信标光波长对全场补偿的影响

 激光在近水平长距离传输时,闪烁效应会影响自适应光学的校正效果。在Rytov近似下,导出了纯相位补偿方差和全场补偿方差与信标光波长的关系,研究了信标光波长对补偿效果的影响。结果表明,当信标光的波长与主激光波长之比小于1.89时,全场补偿的方差小于纯相位补偿的方差。     

强湍流效应下不同信标波长的自适应光学校正

激光在大气中长距离传输时所产生的相位不连续点的数目与位置不仅与大气湍流和传输距离有关，而且与传输的激光波长有关。由于对主激光进行补偿的相位是从畸变的信标光场中获得的，当畸变光场中出现相位不连续点后，畸变光场的相位由连续相位部分和不连续相位部分组成，不连续相位部分直接与畸变光场中出现的相位不连续点的数密度和其所在的位置有关，一般情况下，主激光的波长与信标光的波长是不同的，因此当主激光的波长一定后，为了对不连续相位进行补偿，以便提高强湍流效应条件下的自适应光学校正能力，必须要考虑合作信标的波长。计算结果表明，考虑了不连续相位的影响后，虽然对主激光的校正效果有所改善，但对不同波长的信标改善的效果并不相同，只有信标光波长稍长于主激光的波长时，校正效果才有明显的改善。     

光波相位不连续点的探测

提出了同时利用哈特曼波前传感器测量的子孔径波前斜率和光强数据进行信标光相位复原的改进算法,并在此基础上对实测的斜率数据进行分析,结果表明在强湍流效应情况下,信标光相位中存在不连续点。     

双变形镜自适应光学全场补偿模拟

在双变形镜自适应光学系统中 ,实现全场补偿的关键步骤之一是使得变形镜 2上主激光的振幅分布具有信标光振幅分布。根据 Y-G波场恢复理论 ,编制了波前恢复程序 ,研究了实现振幅和相位校正湍流问题。研究表明 ,相对于纯相位补偿 ,全场补偿使得 Strehl比提高了 1 .2 7～ 2 .50倍。在变形镜 1和变形镜 2之间的距离为 1 0 m时 ,也使得 Strehl比提高 1 .1 3～ 1 .50倍。     

基于自适应光学技术控制光束近场场强

在双变形镜自适应光学系统中,需要主激光出射时与信标光的振幅分布一致、相位共轭,当主激光到达目标时光波的分布与目标上发射的信标光光波分布相同,主激光的振幅和相位都得到校正。根据双变形镜自适应光学技术的概念,提出一种基于自适应光学技术控制光束近场场强的方法,从而实验验证双变形镜技术的可行性。该方法利用哈特曼传感器探测到的波前信息,对变形镜进行控制,实现了对光束近场场强的控制。仿真结果表明该系统对光束近场强度能进行较好地校正,使校正前后光束振幅的残余均方差值从0.310 0降为0.052 2,同时实验也验证了这种方法的可行性。     

人造信标自适应光学系统中的非等晕性

推导了人造信标自适应光学系统对激光大气传输湍流效应进行位相补偿时信标光与主激光间的剩余位相结构函数，讨论了人造信标自适应光学系统中的非等晕性—聚焦非等晕性。     

量子光通信中偏振光空间姿态传递

通过设计正交偏振光信标器,实现了空间信标姿态的单光路传递,为星地量子光链路的建立提供了条件.通过分析光学器件,尤其是镀膜器件中偏振信标光的传递特性,仿真分析不同入射角、旋转角条件下,出射信标光的偏振模式.分析了由光学器件引入的位相差和不同反射率、透射率对偏振模式的影响.利用琼斯矩阵推导了马吕斯定律在椭圆偏振光入射时的表达形式,建立起测量椭圆偏振光主偏振方位角模型.利用光电位置传感器接收正交信标光,结合光电位置传感器的光点位置检测能力解耦信标光的俯仰角和方位角,利用光电位置传感器的光强探测能力解耦信标光的偏振基矢角,实现了单器件三维信标姿态测量.实验表明,所述系统具有完成信标光三维姿态检测的能力,可用于星地量子光通信、空间信标姿态检测.     

光束定向器中膜厚不均匀性对远场性能的影响

讨论DF(氟化氘)强激光系统光束定向器中的光学薄膜，用偏振光线追迹分析定向器出瞳主激光、信标光偏振态变化，计算膜厚不均匀性对远场性能的影响．     

三硼酸锂晶体Ⅰ类非临界相位匹配下近红外波段的差频产生

利用差频发生器产生波长范围为1.1~2.2μm的可调谐近红外激光.实验搭建了差频光路系统,以0.56~0.71μm染料激光器作为泵浦光、1.064μm的半导体激光器作为信号光,经过三硼酸锂晶体在Ⅰ类相位匹配方式条件下通过温度调谐非临界相位匹配方式差频产生较高功率的近红外激光,在近红外波段测得其平均输出功率在30mW以上.泵浦光功率为1.2 W、信号光功率为0.31 W时,测得差频波长为1.54μm的输出功率为35mW,转化效率达11.7%.该近红外差频发生器具有宽调谐、窄线宽的特点.     

非谐振腔型KTP光参变振荡器

研究了双晶体走离补偿、非谐振腔型KTP光参变振荡器，利用一套膜片实现了KTP相位匹配所允许的全波段调谐，信号光调谐范围0.698μm-1.026μm，闲频光调谐范围1.105μm-2.237μm。5倍阈值处，信号光840nm最高输出能量53mJ，能量转换效率25.8%，量子转换效率40％，闲频光的量子郊率也达到32％。     

Study of thermo-optical distortions in a plate active element with zigzag beam path

Phase distortions introduced into the laser beam propagating in a plate under diode pumping of the active element (AE) and for intentionally caused temperature gradients in the AE are studied. The temperature distribution along the optical axis of the active element is measured during its end diode pumping. Phase distortions of the test beam propagating through the nonuniformly heated active element are studied. Interference patterns are obtained and optical distortions of the test beam are measured at various temperature gradients in the crystal.     

光纤通信用的发光管非线性P-I特性分析研究

本文综合分析了作者从制造光纤通信用的GaAs-GaAlAs发光二极管(LED)到应用这些LED制作端机系统所遇到的P-I非线性特性。文中深入地讨论了P-I非线性特性产生的原因及它对光信号失真的影响,并提出了解决办法。     

高功率激光器腔镜热变形对输出光束质量的影响

利用有限元分析法结合Fox-Li迭代法,考虑腔内本征模式与腔镜热形变的相互耦合作用,计算模拟了正支共焦非稳腔的本征模式分布,定量分析了高功率激光器腔镜热变形对输出光束质量的影响,重点讨论了腔镜热变形所引起的腔内本征模式相位特性的变化,并从波前功率谱密度、Zernike像差系数及光束质量值等角度对腔镜发生热形变前后的激光器输出光束的光束特性进行比较分析。研究结果表明:高功率激光器腔镜热形变对输出光束的光束质量会产生一定的影响,且随着激光输出功率的增大,镜面热形变引起的输出光束波前相位高频比例及Zernike高阶像差均会有所增大,波前畸变程度也明显变大,光束质量逐渐变差。     

计及风和湍流的热晕及其相位补偿的数值研究

本工作用包括热晕、湍流和风等效应的等压近似下四维激光传输程序，数值计算了激光大气传输中的整束热畸变效应及其理想相位补偿，得到了各种情况下的激光大气传输畸变图象，并分析了热晕和湍流的相互作用。另外，还讨论了时、空步长的选取原则。     

A simple quadrupole-octupole electromagnetic lens

Charged particle beam trajectories in a simple electromagnetic quadrupole-octupole lens are numerically calculated based on analytical expressions for the +potential distribution. Locations of the lens foci in the image space are determined over a wide range of initial conditions. Relationships between the electrostatic and magnetic lens components that provide correction for chromatic aberrations of off-axis beams, which are different from classical beams, are obtained. Phase contours at the lens exit are calculated for beams occupying the major part of the aperture, and conditions for transforming the phase contour with minimal distortions are found.     

(e,2e)电子动量谱仪研制和若干原子分子的电子动量谱测量

研制成功了一台先进的多功能用途的（e，2e）电子动量谱仪．装置采用电子束和气体束交叉碰撞方式；使用微通道板一维位置灵敏电子探测器；成功地实现了多参数数据获取和离线分析技术．利用该谱仪分别测量了氦、氩原子和氢、甲烷分子的电离能谱和电子动量谱．该谱仪的能量分辨率为ΔE=1.8eV，动量分辨率为Δp～0.15au 关键词：     

Specific heat,cell parameters,phase T - p diagram,and permittivity of cryolite (NH 4 ) 3 Nb(O 2 ) 2 F 4

The temperature dependences of the specific heat, unit cell parameters, susceptibility to hydrostatic pressure, and permittivity of cryolite (NH₄)₃Nb(O₂)₂F₄ have been studied. Phase transitions of nonferroelectric nature have been detected. Entropy parameters point to the relation of structure distortions to ordering processes.     

相对论性带电粒子束在轴对称电场和磁场中的温度和能量展宽

从单粒子的相对论性运动方程出发,首先解出运动常数,然后用这些运动常数构成符合Vlasov方程的束粒子分布函数,再由该分布函数算出轴对称电场和磁场中相对论性带电粒子束的束温度和能量展宽,并且对弱相对论性情况和强相对论性情况作了讨论。 关键词：     

Mode shapes analysis of a cracked beam and its application for crack detection

In this paper, mode shapes of a cracked beam with a rectangular cross section beam are analysed using finite element method. The 3D beam element is applied for this finite element analysis. The influence of the coupling mechanism between horizontal bending and vertical bending vibrations due to the crack on the mode shapes is investigated. Due to the coupling mechanism the mode shapes of a beam change from plane curves to space curves. Thus, the existence of the crack can be detected based on the mode shapes: when the mode shapes are space curves there is a crack in the beam. Also, when there is a crack, the mode shapes have distortions or sharp changes at the crack position. Thus, the position of the crack can be determined as a position at which the mode shapes exhibit such distortions or sharp changes. While in previous studies using 2D beam element, distortions in the mode shapes caused by a small crack could not be detected, these distortions in the case using the 3D beam element can be amplified and inspected clearly by using the projections of the mode shapes on appropriate planes. The quantitative analysis is also implemented to relate the size and position of the crack with the observed coupled modes. These results can be applied for crack detection of a beam. In this paper, the stiffness matrix of a cracked element obtained from fracture mechanics is presented and numerical simulations of three case studies are provided.     

Laser beam induced optical aberrations in phosphate and fluoride phosphate glasses

Designing pulsed laser amplifiers requires detailed knowledge about beam distortions at the amplifying medium. Time resolved experiments have been performed on fluoride phosphate and pure phosphate glass in order to study optical aberrations induced by pump beam irradiation. By means of a probe beam tunable in wavelength, it was possible to discriminate between thermally induced variations of the optical path and beam narrowing effects due to the radial gain distribution. The experimental results were analyzed theoretically regarding Fresnel diffraction. A quite different response was found for the two types of glass despite their similar nominative properties. PACS 42.60.Jf; 42.60.By; 42.15.Fr