红外预警卫星直视地表波段选择及探测能力

建立了红外预警卫星直视地表（See-To-Ground,STG）波段探测能力计算模型,并仿真研究了STG最佳探测波段范围以及该波段在导弹预警中可能具备的能力。首先建立了固体、液体导弹尾焰红外辐射模型、地球/大气环境特性模型、点目标辐射通量表观对比度模型、预警卫星系统噪声模型和最低探测高度模型;其次,利用上述模型分析了固体和液体导弹尾焰的表观对比光谱分布规律,认为将STG波段选定为2.86~3.0 m最具合理性;然后,通过分析液体和固体导弹尾焰在该波段的表观对比度光谱随高度的变化规律,初步探讨了STG波段的导弹探测能力;最后,通过分析不同条件下预警卫星对导弹的首次探测高度,系统研究了SBIRS-GEO预警卫星在STG波段的探测能力。研究结果表明:STG波段对固体导弹则具有较强的早期预警能力,而对液体导弹的早期预警能力则相对较弱。     

红外预警卫星最佳探测波段分析

为解决红外预警卫星在近中红外的最佳探测波段问题,采用建模仿真的方法获得了2～5μm波段范围内不同高度条件下火箭尾焰目标的红外辐射光谱特性,利用MODTRAN软件包计算了典型大气条件下同样波段范围内不同高度处的大气透过率和地球/大气背景红外辐射光谱特性,在此基础上计算了目标背景之间的对比度.通过分析目标背景对比度的变化规律可知:随着飞行高度的增加,目标背景对比度会先增大后减小,但无论在什么飞行高度,2.63～2.83μm和4.18～4.50μm波段的目标背景对比度都较大,比较适合目标探测,并且这两波段还具有更加精细的波段结构,实际应用中可根据探测需求选择更小的波段范围并确定相应的中心波长.     

尾焰红外辐射特性的反向蒙特卡罗法模拟

以发动机尾焰的红外探测为主要应用背景,利用反向蒙特卡罗法计算了液体火箭发动机尾焰红外辐射特性。首先计算了尾焰红外辐射在2.7μm下的轴向分布特性及空间不同角度分布特性,计算结果较为合理。重点计算了尾焰2~5μm的光谱辐射特性,并考虑了大气衰减的影响,与TheAerodyne Radiation Code的计算结果趋势吻合良好。实际探测时,探测器只能接收到尾焰辐射的小部分能量,因此对一定距离下探测器接收辐射进行计算,进而获得尾焰在探测器视场内的红外光谱辐射分布特性,具有重要的理论意义和实际应用前景。     

导弹预警卫星探测原理及其攻防技术探讨

导弹预警卫星通过对弹道导弹尾焰红外辐射的探测实现主动段对弹道导弹的跟踪预警。从大气吸收的角度出发,对导弹红外预警卫星的探测原理进行了研究,通过计算说明了卫星对导弹尾焰进行红外探测的波段选择依据,并从探测距离上对该红外预警卫星的探测能力进行了建模研究。探讨了对光学探测卫星实施干扰时需要解决的问题以及卫星可能采取的防护方法。     

亚像元火点对红外预警卫星的辐射干扰特性

亚像元火点是红外预警卫星的辐射干扰源,基于推导火点像元辐射强度方程,对不同条件下的火点像元在2.55～2.85μm波段和4.19～4.48μm波段的辐射强度进行数值计算,分析了影响火点像元辐射特性的因素.通过与TitanⅢB型火箭尾焰辐射特性进行对比分析并利用实际火点数据验证了亚像元火点的辐射干扰特性,结果表明:亚像元...     

高速飞行目标尾焰红外辐射特性的建模仿真计算

飞行器目标的尾焰红外辐射特性对目标的红外探测、识别和跟踪具有极其重要的作用。为了分析尾焰的红外辐射特性,首先根据经验公式计算出尾焰的流场分布,然后使用窄带模型计算出谱带的光谱吸收系数和透过率;对于非均匀热气体,考虑到碰撞展宽效应和多普勒展宽效应,使用C-G谱带传输模型得到飞行器尾焰2~5 μm的红外辐射分布。最后, 计算了不同组分的尾焰红外辐射特性,分析了组分分布和大气传输对尾焰红外辐射特性的影响,为探测波段的选择提供了参考依据。     

探测天顶角与太阳天顶角对卫星红外探测的影响

为了分析不同探测环境对卫星红外探测的影响,推导了倾斜探测路径下目标与背景在探测器入瞳处的辐照度对比度计算公式。计算了目标在海天背景下不同温度、不同高度、不同太阳天顶角、不同探测天顶角条件下,目标与背景在0.75~14μm波段的红外单色辐射照度对比度。分析指出:太阳天顶角对红外探测的影响主要在2.7μm以下波段,探测波长大于2.7μm可不考虑太阳的影响。目标在5 km以下、探测天顶角在60°以上继续增加时,探测波段变窄,不可探频段增宽;目标在10km以上,探测天顶角变化对探测影响很小。这些结论可用于指导卫星红外探测波段选择与探测结果分析。     

导弹主动段天基紫外探测像面照度建模与仿真

分析了导弹尾焰紫外辐射原理和能量传递方程,结合导弹主动段运动方程,建立了尾焰紫外辐射模型。考虑大气透过率和地球背景亮度的影响,得到导弹主动段尾焰紫外辐射与探测器像面辐照度关系。基于SBIRS-GEO 预警卫星的探测仿真,比较了不同探测波段下高、低弹道尾焰紫外辐射的像面辐照度变化。结果表明:紫外辐射在大气中的传输特性是影响像面辐照度变化的主要因素;相比于300~400 nm 波段,200~300 nm 波段可以提早发现目标、降低发现高度,更适宜作为探测波段。     

临近空间高超声速飞行器红外辐射特性分析

为了对临近空间高超声速飞行器进行有效探测和预警,以X-51A为例,计算火箭助推段、超燃发动机工作段和无动力滑翔段、飞行器蒙皮、喷管和尾焰的双波段红外辐射特性。红外辐射计算的关键在于温度和有效辐射面积的确定。根据修正Lees驻点热流密度方法和辐射平衡时的辐射传热公式,计算出蒙皮的温度。用加力燃烧的涡喷发动机模型近似计算喷管的温度。把导弹尾焰温度分布场模型进行三段式简化,模拟出尾焰的红外辐射特性。仿真结果表明,在X-51A的不同飞行阶段,从不同探测角度观察到的各辐射部位对总体红外辐射贡献率差异较大;速度对蒙皮的红外辐射影响较大,而喷管和尾焰的红外辐射与火箭和超燃冲压发动机的燃烧状态有关。分析指出,当高超声速飞行器飞行姿态发生变化,或者在不同的飞行阶段,更适合采用双波段进行探测。     

卫星姿控推进器尾焰红外辐射的数值模拟

为全面了解卫星的红外辐射特性,需掌握卫星姿控推进器尾焰的红外辐射特性.按照先计算尾焰的流场、再计算尾焰的吸收系数、最后用有限体积法求解尾焰的红外辐射亮度的逻辑顺序,较完整地建立了卫星姿控推进器尾焰红外辐射的求解模型;根据该模型计算得到尾焰的辐射亮度,进一步求解获得了1000～4500cm-1内的光谱和波段辐射强度.通过...     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.