Harmonic beam splitter design and fabrication

Two problems of half-wave hole and high ripples in the transmittance region for a harmonic beam splitter had been pointed out and analyzed. Based on the application of a half-wavelength control and a new admittance matching methods, a harmonic beam splitter was designed and fabricated. The former method eliminated the half-wave hole fundamentally, and the latter smoothed high ripples in the transmittance region effectively. The matching stack consisted of a symmetrically periodic structure and provided a complete matching at the desired wavelength, i.e., both conditions for the equivalent admittance and phase thickness were fulfilled. Furthermore, both the theoretical and the tested curves had been given, and a good agreement between them was obtained.     

Non-contact thickness measurement for ultra-thin metal foils with differential white light interferometry

A new differential white light interference technique for the thickness measurements of metal foil is presented. In this work, the differential white light system consists of two Michelson interferometers in tandem,and the measured reflective surfaces are the corresponding surfaces of metal foil. Therefore, the measuring result is only relative to the thickness but not the position of metal foil. The method is non-contact and non-destructive, it has the advantages of high accuracy, fast detection, and compact structure. Theoretical analysis and preliminary experimental verifications have shown that the technique can be used to measure the thickness of foil in the range of 1 to 80 μm with accuracy better than 0.08 μm.     

HL-2A装置硅化对杂质线辐射的影响

在2004年的实验中，首次在HL-2A偏滤器装置上进行了硅化器壁处理，在这种硅化器壁的条件下，对轻重杂质的线辐射进行了研究，并与无硅化条件下的杂质特性作了比较。在实验中，通过观测杂质的辐射特性研究了硅化对杂质的吸附作用和硅化效果的维持。并通过调整硅化后的辉光放电清洗，研究了硅化对氢再循环的影响。     

Generation of UV laser light by stimulated Raman scattering in D2, D2/Ar and D2/He using a pulsed Nd:YAG laser at 355nm

A pulsed Nd:YAG laser at 355nm is used to pump Raman cell filled with D_2, D_2/Ar and D_2/He. With adequately adjusted parameters, the maximum photon conversion efficiency of the first-order Stokes light (S_1, 396.796nm) reaches 33.33% in D_2/Ar and the stability of S_1 in pure D_2 is fairly high, the energy drift being less than 10% when the pump energy drifts in the range of 5%. The conversion efficiency and stability, which are functions of the composition and pressure of the Raman medium and the energy of pump laser, are investigated. The result has been used to optimize the laser transmitter system for a differential absorption lidar system to measure NO_2 concentration profiles.     

声纳技术及其在军事上的应用

 水声学是指以水波为对象研究水下通信、数据传输、目标检测和定位、识别、导航等方面的一门独特的科学。到目前为止,声波还是惟一能在深海中作远距离传输的能量形式,故它在军事上有着重要的用途。于是探测水下目标的技术---声纳技术便应运而生。所谓声纳(Sonar,SoundNavigationAndRanging的缩语),其原意是“声音导航和测距”的意思,是利用声波在水下进行侦察的工具。本文将给大家介绍一下水声探测技术的基础知识、声纳的工作原理及其在军事上的应用。一、水声探测技术的基础知识大家知道声波是一种弹性波。     

声诱饵仿真试验系统

文章介绍了声诱饵仿真试验系统中的有关问题，包括：系统的组成、工作原理、对接装置结构等。建立了对接装置声耦合状态下的数学模型，对近场声压分布进行了仿真计算，得出了匹配材料厚度、发射和接收换能器的选取原则。     

有趣的数字

自从有了人类,就有了数数和记数的需求,于是就产生了数字。数字就是用来记数的符号。罗马数字是罗马人创造的。中国数字是中国人创造的。但是,阿拉伯数字不是阿拉伯人创造的,而是印度人创造的,现在已经成为世界各国的通用数字。 数学是研究数量关系和空间形式的一门学问。它具有基础和工具的作用,被誉为“科学大门的钥匙”和     

奇妙的惯性力

实际的参考系都不是惯性系，因此必须考虑惯性力．     

Short pulse propagation in dense dispersion compensated systems

The short Hermite-Gaussian optical pulse transmission over 1440 km in a dense dispersion compensated system is investigated based on numerical simulation. In the simulation, compensation is made not only for the group-velocity dispersion but also for the third order dispersion. It is demonstrated that the pulse with reasonably lower power can propagate steadily in net zero, positive and negative dispersion system.     

非晶金刚石膜的性能及其应用

非品金刚石薄膜具有超高硬度等一系列优异的特殊性能，为工程界孜孜追求的材料表面镀膜。用百纳科技公司研发制造的过滤阴极真空电弧离子镀膜机镀制的非晶金刚石薄膜，SP^3金刚石结构量≥80％，硬度高，膜／基结合力高，摩擦系数小，耐磨损，耐腐蚀，透光率高，在电子，机械，光学，生物医学上有广泛应用前景。我们已在视窗玻璃，丝锥，模具，硬质合金刀头等产品上成功应用。