第三讲:红外隐身性能测试与计量

光电隐身一般包括红外隐身、激光隐身、可见光隐身、雷达隐身和声波隐身.本讲座较系统地介绍红外隐身、激光隐身、可见光隐身的技术内涵,光电隐身技术的应用和国内外发展现状,隐身原理和隐身措施.重点介绍光电隐身的性能评估,包括性能评价方法和模型,隐身性能测试,隐身性能测试仪器的计量检定和校准等.     

Terahertz-wave generation by surface-emitted four-wave mixing in optical fiber

We propose a novel terahertz-wave source through the four-wave mixing effect in a conventional single-mode optical fiber pumped by a dual-wavelength laser whose difference frequency lies in the terahertz range. Surface-emitted geometry is employed to decrease absorption loss. A detailed derivation of the terahertz-wave power expression is presented using the coupled-wave theory. This is a promising way for realizing a reasonable narrow-band terahertz-wave source.     

光电对抗仿真系统研究

介绍了光电对抗在信息化战争中的地位与作用,阐述了光电对抗仿真系统研究的必要性,针对国内外光电对抗仿真的研究现状,给出了光电对抗仿真系统的总体框架,研究了光电对抗仿真需解决的关键技术和需要完成的主要工作,最后对我国光电对抗仿真系统的研究进行了总结。     

用于激光雷达的相干合成光束研究

提高激光雷达对空间小目标探测能力的重要手段是增大发射到目标上的光强,激光相干合成是在目标上获得较大光强的有效途径.为了评价相干光束在目标上的合成效果,引入了适合空间小目标探测的相干合成效果评价参数(合成效果因子),在此基础上讨论了光束相干合成效果的影响因素.研究表明: 合成效果因子随合成光束束腰间距的增大呈周期振荡变化,振荡幅度逐渐减小;达到理想合成效果需要的光束传输距离随光束间距的增大而增加,这对设计相干合成系统光束束腰间距具有参考意义.同时,还研究了光束的相位控制精度与合成效果之间的关系. 结果表明:当相位控制精度达到π/4时,合成效果可以达到理想效果的80%;当相位控制精度为π/2时,合成效果降为理想效果的50%.研究还表明,激光偏振方向不平行对合成效果的影响不明显. 关键词： 相干合成 激光雷达 合成效果     

基于MDA法计算水雾粒子红外隐身粒径

水雾隐身技术是一种较为理想且经济适用的目标特征信号控制技术。本文从辐射传输方程出发,考虑水雾粒子的本身辐射和散射,提出以红外表观透射率评价水雾粒子的红外隐身性能。应用Modified Differential Approximation(MDA)法结合MIE理论,计算了水雾粒子红外表观透射率随水雾粒子浓度和粒径的变化关系,得到水雾粒子最佳红外隐身粒径。结果表明:水雾粒子的红外表观透射率随粒子浓度的增加而减小,但当粒子的浓度增加到一定值时,红外表观透射率基本保持不变;水雾粒子的红外表观透射率随粒径的增加先减小后增大,当探测波段为3～5μm时,水雾粒子的最佳红外隐身粒径为6μm;而探测波段为8～12μm时,水雾粒子的最佳红外隐身粒径为12μm。     

A novel simulation method to evaluate the collection performance of a monolithic active pixel sensor

A novel simulation method is presented in this paper to evaluate the collection performance of monolithic active pixel sensor (MAPS) devices for minimum ionizing particle tracking. A simplified 3D matrix pixel structure is built using the computer aided design software Sentaurus. The virtual device is then divided into hundreds of parts and an independent customized X photon model is involved in each part to simulate the conditions under ⁵⁵Fe radiation. After data processing and analysis, charge collection efficiency, collection time and diffusion conditions can be estimated in detail. In order to verify the reliability of the method, comparisons are made between the simulations and experiments. Although there are some defects, it can be concluded that the proposed idea is a feasible method for the evaluation of the MAPS collection performance.     

Study on induced radioactivity of China Spallation Neutron Source

China Spallation Neutron Source (CSNS) is the first High Energy Intense Proton Accelerator planned to be constructed in China during the State Eleventh Five-Year Plan period, whose induced radioactivity is very important for occupational disease hazard assessment and environmental impact assessment. Adopting the FLUKA code, the authors have constructed a cylinder-tunnel geometric model and a line-source sampling physical model, deduced proper formulas to calculate air activation, and analyzed various issues with regard to the activation of different tunnel parts. The results show that the environmental impact resulting from induced activation is negligible, whereas the residual radiation in the tunnels has a great influence on maintenance personnel, so strict measures should be adopted.     

新课程背景下改进物理实验教学的实践与思考

物理新课程标准要求物理实验贴近学生生活,加强课程与学生生活和现实社会的联系.实验是培养学生动手能力的最佳途径,因此要尽可能地创造条件和不断改进,让学生亲自动手实验.笔者结合自己的实践与思考通过几个实例谈些关于新课程实验改进的做法.     

可拆变压器在课堂教学中的应用

可拆变压器是高中物理教学中常见的实验器材;利用它设计一些趣味小实验,既可以活跃课堂气氛,又利于学生对物理知识的理解.1实验一:比一比谁的力气大实验器材:可拆变压器,学生电源,导线.实验过程:(1)将可拆变压器固定旋钮取下,使变压器横