AOTF相机成像过程中的图像畸变分析及校正研究北大核心CSCD

针对声光可调谐滤波器(AOTF)自身固有的因声光互作用导致的成像畸变问题,利用AOTF的解析表达式和几何像差公式对AOTF相机的畸变特性进行分析,建立了声光互作用图像畸变模型,给出了各畸变系数随入射光传播角的变化关系;并在所构建畸变模型的基础上,结合两步标定法和双线性内插法对畸变图像进行校正分析。实验结果表明,未加AOTF相机系统拍摄图像的最大畸变像素位移量为1.6pixel,加AOTF相机系统拍摄图像的最大畸变像素位移量为9.0pixel,畸变校正后的最大畸变像素位移量为1.4pixel,优于未加AOTF相机系统所拍摄的图像。该畸变模型较好地描述了AOTF相机的畸变产生机理及特性,该方法可以有效地解决AOTF相机成像过程中的图像畸变问题,在AOTF光谱相机的精确测量方面将有较好的应用前景。     

近红外非共线声光可调谐滤波器设计理论的选取方法

根据对二氧化碲声光材料特性的不同考虑,存在几种不同的非共线声光可调谐滤波器(AOTF)设计理论。分析和比较了3种常用的非共线声光作用关系,研究结果表明,在近红外波段,P.A.Gass非共线声光作用关系能较准确地反映AOTF各参数之间的关系。选取P.A.Gass理论作为设计基础,针对0.8~2.0μm非共线AOTF,阐述了入射光极角选择、色散补偿以及几何参数选择等优化设计方法;给出了0.8~2.0μm非共线AOTF的设计参数,理论计算各项性能指标保持在较好水平,表明了P.A.Gass理论对该波段AOTF设计的适用性。对于推进近红外非共线AOTF的广泛应用具有指导意义。     

TeO2晶体旋光性对其分光特性的影响分析

TeO2是声光可调滤波器主要成像晶体,由于晶体本身在分光成像时会产生色差,漂移等问题,文中从基础理论出发,研究了TeO2 晶体的旋光性对其作为声光可调滤波器时分光特性的影响,进而对其基本参数作了优化。首次对比分析了I.C.Chang理论体系与P.A.Gass修正理论体系,通过对比分析方法,得出在红外波段,两种理论体系对于超声波频率协调关系的计算结果差异较大,作者认为是I.C.Chang理论忽略晶体旋光特性所引起,因此,以P.A.Gass理论作为基础的声光可调滤波器设计方法适用于红外波段,当入射光极角小于30时,其旋光特性对分光性能的影响较小。通过对比分析可知,设计的入射光极角应小于54.7,这样可以保持较高的声光优值和较低水平的超声波频率;在红外波段,设计的入射光极角应小于39.2,两频率协调关系偏差f较小。     

一般相位匹配条件下声光可调谐滤波器系统的理论分析

研究非共线性声光可调谐滤波器(AOTF)在一般相位匹配条件下的声光相互作用关系。对于通常设计制造的声光可调谐滤波器,它的o光和e光具有不同的波长,应用中无法同时使用此两束衍射光,为了使可用光强增大,应当使两束衍射光的波长相等。研究了使一般声光可调谐滤波器晶体两束衍射光波长相等的方法。对于未按照等值点理论制造的声光可调谐滤波器晶体,可以使入射光与晶体表面的法线成一个小的角度,根据一般相位匹配原理可以使两束光的出射波长相等。在实验中证明此方法的正确性,此角度称为等值偏置角。对于不同数值的衍射波长,有不同的等值偏置角,最后给出了等值偏置角随衍射波长的变化规律。     

Wollaston棱镜对发散光束的分束特性分析

为了了解Wollaston棱镜用于发散光束时对出射o光束、e光束发散角的影响,利用折射定律对发散光束两边缘光线通过Wollaston棱镜后的o光、e光分束角进行了推导,采用控制变量法分析了发散光束经过Wollaston棱镜后出射的o光束和e光束的变化,得出了Wollaston棱镜对出射o光束、e光束发散角的影响。结果表明,相对入射光束的发散角,Wollaston棱镜对o光束有减小发散角的作用,对e光束有增大发散角的作用;对于一定结构角的棱镜,当入射光的波长变大时,o光束发散角增大,而e光束发散角减小;对于确定的单色发散光束,当结构角增大时,o光束发散角减小,而e光束发散角增大;无论是入射光的波长还是棱镜结构角的变化,对出射o光束、e光束发散角的影响都是有限的。由此可见,在要求不是太高的应用中,可以忽略Wollaston棱镜对出射o光束、e光束发散角的影响。     

钒酸钇Wollaston棱镜分束特性分析

为了解钒酸钇Wollaston棱镜的分束特性,通过棱镜中的光路分析,得到光束正入射时o光光束和e光光束的分束特性公式,并用MATLAB软件拟合得到棱镜的分束特性关于入射光波长和结构角的变化关系曲线。结果表明,对于一定结构角的棱镜,其分束角具有明显的色散特性,波长越短,分束角越大,且变化也越快,在红外光谱范围,波长对棱镜分束角的影响减小,其分束角趋于稳定;分束角的对称性受波长变化的影响较小,应用中可以忽略。棱镜的结构角与入射光波长对棱镜的透射比均有影响,当棱镜的结构角一定时,透射比随入射光的波长呈振荡性变化,且o光透射比的光谱效应更为明显。该研究可以为棱镜的设计制作和实际使用提供有价值的参考。     

一种新颖的宽带可调谐掺钛蓝宝石激光器

本文报导一种能充分利用掺钛蓝宝石本身的色散能力，作为调谐及压缩线宽的掺钛蓝宝石激光器，谐振腔采用梯形棱镜掺钛蓝宝石晶体和两块ＺＦ６的色散棱镜压缩线宽并构成调谐系统，用三块输出镜，实现了２６５．３ｎｍ的调谐范围；泵浦光能为８５ｍＪ／ｐｕｌｓｅ时，在７６２．６ｎｍ处得到１１．８ｍＪ／ｐｕｌｓｅ的最大光能输出，光一光转换效率达１３．９％。     

基于不同介质材料的AOTF特性研究综述

基于不同介质材料的AOTF(声光可调谐滤波器)具有不同的性质及应用场合.目前应用于紫外、可见光和红外波段的AOTF主要以α-SiO2、TeO2和TAS( Tl3AsSe3)为介质.为了得到性能更优的AOTF,人们一直在探寻新型双折射晶体材料来代替α-SiO2和TAS.文章汇总并讨论了近年来人们针对基于TeO2、KDP(...     

电可调谐的聚合物液晶光子晶体

设计了一个无顶的（top-cut）六角棱镜,棱镜高h=3.73cm ,侧面与底面夹角alfa=66 。利用此棱镜和光全息刻蚀的方法,在光抗材料上制作了对称六角结构、蜂窝结构和椭圆柱非对称等结构的光子晶体;并且在聚合物分散液晶材料上制作了大面积电可调谐的光子晶体结构。该光路系统结构简单、稳定、重复性好。光子晶体的理论干涉模式和实验制作结构相比较,结果吻合的非常好。另外还研究了光子晶体的远场衍射模式和电转换特性,对称的六角衍射模式更好的揭示了光子晶体的六角结构。晶体结构中液晶微滴（droplet）的尺寸最小可到10nm,直流转换电压最小达到13.3V/?m。这对研究电调谐的光子晶体激光器和电光转换装置有非常深远的意义。     

介质的吸收对掠射法测量折射率的影响

通过研究光经过棱形吸收介质后的出射角,可以获得掠射过程中出射角与入射角、复折射率实部和虚部的关系.通过数值模拟计算可知,当棱镜顶角和折射率一定以及虚部越大时,吸收棱镜与透明棱镜的出射角之差越大,对反演计算出的折射率的影响也越大;当顶角为π/3以及吸收虚部分别为0.20、0.10和0.01时,计算出折射率的最大相对误差分别约为5.0％、2.5％和0.2％;当虚部一定时,在较小的出射角的情况下,大顶角棱镜所产生的误差较小,在大出射角的情况下,小顶角棱镜产生的误差较小.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks