准分形光子晶体多频带隙的特性及其应用

用时域有限差分方法计算了多种准分形结构光子晶体的能带. 数值计算结果表明, 这些结构的光子晶体存在多频带隙的特点, 且带隙的宽度及中心频率以及带隙中导带的中心频率均随准分形光子晶体单胞内结构单元几何形状的改变而改变.     

小型方波脉冲磁场装置的研制

完成了小型方波脉冲磁场装置的双线圈负载设计,在一定区域内获得了近似匀强磁场。采用阻抗2 的6级脉冲形成网络作为初级储能和脉冲形成单元,对匹配电阻放电产生了方波脉冲电流波形。研制了一种场畸变气体火花间隙作为主放电开关,有效减小了装置的动作时延和分散性。实验结果表明:负载中心峰值磁感应强度达到0.04 T,方波磁场平顶时间约3 s,平顶度小于5％,上升前沿（磁感应强度峰值10％～90％）小于0.5s,装置的动作时延抖动小于10 ns（标准偏差）。     

剑麻织物增强乙烯乙酯基复合材料的剩余强度研究

采用中间开孔试样对剑麻织物增强乙烯乙酯基复合材料的剩余强度进行了研究．两种化学处理剂硅烷和高锰酸钾分别被用来对纤维表面进行处理,并对处理前后该种复合材料的剩余强度的变化进行分析,同时,利用微观分析揭示了剑麻织物增强乙烯乙酯基复合材料的剩余强度与破坏形貌之间的关系．     

The research of used in aircraft optical windows sensor systems

The optical windows used in aircrafts protect their imaging sensors from environmental effects. Considering the imaging performance, flat surfaces are traditionally used in the design of optical windows. For aircrafts operating at high speeds, the optical windows should be relatively aerodynamic, but a flat optical window may introduce unacceptably high drag to the airframes. The linear scanning infrared sensors used in aircrafts with, respectively, a flat window, a spherical window and a toric window in front of the aircraft sensors are designed and compared. Simulation results show that the optical design using a toric surface has the integrated advantages of field of regard, aerodynamic drag, narcissus effect, and imaging performance, so the optical window with a toric surface is demonstrated to be suited for this application.     

“黄金”圆锥曲线的又一充要条件

<正>本文的圆锥曲线是就椭圆和双曲线而言.性质1椭圆(x~2)/(a~2)+(b~2)/(y~2)=1(a>b>0)是黄金椭圆的一个充要条件是:该椭圆的四个顶点所确定的菱形的内切圆过椭圆的焦点.     

Optical Feedback Characteristics in He-Ne Dual Frequency Lasers

Optical feedback characteristics in He-Ne dual frequency lasers are studied systematically in different feedback power ratios with a variable attenuator. Feedback power ratios vary from 0.010 up to 0.998. Five distinct regimes of self-interference effects are found and defined as regimes Ⅰ, Ⅱ,Ⅲ,Ⅳand Ⅴ. Accordingly, five optical feedback levels have been put forward in He-Ne dual frequency lasers. Strong mode competitions are observed in regimes Ⅲ and Ⅳ. In regime Ⅴ, multiple feedback effects are investigated. The basic theoretical analysis is also presented. Our results can advance the research of self-mixing interferometer and displacement sensor of He-Ne orthogonally polarized dual frequency lasers.     

加速溶剂提取-液相色谱-原子荧光光谱法测定对虾饲料中5种形态的汞

称取经粉碎的样品1.000 0g,置于加速溶剂提取池中,加入10mL的5mol·L-1盐酸溶液、1mL的5mol·L-1氯化钾溶液和2mL的10mol·L-1半胱氨酸溶液;在8.0MPa和70℃下,预加热2min,加热5 min,静态提取5min,分离,重复上述提取过程2次,合并提取液;加入0.2mL的0.5mol·L-1半胱氨酸溶液、1.5mL的6mol·L-1氢氧化钠溶液,以10 000r·min-1离心5min,将上清液氮吹浓缩并用硝酸(5+95)溶液定容至1mL,过0.45μm尼龙滤膜后,采用Eclipse XDB-C18反相色谱柱(150mm×4.6mm,5.0μm)分离溶液中的甲基汞、乙基汞、无机汞、硫柳汞和苯基汞,流动相为50g·L-1乙腈溶液+5g·L-1乙酸铵溶液+1g·L-1半胱氨酸溶液(体积比为1∶1∶1),用原子荧光光谱仪进行测定。5种形态的汞的质量浓度在一定范围内与其荧光强度呈线性关系,测定下限(10S/N)在1.0~2.5μg·kg-1之间。加标回收率在91.0%~98.3%之间,测定值的相对标准偏差(n=6)在0.94%~2.7%之间。     

A Novel Tunable Dual-frequency Laser with Large Frequency Difference

This paper proposed a novel tunable dual frequency laser with large frequency difference,which used LD to pump the Nd∶YAG microchip in the end surface and put the liquid pressure on the radial direction of the crystal by a pressure-transporting thin film. As a result of the stress birefringence, there was a mode splitting phenomenon of the microchip laser longitudinal mode. Both theoretical analysis and experiments indicated that there is a directly proportional relation between the frequency difference and the pressure, so the tunable frequency difference could be obtained when the pressure was changed. A large frequency difference of about 3.4 GHz with linear tunable relation was achieved in the experiment,so it can be a practical light source for the absolute distance interferometry.     

Laser Micro-beam Manipulation System for Cells

This paper introduces a laser micro-beam system for cells manipulation. The laser micro-beam system comprises a laser scissors and a laser tweezers, which are focused by a Nd∶YAG laser and a He-Ne laser through a microscope objective, respectively. Not only the overall design of the laser micro-beam system is discussed, but also the design and choice of the critical components. A laser micro-beam system was constructed and anticipated experiment results were gained. Yeast cells can be successfully manipulated with the laser tweezers. Chromosomes can be successfully incised with the laser scissors.     

几种新型LD泵浦Nd∶YAG双频激光器

介绍了几种LD泵浦Nd∶YAG双频激光器 ,均应用双折射原理实现。一类是利用自然双折射效应 ,在激光谐振腔内加入自然双折射元件 ;另一类则是对YAG晶片加压力 ,使YAG晶片本身成为应力双折射元件。由于双折射效应使激光在谐振腔内产生偏振方向互相垂直的寻常光 (o光 )和非寻常光 (e光 )两种成分。因为o光和e光在双折射元件中有着不同的折射率 ,因此一个激光谐振腔变成了具有两个物理长度的谐振腔 ,从而产生双频激光。改变自然双折射元件或对YAG晶片施加的压力 ,可调谐频差。实验中获得 10 9Hz量级的大频差 ,合成波长可到几十毫米 ,适用于绝对距离干涉测量