平面电磁波理想金属表面散射场分布及粗糙度参数关系的理论分析

在散射表面的均方根起伏小于入射电磁波长条件下,借用标量理论之正弦光栅衍射场分布结果,分析了不同粗糙度参量条件下,矢量微扰理论二级以上微扰项带来的偏差;并定性分析了由散射场微分角分布的测量,计算随机分布散射表面粗糙度参数的可信度。     

散射法表面粗糙度测量

介绍了标量和矢量两种散射理论，并用软X射线反射率对超光滑表面进行散射测量，同时应用这两种理论计算了超光滑表面粗度均方根值，从计算结果来看，两种理论所得结果与WYKO测量结果吻合较好。     

结合自适应雾气估计的快速单幅图像去雾

大气中水分子及微小颗粒对光的散射和吸收,使得在雾天条件下获取的图像严重降质,本文提出一种结合自适应雾气估计的快速单幅图像去雾算法。首先,该算法从大气散射模型出发,通过分析景深与亮度分量之间存在的相关关系,提出线性系数利用亮度分量来近似估计出景深,并通过最小滤波对明亮区域进行修正,得到粗略透射率;其次,观察到散射系数值与雾浓度呈正相关,从而结合雾浓度模型与指数函数提出自适应散射系数概念,估计出较准确的透射率;最后,根据大气散射模型复原出无雾图像。实验结果表明本文算法可以复原出清晰自然的无雾图像,明显提高了图像可见度,且具有较低的时间复杂度。     

前向散射仪测量能见度的原理和标定方法探讨

本文探讨了前向散射仪器测量水平能见度的基本原理，并设想了一种在自然条件下简单易行的标定方法。     

基于有效散射单元模型的全波形LiDAR数据可变分量分解

当前全波形LiDAR数据的分解方法仅考虑波形拟合,不能充分反映地物目标的散射特性。针对这一问题,提出利用有效散射单元表达全波形LiDAR数据,并对全波形LiDAR数据进行基于有效散射单元模型的可变分量波形分解。对ICESatGLAS全波形数据进行实验,实验结果能得到较为准确的地物高程信息;同时结果所得的有效散射单元个数与对应地物散射面积相结合,可反演各类地物散射特性。方法在自动确定地物个数的同时,从全波形LiDAR数据形成机理上设计分解模型,为全波形LiDAR数据分解建模提供了有效的新思路。     

磁偶极子的定位模型及实验验证

磁偶极子模型被广泛应用于目标物体定位及状态测定应用中,本文讨论了磁偶极子标量模型的推导.并设计了磁传感器模块对其进行验证.在实际位置检测应用中,当检测距离并不远远大于目标体体积的情况下,理想的磁偶极子模型便不能成立,本文基于该标量模型和磁传感器模块,对于在实际应用中理想磁偶极子模型在检测距离变化时的成立条件,并通过Cm实验进行验证,深入研究了磁偶极子理想模型在定位过程中的应用,提出检测磁偶极子模型在距离检测应用中的有效性的检测方法.     

雾状气溶胶衰减8～14微米红外波段的建模分析

雾状气溶胶对红外辐射有着强烈的散射和吸收,对以8~14μm波长为载体的多种光波技术有重要影响。采用有限体积法,将气溶胶视为吸收、各向异性散射的非灰介质,考虑多重散射的影响,建立了8~14μm波段红外辐射在气溶胶中衰减的计算模型;同时在窄谱带模型的基础上,利用Mie散射理论计算窄谱带内的平均光学系数。应用蒙特卡洛法与有限体积法作对比,验证了模型的正确性;用朗伯比尔定律与有限体积法作对比,证明前者因未考虑多重散射及介质自身辐射而精度不高。     

超镜因子对会聚导管输运特性的影响模拟

针对水平散射几何中子反射谱仪中导管设计的客观要求,采用Mcstas模拟计算软件对会聚导管内表面超镜因子的不同选择模型进行了模拟计算,获得了不同超镜因子组合模型聚焦导管的中子传输特性。由于水平散射几何中子反射谱仪对中子束流水平方向发散要求比较严格,导管水平面的超镜因子可选用较大的超镜因子m=3,垂直面的超镜因子可根据要求的发散不同,选择超镜因子小于3的超镜或吸收材料。不同组合设计模型模拟计算结果可为中子散射谱仪设计中子导管以及内表面超镜因子的选择提供理论参考。     

双口网络S参数测量误差校正分析及应用

采用误差分析及校正模型,讨论用数值分析的方法去除系统误差,降低随机误差的思路,其目的是消除标量网络分析仪在测量过程中的系统误差,提高测量精度。理论计算和实际测量结果表明,测量精度明显提高。该误差分析理论及误差测量方法在标量网络分析仪中得到应用,提高了仪器的性能。     

轴承沟道分选机器人伺服系统的定位研究

轴承沟道分选机器人机械手的定位控制要求快速、平稳和精确.建立机械手运动学模型,给出伺服系统的分段减速方法,从而获得高性能的定位控制;利用DSP强大的运算处理功能,通过SVPWM方法实现永磁同步电动机的定位控制,并给出低频下的标量补偿,保证定位过程在低频时电动机的带载性能.实验证实了理论计算的正确性.     

Statistic optics discussion on the formula of digital holographic 3D surface profiling measurement

Based on the theories of statistic optics and scalar diffraction, this paper derived the digital holography formula for 3D object surface profile measurement. The results indicate that random changes of the scattering light phase will cause error in measurement when the detected object surface is optically rough. Moreover, more precise calculation formula should theoretically be used in case of there is a short distance between the CCD and the measured object, both for a smooth object and an optically rough object.     

Phase reconstruction for speckle fields of light-induced scattering in a LiNbO<Subscript>3</Subscript>:Fe crystal

Reconstructing the phase distribution of scalar speckle fields arising under light-induced scattering in a photorefractive LiNbO₃:Fe crystal is considered. A phase distribution reconstruction method based on simultaneous processing of two interferograms obtained for orthogonal planes of converging reference and signal beams is proposed. The method is more advantageous than single-interferogram methods for analyzing interferograms in the frequency domain because it enables to reduce the number of false-detected optical vortices and increase the SNR in phase reconstruction.     

Characterization of dual-periodic structures with optical scattering

Laser scattering method as a non-contact method provides an opportunity to real-time monitor the evolution of periodic nanostructures during fabrication, e.g. when the surface is irradiated with a focused ion beam. Using the method, the diffraction angle needs calibrating according to the grating equation. In this paper, we used scalar analysis to demonstrate the use of a dual-period structure for formation of dual spectral peaks at the 1st diffraction order. We then made use of numerical study based on rigorous coupled-wave analysis to optimize these Al-grating structures in terms of depth. It is found that dual-peak wavelengths can be selected by using different angles of incidence and low-loss reflection is obtained using an optimized structure. It is further proposed that these wavelengths can be used to determine the diffraction angle during fabrication without the need for pre-calibration of an optical scattering system.     

离子辅助制备碳化硅改性用硅膜的研究

本文介绍了一种利用霍尔型离子源辅助电子束蒸发，在碳化硅（Silicon Carbide: SiC）材料上制备硅改性薄膜的方法，研究了不同沉积速率下改性后的抛光效果。对样品进行了表面散射及反射的测量。通过样品的显微照片可知硅膜层在沉积速率增大条件下结构趋于疏松。通过精细抛光改性的反应烧结碳化硅（Reaction Bonded Silicon Carbide: RB-SiC）样品表面散射系数减小到1.46%，反射率接近抛光良好的微晶玻璃。温度冲击实验和表面拉力实验表明硅膜无龟裂和脱落，性质稳定，与碳化硅基底可以良好的结合。     

Magnetic circular dichroism in EELS: towards 10 nm resolution

We describe a new experimental setup for the detection of magnetic circular dichroism with fast electrons (EMCD). As compared to earlier findings the signal is an order of magnitude higher, while the probed area could be significantly reduced, allowing a spatial resolution of better than 40 nm. A simplified analysis of the experimental results is based on the decomposition of the mixed dynamic form factor S(q-->,q-->('),E) into a real part related to the scalar product and an imaginary part related to the vector product of the scattering vectors q--> and q-->('). Following the recent detection of chiral electronic transitions in the electron microscope the present experiment is a crucial demonstration of the potential of EMCD for nanoscale investigations.     

Imaging periodic surface relief structures

Because of shadowing, multiple scatter and polarization effects, the interpretation of images of gratings with fine periods, isolated deep structures, and multiple scattering volume objects is seriously complicated. In this paper a review of the methods used to model such effects is presented. Periodic surface relief gratings are of particular current importance because of the possibility of producing calibration samples using them. Several examples which illustrate electromagnetic volume effects are examined. General trends which help in validating the use of Fourier-transform-based scalar transmittance theory are then indicated. The angular spectrum approach, which can be used, together with a scatter function generated using the rigorous electromagnetic theory, to calculate coherent, partially coherent and confocal images of volume objects, is also discussed.     

A multiresonance method for measuring the reflection coefficient in a waveguide

A new method for measuring the complex reflection coefficient in rectangular waveguides using a scalar network analyzer is proposed. This method is based on measurements of the resonance characteristics of a quasi-resonator, i.e., a portion of the waveguide between a reflecting object on one side and an object with a known scattering matrix on the other side. One advantage of the multiresonance technique is that simultaneous analysis is performed for the entire set of resonance frequencies, which substantially increases the accuracy in finding the reflection coefficient. The errors in measuring the magnitude and phase of the reflection coefficient in actual experiments were close to 0.015 and 1.5°, respectively.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 94–100.Original Russian Text Copyright © 2004 by Ponomarenko, Popov.     

ECC算法的功耗分析研究

随着旁道攻击方法的提出,在安全领域,就要求各类密码算法在实际应用时需要考虑抵抗此类攻击的能力.利用Simplepower功耗分析工具,对椭圆曲线密码(ECC)加密算法在GF(2m)域上的Montgomery标量乘法进行了抵抗,简单功耗分析(SPA)和差分功耗分析(DPA)的研究.结果表明,目前常用的Montgomery算法具有较好的抵抗SPA攻击的能力,但是对DPA攻击防护不够,从而得出ECC算法的实际应用还需要额外添加抗差分功耗分析的方法,以增强其抵抗DPA攻击的能力.     

广州中心城区冬季大气气溶胶消光特性观测研究

2013年12月利用广州市大气超级站气溶胶吸收系数、散射系数、污染物及气象观测数据,分析了广州冬季大气消光组成变化及其影响因子。观测期间,黑碳浓度均值为6．98±3．71μg／m^3,气溶胶吸收系数均值为60．04±30．72Mm^-1,气溶胶散射系数均值为363．51±182．18Mm^-1,单次散射反照率均值为0．85±0．04。在总消光系数中气溶胶吸收消光占13％,气溶胶散射消光占81％。气溶胶吸收系数与散射系数日变化均呈双峰结构,这与人类活动和气象条件的改变有关。通过最大频数拟合得到广州冬季气溶胶吸收系数和散射系数本底值分别为32．93Mm^-1和281．82Mm^-1。气溶胶散射系数和吸收系数与PM2.5质量浓度呈线性正相关,与大气能见度呈指数负相关。通过测量气溶胶消光和气体消光分量加和获得的消光系数与能见度仪消光系数变化趋势基本一致,降雨及较高相对湿度对能见度仪消光系数影响较大。