Quantitative evaluation of equatorial small-angle X-ray scattering for cylindrical fibers

Elongated microvoids, internal fibrillar structure, and edge scattering from both surface refraction cause an equatorial streak in small angle X-ray scattering. A model for analyzing the edge scattering of fibers is proposed. Simulation results indicate that the intensity of edge scattering from surface refraction of a cylindrical fiber is strong and makes an important contribution to the equatorial streak. Two factors influence edge scattering intensity. One is the sample-to-detector distance (D); edge scattering intensity increases with increasing D. The equatorial streak becomes weak when D is shortened. The other factor is the refraction index. Edge scattering intensity increases as the real component of the refraction index decreases. In experiment, weak or even no equatorial streaks were found for samples measured in a roughly index-matching fluid. Edge scattering can be eliminated or weakened, and it can be calculated by comparing the intensities of a cylindrical fiber when it is measured in air and in index-matching fluid. The simulation data are basically in agreement with the experimental data.     

并五苯同质异相体中分子间势能与能带计算

采用Born-Mayer-Haggins对势模型，分析了并五苯分子间势能及其相互作用. 用紧束缚模型计算了两种并五苯同质异相体结构的能带宽度. 计算带宽随温度升高减小8%—14%. 关键词： 并五苯 同质异相体 分子间势能 能带计算     

一种基于强边缘块的时域多分辨率图像分割算法

针对序列图像的变化检测,提出了一种基于强边缘块的时域多分辨率图像分割算法.首先在具有明显边缘特征的图像序列中,提取图像强边缘块的直方图,然后,利用时域多分辨算法,比较不同帧之间的图像差异.这种方法不但能够检测出图像的变化,而且能够确定图像变化的类型.在阈值的选取过程中,采用了自适应阈值方法,实验证明这种方法取得了较好的效果.     

用一维光子带隙结构增强硫化镉双光子吸收研究

用真空镀膜方法制备了含有单个CdS缺陷层的具有不同周期和结构参量的TiO2／SiO2一维光子晶体。用抽运一探测技术研究了CdS缺陷层的双光子吸收（TPA）现象。实验结果表明：一维光子晶体中CdS缺陷层的双光子吸收显著增强。不同周期和结构参量的一维光子晶体中CdS缺陷层的双光子吸收系数不同。双光子吸收的增强来源于由光局域化导致的缺陷层的电场强度的增加。缺陷层电场强度与一维光子晶体的结构有关,如周期,光子带隙的位置与宽度及缺陷模式等因素都会影响缺陷层电场强度。采用四分之一波长的高低折射率介质层和与入射波长匹配的缺陷模可以得到最大的缺陷层电场强度。     

Cr4+掺杂Li1.14Zn1.43SiO4透明微晶玻璃近红外宽带光谱特性

采用高温熔融法和热处理制备了Cr⁴⁺掺杂Li_1.14Zn_1.43SiO₄微晶玻璃, 探讨了不同热处理温度下样品的物相、微观形貌及发光性能. 结果表明: 580℃热处理2h得到的微晶玻璃, Li_1.14Zn_1.43SiO₄微晶的粒径约为5nm, 在808nm的二极管激发下, 可观察到中心波长位于1226nm, 半高宽为230nm的近红外宽带发射峰, 荧光寿命约为200.73±1.71μs. 随着热处理温度的升高, Cr⁴⁺离子所处的晶体场环境发生了变化, 且可以观察到样品吸收光谱发生微弱的蓝移, 而荧光光谱发生少量的红移, 分析了晶体场环境变化对样品发光性能的影响. 关键词： 铬离子 微晶玻璃 超宽带发光 晶体场     

Comparison of entanglement trapping among different photonic band gap models

We investigate the roles of different qubit-environment decoherence models on the entanglement trapping of two qubits. By considering three environmental models （the single photonic band gap model, the common photonic band gap model, and the two independent photonic band gaps model）, we note that the final values of entanglement trapping are determined by these different models. We also give the conditions of obtaining the larger entanglement trapping by comparing two-qubit entanglement dynamics in different decoherence models. Moreover, the comparison of entanglement trapping between two Bell-like states in the same decoherence model are also carried out.     

中波红外3 μm～5 μm宽带通滤光片的研制

 中波红外宽带通滤光膜通常膜系层数多,膜层总厚度非常大（厚度达到10 μm左右）,膜层的镀制工艺难度较大。通过分析红外带通滤光片几种设计方法的特点,并结合实际镀制工艺技术,采用了长波通与短波通及非规整薄膜设计技术相结合的方法,设计了以锗材料为基底的中波3 μm～５ μm宽带通滤光膜。该设计大幅度降低了膜层的总厚度（约为8.65 μm）,缩短了膜层的镀制周期,提高了膜层的牢固度;在膜层的镀制工艺过程中,通过改变薄膜材料的蒸发速率、修正蒸发硫化锌材料时电子枪的扫描方式、调整蒸发材料在坩埚中的装载方法,使膜层获得了优异的光谱性能,其通带平均透过率大于96%,截止区域的平均透过率小于1%。     

绿色植被红边特征的研究

通过系统分析绿色植被在紫外可见波段光谱的产生机理,得出绿峰和红边是由叶绿素产生的。从叶绿素的结构上看,它属于卟啉类化合物,为了进一步探究红边产生的机理,合成了四苯基卟啉、四(4-甲氧基苯基)卟啉、四(4-磺酸钠苯基)卟啉、四吡啶基卟啉、四甲基卟啉、四(4-甲氧基苯基)卟啉合锌和四(4-甲氧基苯基)卟啉合铜,并采用紫外可见光谱、红外及核磁进行表征。通过对其紫外可见光谱的系统分析,提出“红边”不仅限于叶绿素,而是卟啉类化合物特有的光谱特征,红边是由卟啉环a_2u(π)-e_g(π*) 跃迁产生的Q带所致。其位置不仅与卟啉的浓度相关,与卟啉化合物外侧取代基类型也有关系,金属卟啉对红边的位置影响较大。     

Tunable properties of light propagation in photonic liquid crystal fibers

Tunable properties of light propagation in photonic crystal fibers filled with liquid crystals, called photonic liquid crystal fibers (PLCFs) are presented. The propagation properties of PLCFs strongly depend on contrast between refractive indices of the solid core (pure silica glass) and liquid crystals (LCs) filing the holes of the fiber. Due to relatively strong thermo-optical effect, we can change the refractive index of the LC by changing its temperature. Numerical analysis of light propagation in PLCF, based on two simulation methods, such as finite difference (FD) and multipole method (MM) is presented. The numerical results obtained are in good agreement with our earlier experimental results presented elsewhere [1].