Investigations regarding the behaviour of historic glass and its surface layers towards different wavelengths applied for laser cleaning

The application of lasers for the removal of superficial deposits from historic stained glass is a comparatively new field of scientific interest. Experimental studies concerning the behaviour of glass substrates and the corresponding superficial deposits towards different laser wavelengths were carried out. The experiments were performed using wavelengths of λ = 193 nm (ArF-Excimer), 308 nm (XeCl-Excimer), 355 nm (Nd:YAG third harmonic) and 1 064 nm (Nd:YAG fundamental) in comparison to λ = 248 nm (KrF-Excimer). This comparison is due to the fact that the present knowledge is based on the 248 nm wavelength. Specially prepared model glass samples representing the original fragments and samples of organic polymers (formerly used as a protective material for historic stained glasses) were used to study the effects of laser radiation and were subsequently characterised by optical microscopy.     

运动后低氧暴露对血液流变学及红细胞形态的影响

研究目的：观察常氧运动后低氧暴露情况下血液流变学及红细胞形态的变化。研究方法：8名受试者以75％ VO2max强度分别完成2次1h蹬功率自行车运动，间隔1周。第1周受试者以75％ VO2max强度蹬功率自行车1h后即进入低氧室内(氧气浓度：15．4％，相当于海拔2500m)休息30min。第2周同一时间，受试者以同等负荷运动1h后常氧环境休息30min。每次实验分别于安静时、运动后即刻、运动后30min采取静脉血5ml，测血液流变学变化和扫描电镜(SEM)下观察红细胞形态变化。结果：运动后血液粘度升高，红细胞变形能力下降，红细胞形态由双凹圆盘状变为单侧凹陷另一侧隆起似礼帽状的I型口形红细胞。结论：运动后低氧暴露不利于血液流变学及红细胞形态的恢复。     

影响雪与滑板摩擦系数的几种因数的研究

介绍了雪与滑板的测量系统和利用单片机对数据采集系统。为了提高实验精度,对光电门进行了改进,大大缩短了电平跳变时间,同时对雪与滑板之间的摩擦系数作了比较系统的实验研究。实验结果为制作雪的模型材料提供了基本依据。     

超快激光脉冲的产生和放大

超快激光脉冲是实现超高速通信最为重要的部分.近十年来,啁啾脉冲放大技术和宽带增益介质的结合,高功率超快激光脉冲取得了迅猛的发展.在小型实验室桌面激光器就可以产生数太瓦功率的激光.本文介绍了用啁啾脉冲放大技术实现超快脉冲的产生和放大.     

Phase Transformations of Graphite and Carbon Black by Laser with Low Power Density

The structure phase transformations of graphite and carbon black induced by pulsed laser were studied in this paper.Under irradiation with laser beam of 1.06 μm wavelength and power density of 106 W·cm-2,both graphite structure and carbon black structure were changed obviously.The results of Raman analyses and Transmission Electron Microscopy(TEM)observations show that graphite transforms into nanodiamond about 5 nm and carbon black is graphitized.It is demonstrated that graphite is the intermediate phase in the transformation from carbon black to diamond,and graphite is easier to transform into diamond by laser irradiation than carbon black.     

单模激光器的量子理论分析

给出了单模激光器的量子理论．针对两能级原子介质，研究激光器的三种工作状态，并将量子理论结果与兰姆的半经典理论结果进行比较．     

探讨英语快速阅读的问题与技巧

信息时代的信息爆炸,学生时代的应试之需,提高快速阅读能力,势在必行。掌握必要的阅读技巧,克服不良的主客观因素,将是提高快速阅读能力的关键。     

基于激光光斑检测的数码相机测距技术

提出了一种基于激光光斑检测的数码相机测距方法,在数码相机上加装一个激光器,使激光光束与相机镜头的光轴平行,对拍摄到的数码相片中的激光光斑进行检测,再根据透镜成像的物像关系实现距离的测量.研究了利用LoG滤波器对激光光斑进行增强的方法,实现了背景灰度值大于光斑灰度值情况下的光斑分割,从而实现激光光斑的位置检测.并进行了实验研究,实验结果表明,采用本文提出的方法实现对物体距离的测量是可行的.     

Searching high gray scale FPD scanning matrix based on PSO

With the increase of gray scale and flat panel display (FPD) size, subspace bitwise scanning strategy can be replaced traditional scanning method to cut down frame frequency. However, the direct searching strategy (DSS) becomes unfeasible to obtain corresponding high gray scale scanning matrix. Thus, particle swarm optimization (PSO) is introduced to accelerate searching for high gray scale weights scanning matrix (WSM) with its parallelism and global optimization feature. Finally a WSM of 256 gray scales is found out successfully with Matlab, which both gray linearity and scanning efficiency are satisfied.     

基于FPGA与MC8051 IP核的可调窄脉冲激光泵浦源的研制

介绍了一种基于FPGA与MC8051IP核的可调窄脉冲激光泵浦系统.该系统主要作为低重复频率光信号的放大器泵浦源.系统采用MOSFET作为功率开关管驱动半导体激光器发出的光脉冲作为激光泵浦源,可驱动大功率的LD,最大驱动功率可达30W.利用高速FPGA芯片（EP2C8）和VHDL语言,设计激光泵浦源的窄脉冲数字控制电路.利用MC8051软IP核实现智能控制,系统输出脉冲周期、脉冲宽度以及脉冲幅度都可调.系统采用多种有效保护措施,性能稳定可靠.