现代高分辨拉曼光谱仪的配置及应用研究

拉曼光谱分辨率是关系到从光谱中提取出样品结构信息的关键参数,高分辨拉曼光谱能够提供更多、更精细的样品有关信息。在此全面分析了现代高分辨拉曼光谱仪中决定光谱分辨率的各参数,辨析了易于混淆的分辨率和色散度概念。用理论分析和实验结果说明光栅密度与光谱分辨率的关系以及采用高密度光栅增进光谱分辨率所受到的限制、如何利用长焦长光栅增进光谱分辨率而不损害仪器通光效率、入射狭缝宽度对光谱分辨率及灵敏度的影响,在此基础上如何求得一个合理的平衡选择;并且用不同配置的现代新型拉曼光谱仪实验研究了多层硅结构中的应力分布和单壁碳纳米管管径分布,实验结果清晰地佐证了以上分析,并充分说明了拉曼光谱测量中选择分辨率的重要性。     

On metallic gratings coated conformally with isotropic negative-phase-velocity materials

Application of the differential method (also called the C method) to plane-wave diffraction by a perfectly conducting, sinusoidally corrugated metallic grating coated with a linear, homogeneous, isotropic, lossless dielectric-magnetic material shows that coating materials with negative index of refraction may deliver enhanced maximum nonspecular reflection efficiencies in comparison to coating materials with positive index of refraction.     

Growth Modeling of Fiber Gratings: A Numerical Investigation

We have developed a simple method to analyze the growth process of fiber gratings (FGs) in the core of photorefractive optical fibers. It is based on the exponential saturation model and it takes into account the type of photosensitive fiber used, the exposure times, and the incident optical power. The photorefractive fiber has been characterized by two parameters: the saturation photoinduced refractive index change and the saturation energy, which can be obtained experimentally. We carry out a numerical investigation for the growth process of a uniform FG. The experimentally observed phenomena of shifting the Bragg optical frequency with exposure times and the appearance of higher-order Bragg resonances are predicted and discussed.     

Coupling efficiency in grating tuned carbon dioxide waveguide lasers

The coupling efficiency in typical CO₂ waveguide lasers when the feedback element is a diffraction grating is investigated theoretically. A scalar diffraction integral approach is adopted, and the laser is assumed to operate on its lowest loss waveguide mode.     

基于倾斜场镜的C-T成像光谱仪优化设计

残留谱线弯曲限制了切尔尼-特纳平面光栅光谱仪在成像光谱仪中的应用.本文不同于传统的基于棱镜的光栅谱线弯曲补偿方法,提出了基于倾斜场镜的补偿方法,即在校正场曲的同时对入射到场镜不同区域,不同波长的狭缝像分别进行谱线弯曲校正,且没有改变系统的其它光学特性.对狭缝大小为7.8mm×0.016mm、光谱范围0.31~0.5μm、光谱分辨率0.4nm、物方焦距70mm、1∶1放大倍率的切尔尼-特纳成像光谱仪进行了优化设计,结果全谱段、全视场MTF0.8,点列图RMS半径小于9μm,相对谱线弯曲小于0.2%,满足设计要求.实际设计表明该方法对于可选用光学玻璃有限,且能量较弱的紫外光学系统是一种可选的优化设计方法.     

A five-channel grating spectrometer for millimeter waves

A five-channel grating spectrometer for use in millimeter wave band (25100GHz) is described with its design theory of optical path, and measured results of insertion loss and resolving power.     

平面变线距光栅（VLS）的基本原理与线距修正系数的检测

变线距光栅是一种自消部分象差的光学元件,本文提出了用激光束检测变线距系数的理论模型,计算表明变线距光栅的衍射波与平面波的干涉条纹可以用于检测变线距系数。     

计算机数据库技术在二米光栅摄谱仪检定项目中的开发应用

利用先进的计算机数据库VisualFoxpro6.0技术,处理二米光栅摄谱仪检定《国家级标准样品考核》这一检定项目,使原来复杂的仪器检定工作变得快速、准确、简便,在一定程度上提高了仪器检定的工作效率。     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.