堆泵浦3He-Ar-Xe激光体系小信号增益与效率实验研究

介绍了CFBR-Ⅱ堆泵浦3He-Ar-Xe体系1.73μm波长激光小信号增益和泵浦效率的实验研究.在脉冲峰热中子注量率为6.9×1014cm-2.s-1、3He、Ar、Xe气体的比例为80.219.30.5,总压强为8.3×104Pa时,采用透射率从1.7%到10%的6个谐振腔输出镜均获得了激光输出.在谐振腔输出镜透射率为7%时,得到了激光脉冲峰功率为45mW,其对应的激光泵浦效率为1%.在此基础上,利用Rigroa分析方法拟合出3He-Ar-Xe体系激光的小信号增益为0.24%/cm,饱和光强为36W/cm2.     

Microstructures of laser cladding of intermetallic-ceramic composite coatings

The microstructures of laser cladding of (Ni-24.5%(atom fraction)Al)+5O%(mass haction)WC coatingsbefore and after aging was comparetively studied by using SEM and TEM. It is shown that dissolving of WC and reprecipitating in the forms of WC and W,Coccurred during laser cladding, and intermetallic γ' (Ni3Al) orderly precipitatefrom metastable supersaturant Ni-matrix solid solution after heat treatment. The structures are favorable for coating'sproperties.     

激光三角法位移传感器测头设计

本文以直射式激光三角测头为例,导出了满足Scheimpfiag成象条件下的待测面位移与象位移间的准确关系,作为仪器结构参数设计的基础,并对提高测量精度和实用性的各项改进设计进行了分析。     

小议科技论文英文摘要的撰写

英文摘要是现代科技论文的必要附加部分。本文针对英文摘要的结构和内容进行了总体的论述,并举例说明了其时态、人称、语态及常用表达法等方面的写作技巧。     

纳焦飞秒激光在有机材料表面刻划微结构光栅的研究

使用振荡器产生的飞秒激光在透明有机材料PMMA表面进行了刻划微结构光栅的研究．通过理论分析得到了飞秒激光参数和平台移动速度对线宽的影响，进行了系统的加工实验，加工结果与理论分析基本吻合．在透明有机材料PMMA表面进行了多种光栅的刻划，并对刻划的光栅进行了衍射和色散测试，调整光栅的尺寸和排列方式，得到了形状各异的衍射图案。     

基准离焦偏差控制技术

一种新的采用基准离焦信号的针孔调焦方案,用于激光直写的自动对焦子系统。通过在离焦曲线上提取参考离焦信号,建立基准离焦判据,它能容易地区分前离焦或后离焦,有效地克服了原有针孔调焦方案难于根据离焦信号来分辨离焦方向的弱点。借助微处理器和模拟电路实现了这一方案,并因此获得了均匀的1靘线宽的线条。     

身体叙事在中国的演变

身体叙事是中国20世纪末最重要的文化现象。本文通过对陈染林白和卫慧棉棉为代表的女性写作的考查，探讨西方随着哲学的肉身化不断推进的身体叙事，如何从陈染们的以“身体”为中心的反抗，堕落为棉棉们的消费文化的过程，以期促进对中国现阶段文化现象的认识。     

Pulsed Laser Precision Length Measurements

The paper discusses mode locking use in pulsed lasers for precision measurement of large lengths.     

Emissivity Measurements on Metallic Surfaces with Various Degrees of Roughness: A Comparison of Laser Polarimetry and Integrating Sphere Reflectometry

Both integrating sphere reflectometry (ISR) as well as laser polarimetry have their advantages and limitations in their ability to determine the normal spectral emissivity of metallic samples. Laser polarimetry has been used for years to obtain normal spectral emissivity measurements on pulse-heated materials. The method is based on the Fresnel equations, which describe reflection and refraction at an ideally smooth interface between two isotropic media. However, polarimetry is frequently used with surfaces that clearly deviate from this ideal condition. Questions arise with respect to the applicability of the simple Fresnel equations to non-specular surfaces. On the other hand, reflectometry utilizing integrating spheres provides a measurement of the hemispherical spectral reflectance, from which the normal spectral emissivity can be derived. ISR provides data on spectral-normal-hemispherical reflectance and, hence, normal spectral emissivity for a variety of surfaces. However, the resulting errors are minimal when both the sample and the reference have a similar bidirectional reflectance distribution function (BRDF). In an effort to explore the limits of polarimetry in terms of surface roughness, room temperature measurements on the same samples with various degrees of roughness were performed using both ISR and a laser polarimeter. In this paper the two methods are briefly described and the results of the comparison are discussed.     

红旗轿车三维分离流动特性

介绍了使用激光片光技术及激光多普勒测速仪对红旗ＣＡ７７４ 轿车尾流的三维分离流的尾迹和速度分布测定的试验研究。研究表明,光学流态显示和数字图象技术相结合,可以有效地揭示汽车的尾流结构,诊断阻力来源。本项研究为建立汽车三维分离流动的动态仿真理论模型提供了依据。