解析求解光纤中非稳定扰动的实部和虚部

 对线性化后的非线性薛定谔方程进行了求解，导出了光纤中传输的扰动场复振幅的实部和虚部的解析解。这些普适的表达式表明：在传输距离不太长的初期阶段，扰动的虚部和实部以及幅角的演化都对输入条件十分敏感；在传输距离趋于无穷大时扰动电场增益系数趋于渐近值；波数在初始阶段随传输距离变化，只有当传输距离足够大时才趋于一个常数。     

光散射和消光能量对气溶胶折射系数的敏感性分析

利用米氏理论，对满足不同Ｊｕｎｇｅ谱型气溶胶的后向散射、消光以及两者之比对其折射系数实部和虚部的敏感性进行了数值计算，得出了有益的结论。     

原子吸收限附近完整晶体内的能流方向

研究了原子吸收限附近对称劳厄和布拉格情况下完整晶体内的能流方向．发现在对称劳厄情况下，只有当原子散射因子的虚部对衍射的贡献可以与实部的贡献相比较时，晶体内与色散面上某一结点相对应的能流会偏离色散面的实部的法向；而在对称布拉格情况下，即使在原子散射因子的虚部对衍射的贡献可以忽略时，在所谓的“全反射”区内也会偏离．当衍射仅由原子的虚部引起时，这种偏离在对称劳厄情况下最大，而在对称布拉格情况下最小． 关键词：     

外加电场作用下碳纳米管结构稳定性及结构修饰研究

利用外加电场的方法，对多壁碳纳米管的结构稳定性进行了研究.结果表明当场强达到30 V/nm时，碳纳米管端部的结构失稳，端部碳原子间的π键被打开，外部原子开始进入到碳纳米管的结构中.利用电子显微镜作为纳米加工仪器，通过外加电场的方法在多壁碳纳米管的端部制备了非晶态碳纳米线，形成碳纳米管-纳米线复合结构.碳纳米管和纳米线结合处的σ键作为绝缘界面，形成了电子输运的势垒.     

实虚部关联的量子噪声和泵噪声对单模激光动力学性质的影响

采用具有实虚部关联的量子噪声和泵噪声驱动的单模激光损失模型，用线性化近似方法研究了反映激光动力学性质的光强关联函数，讨论了光强关联函数随时间的演化；并对线性化近似方法的适用范围进行了详细分析，分别讨论了量子噪声强度、泵噪声强度、量子噪声实虚部关联系数对光强相对涨落的影响，得出在小噪声、远离阈值时，线性化近似方法适用范围扩大；小噪声、远离阈值且当量子噪声实虚部无关联时，线性化近似方法适用范围最大的结论. 关键词： 单模激光 光强关联函数 光强相对涨落     

基于Kirkpatrick-Baez显微镜的芯部自发光成像诊断不确定度评估

具备高分辨能力（约5μm）的Kirkpatrick-Baez(KB)显微镜大幅提升了芯部自发光诊断图像的空间分辨率，准确评估诊断不确定度有利于开展内爆对称性调谐，提高内爆性能。建立了针对KB显微镜的在线不确定度评估方法，详细分析了其在线背光照相实验中的图像分辨率和噪声，并对内爆物理实验中的芯部自发光数据进行了不确定度评估。结果显示，芯部自发光P2不确定度为6%,P4不对称性的不确定度为8%，满足了现阶段内爆物理实验的诊断需求。     

氢同位素组合靶丸消融率的同位素修正

国际热核聚变堆(ITER)的芯部加料问题是非常困难的。必须找到某些新的改善芯部加料的机制和新的靶丸注入方式。我们研究了5种氢同位素组合的固态靶丸H2，HD，D2，DT，T2在聚变等离子体中消融过程的同位素修正机制。Parks等人研究了高场侧注入的靶丸消融物质在托卡马克中由于VE产生的径向位移。我们用他们的模型对ITER设计参数作了数值计算。结果表明ITER芯部加料的困难问题有了转机。我们将在另一篇文章中讨论。本文主要介绍5种氢同位素组合固态靶丸消融率的同位素修正对芯部加料效率的影响。     

大气气溶胶粒子数密度谱和折射率虚部的测量

介绍一种综合利用光学粒子计数器和能见度仪测量大气气溶胶折射率虚部的新方法。首先，使用光学粒子计数器测量出大气气溶胶粒子的数密度谱(待订正)，用能见度仪同步测量出水平能见度。然后，根据球形粒子的米氏(Mie)散射理论，通过分析气溶胶粒子的折射率虚部、分档半径、粒子数密度谱、消光系数和能见度之间的关系，对分档半径进行订正，得到折射率虚部和能见度之间的对应关系。结合同步测量的能见度，反演出大气气溶胶粒子的折射率虚部。最后，利用折射率虚部对光学粒子计数器数据进行订正，得到大气气溶胶粒子的数密度谱。     

短脉冲高斯光束的时空形式

考虑到腔模光腰尺寸的频率依赖性，得到了一短脉冲高斯光束在自由空间传播的时域解析形式，发现其可由一复时间变量来描述，复时间变量的实部给出了脉冲的传输时间，其与波前曲率有关，虚部给出了空间量值，两者的交叉项称为时空耦合，并对傅里叶变换极限脉冲和啁啾脉冲的时空形式作了分析。     

基于Rytov积分近似的有限口径定量反演成像（特邀）

提出一种适用于有限口径下高相对介电常数和大尺寸目标物体的反演方法。首先分析了低损耗介质的复折射率，通过有效折射率的计算方法得到有效折射率与介电常数关系；利用高频近似估计对比度函数，通过近似估计散射体内部散射场及其梯度对传统Rytov近似进行数学上的修正，产生无相位条件下Rytov积分近似模型，该模型可以实现定量重建高相对介电常数和大尺寸未知目标的对比度虚部。仿真结果显示有限口径下的Rytov积分近似可以对高介电常数和大尺寸目标的对比度虚部提供精确的形状重建。     

Identification of aerosol species using polarization lidar

This paper presents a new approach that has been developed to identify individual aerosol species using polarization lidar measurements. Individual aerosols can be identified based on their distinct ratios of extinction to backscatter, which are related to the depolarization ratio profile. Aerosol backscatter coefficients can be obtained from these ratios. Differential aerosol backscatter coefficients are proportional to the variation of the ratio of extinction to backscatter coefficient, and the coefficients increase, reach a peak value, and then decrease again, with increasing range.     

Raman Lidar Measurements of Aerosol and Cloud Optical Properties in the Troposphere

A Raman lidar has been developed with photon counting technique. Aerosol and cloud extinction coefficients are derived by nitrogen (N2) molecular Raman scatter returns in the troposphere. Both backscatter coefficients and extinction-backscatter-ratios of aerosol and cloud are presented by simultaneously combining N2 Raman and Mie-Rayleigh returns of aerosol and molecule. Ratios of extinction to backscatter between 20 sr and 70 sr are usually found for aerosol, but less than 15 sr for mid-high altitude cloud in the troposphere.     

Raman Lidar Measurements of Aerosol and Cloud Optical Properties in the Troposphere

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Measurements for profiles of aerosol extinction coefficient,backscatter coefficient,and lidar ratio over Wuhan in China with Raman/Mie lidar

<正>The profiles of aerosol extinction,backscatter coefficient,and lidar ratio in the lower troposphere over Wuhan are measured by a multi-channel Raman/Mie lidar.Using the lidar ratio retrieved by Raman scattering principle,the profiles of aerosol extinction and backscatter coefficients are also retrieved by Mie scattering signals,without a prior assumption about their relation in the traditional pure Mie signals data analyses.The observations by both Raman and Mie are in good agreement with each other.The high coherence shows that the system is reliable,and the Mie and Raman channels are in good adjustment and have the same field of view.     

Mie散射激光雷达研究大气边界层特性

基于Mie散射大气激光雷达,应用Klett算法对回波信号进行了反演,得到大气消光系数和后向散射系数。然后,通过对大气后向散射系数曲线进行拟合得到大气边界层混合层高度以及卷夹层厚度等特征参数。对比雷达实测数据与探空气球所测数据,证明二者存在较好相关性。基于实测数据讨论了四川盆地大气边界层特性对气候的影响。     

双扫描激光雷达精细探测低层大气气溶胶方法

为实现水平非均匀分布的低层大气气溶胶光学特性的遥感探测,提出一种基于双扫描激光雷达的气溶胶精细探测方法.该方法以扫描激光雷达为遥感探测工具,通过双激光雷达相向交叉扫描工作模式,实现对同一空域近地表气溶胶全视野剖面的交叉探测,从而提供双激光雷达方程组以精确求解气溶胶消光和后向散射系数.在数据反演过程中,通过对交叉扫描区域进行坐标化和网格化处理、网格像素单元的初值预设,以及双扫描激光雷达方程组的数值逼近反演得到气溶胶消光.利用长距离扫描激光雷达的数据对该方法进行验证,结果表明,该方法与多角度方法反演所得到的结果随高度变化的趋势具有高度的一致性;同时双扫描激光雷达可提供交叉扫描区域剖面的气溶胶浓度分布,相比于单条廓线具有较大的优势.     

Lidar calibration experiments

A series of atmospheric aerosol diffusion experiments combined with lidar detection was conducted to evaluate and calibrate an existing retrieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost) identical mini-lidar systems for aerosol cloud detection to test the reproducibility and uncertainty of lidars. Lidar data were obtained from both single-ended and double-ended lidar configurations. A backstop was introduced in one of the experiments and a new method was developed where information obtained from the backstop can be used in the inversion algorithm. Independent in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including measurements from both sides of a plume. The correspondence with in-situ measurements is excellent. Finally, the new backstop method is able to reveal information which can close the lidar equation by obtaining the relation between backscatter and extinction in an aerosol cloud. Received: 21 December 1995 / Revised version: 25 July 1996     

Combined raman elastic-backscatter LIDAR for vertical profiling of moisture,aerosol extinction,backscatter, and LIDAR ratio

A combined Raman elastic-backscatter lidar has been developed. A XeCl excimer laser is used as the radiation source. Inelastic Raman backscatter signals are spectrally separated from the elastic signal with a filter or grating polychromator. Raman channels can be chosen to register signals from CO₂, O₂, N₂, and H₂O. Algorithms for the calculation of the water-vapor mixing ratio from the Raman signals and the particle extinction and backscatter coefficients from both elastic and inelastic backscatter signals are given. Nighttime measurements of the vertical humidity distribution up to the tropopause and of particle extinction, backscatter, and lidar ratio profiles in the boundary layer, in high-altitude water and ice clouds, and in the stratospheric aerosol layer are presented. Daytime boundary-layer measurements of moisture and particle extinction are made possible by the improved daylight suppression of the grating polychromator. Test measurements of the CO₂ mixing ratio indicate the problems for the Raman lidar technique in monitoring other trace gases than water vapor.     

New dust aerosol identification method for spaceborne lidar measurements

Classification is a critical step in the backscatter lidar data processing to accurately retrieve extinction and backscatter profiles of atmospheric aerosols and clouds. Different schemes, such as the probability distribution functions (PDFs) method, have been used in the cloud and aerosol classification. In this paper, we attempt to use the support vector machine (SVM) to discriminate aerosols from clouds, with a focus on dust aerosol classification in China. To demonstrate the feasibility of the SVM classifier, we chose dust storms that occurred in the Gobi and Taklimakan deserts and observed by the CALIPSO lidar in spring time 2007. The results show that the SVM can correctly identify the dust storms.     

利用转动拉曼测量大气气溶胶后项散射比

利用大气的弹性散射信号与整个转动拉曼信号的比值,不需要假设任何的气溶胶的消光与后项散射比值,就可得到大气气溶胶的后项散射比。通常测量部分转动拉曼谱线之和代替全部转动拉曼谱线之和。全部的转动拉曼谱线之和是不依赖温度,但部分的转动拉曼谱线之和却是与温度有关的。因此,利用转动部分拉曼谱线之和反演大气气溶胶的后项散射比就会带来误差。模拟了随温度变化不同转动量子数的拉曼谱线之和,并且计算了由这些不同转动拉曼谱线之和反演大气气溶胶后项散射比的误差。然后文章提出了一种新的方法,不需要测量整个转动拉曼谱线之和,而只需要测量单条转动拉曼谱线及大气温度,就可以获得大气气溶胶的后项散射比。最后通过实验给出了实际测量的大气气溶胶的后项散射比的结果。