基于遥感的湄公河次区域森林地上生物量分析

森林对维护区域生态环境及全球碳平衡、缓解全球气候变化发挥着不可替代的作用,对森林地上生物量进行精确估测能够大大减小陆地生态系统碳储量的不确定性。本文结合机载激光雷达、星载激光雷达和成像光学遥感等数据进行大湄公河次区域的森林地上生物量估测,生成连续的森林地上生物量图。结果表明：①基于星机地协同观测数据可以有效地估测森林地...     

光学限制器的优化与设计

以激发态吸收材料为例,使用有效三能级模型,介绍了浓度梯度分布光限制器和串级光限制器的设计原理和方法.这两种设计方法能有效提高光限制器的动态范围,达到优化设计的目的.     

光互联网的最新进展

本对光互联网领域最新研究热点进行了综述，主要从光互联网的传输技术、激光技术、光交换技术等方面进行了全面的论述．重点从光互联网传输的损耗、光纤色散、光纤的有效面积、最有发展前途的VCSEL激光器、／VIENS光交换等方面进行综述，目的是让从事光互联网研究把握光互联网的最新发展动态，瞄准当前光互联网研究的方向，掌握国际上光互联网的最新进展和热点，有宜于我国光互联网系统的设计、开发与应用。     

一种可用于光抽运共振实验的新泵浦源

本文介绍一种可用于光抽运实验的新泵浦源, 该光源具有高稳定、可调节、可调制和多波长范围等特点; 并介绍该源在原子跃迁谱线观测中的一种应用.     

正交CaTiO3电子结构及光学性质的第一性原理研究

基于密度泛函理论,采用第一性原理投影缀加波方法(PAW),应用广义梯度近似(GGA)处理交换关联能,计算了正交CaTiO3块体材料的晶格参数、电子能带结构、态密度和光学性质。几何优化结果获得的晶格参数和原子坐标与已有的理论和实验数据很吻合。研究表明,正交CaTiO3是带隙为2.43 eV,价带顶和导带底都在Γ点的直接带隙半导体,价带顶和导带底主要由Ti-3d,O-2p态杂化而成。另外,计算了正交CaTiO3的吸收光谱,发现在波长较短的紫外光波段有一强烈吸收峰,基于能带和态密度分析了吸收光谱与电子跃迁间的关系,为正交CaTiO3的应用提供了理论依据。     

GaussView辅助配合物旋光异构教学

结合大学化学教学的实际情况,应用CaussView对配合物的旋光异构现象进行了直观的解释,有利于学生形象地理解其空间结构,增强课堂教学的趣味性,激发学生的兴趣.     

光网络技术的发展

本文阐明了光网络技术的发展及其数字图书馆的作用。     

光时域反射仪测试数据模型研究

文章采用二进样条小波理论对OTDR信号按Mallat算法进行变换，提出了事件点问的局部数学模型以及整个测试数据的整体数学模型，从而为光纤监测数据的自动分析提供了依据。     

《光学测量》教学改革的若干思考

本文在教改指导思想下并结合教学实践,对现行教学模式下《光学测量》课程教学过程中主要存在的问题和解决方案进行了有效的教学改革探讨与尝试。实践证明这些改革措施在缓解授课学时与教学内容的矛盾,强化教学质量,拓宽学生的知识面以及增强学生学习兴趣等各方面效果显著。     

Review of several optical non-destructive analyses of an easel painting. Complementarity and crosschecking of the results

Five optical analyses of a given work of art are presented, using multispectral imaging, optical coherence tomography, goniophometry, UV-fluorescence emission spectroscopy and diffuse reflectance spectroscopy. All these methods are non-destructive, contactless, and implementable in situ. They all lead to results in quasi-real time. The multispectral camera allows imaging of the whole painting with very high definition and recording of 240 millions of spectra. Optical coherence tomography allows local 2D and 3D imaging with in-face and in depth stratigraphies inside the painting with a micrometric accuracy. It allows the evaluation of the pigment volume concentration inside a layer, the measurement of the thickness of one or two varnish layers, the detection and measurements of gaps inside the paint layer, the depth of varnish micro-cracks. Goniophotometry allows the measurement of the upper surface state of the painting in different locations, by quantifying the mean slope of the facets making up the surface. UV-fluorescence emission spectroscopy allows the identification of the resin, the binder and the ageing state of varnishes by use of databases of reference varnishes. Diffuse reflectance spectroscopy leads to pigment, pigment mixture and dye identifications again by use of databases. The three last methods are implemented with the same portable multi-function instrument. It allows time saving, locations on request in front of the artwork and easy use by non-scientists. Each instrument is described with its protocol and accuracy. The studied painting is a portrait of a lady painted by the Austrian artist Franz Strotszberg, chosen for its several restorations. The five kinds of results are successively detailed, analysed and compared between themselves. It is shown that the different results are complementary and their crosschecking brings thorough information. For example, the shape of the network of varnish micro-cracks detected on the surface with the multispectral camera is added to the measurement of their depth with optical coherence tomography. Another example allows connecting two different surface states of the upper varnished surface measured by goniophotometry with the identification of these varnish with UV-fluorescence and with their thicknesses measured with optical coherence tomography.