小孔眼镜的波动光学原理

解释小孔眼镜对近视眼和远视眼都有助视作用的原理,讨论小孔眼镜的制作工艺。     

眼睛与光学

眼睛是我们每个人都具有的“光学仪器” ,了解眼睛的构造和性能对于我们正确用眼和保护眼睛是十分必要的 .1　人眼的构造人眼外表形状为球形 ,直径约为 2 5ｍｍ ,外部有一层白色不透明坚韧的巩膜 ,就是平常所说的“白眼珠” .巩膜的正前方是一无色的透明角膜 ,角膜的后面为眼睛     

Near Infrared Broadband Emission from Bismuth-Dysprosium Codoped Chalcohalide Glasses

We investigate the broadband infrared emission of bismuth doped and bismuth/dysprosium codoped chalcohalide glasses. It is found that the bismuth/dysprosium codoping can drastically enhance the f/uorescence as compared with either bismuth or dysprosium doped glasses. Meanwhile, the full width at half maximum of bismuth/dysprosium codoped glasses is over 170 nm, which is the largest value among all the reported rare-earth doped chalcohalide g/asses. An ideal way for energy consumption between bismuth and dysprosium ions is supposed. Such improved gain spectra of both bismuth and dysprosium ions may have potential applications in developing broadband fibre amplifiers.     

小圆孔的正负焦距与小孔眼镜

提出了证明小圆孔具有正,负焦距的一种方法,简要地介绍子关于小孔眼镜的实验研究。     

Large and Ultrafast Third-Order Nonlinear Optical Properties of Ge-S Based Chalcogenide Glasses

We report ultrafast third-order nonlinear optical （NLO） properties of several chalcogenide glasses GeSx （x = 1.8, 2.0, 2.5） measured by femtosecond time-resolved optical Kerr gate technique at 82Ohm. The third-order nonlinear susceptibility of GeS1.8 glass is determined to be as large as 1.41 ×10^-12 esu, which is the maximum value of the third order nonlinear susceptibility Х^（3） for the three compositions investigated. The symmetric Gauss profiles of optical Kerr signals reveal the nature of ultrafast nonlinear response of these samples, which are originated from the ultrafast polarization of the electron clouds. By detailed microstructural analysis of these glasses based on the chain-crossing model （CCM） and the random-covalent-network model （RCNM）, it can be concluded that Х^（3） value of GeSx glasses can be enhanced greatly by S-S covalent bonds or S3 Ge-GeS3 ethane-l＆e units.     

Raman and optical absorption spectroscopic investigation of Yb-Er codoped phosphate glasses containing SiO_2

Yb-Er codoped Na2O-Al2O3-P2O5-xSiO2 glasses containing 0 - 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between pS＋ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4＋, most probably there coexist [SiO4] tetrahedron and [SiO6] oetahedron in our glasses. Within the range of 0 - 20 mol% SiO2 addition, the stimulated emission cross-section of Era＋ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3＋, Ω2 does not change greatly, but Ω4 and Ω6 decrease obviously with increasing SiO2 addition, because the bond between Er3＋ and O2- is more strongly eovalently bonded.     

Effects of Yb^3＋ in Er^3＋/Yb^3＋ Codoped Fluorophosphate Glasses

For the Er^3＋ /Yb^3＋ codoped fluorophosphate glasses, Judd-Ofelt theory is used to analyse the influence of YbF3 as not a sensitizer but an average component on the spectroscopic properties around 1530nm emission. The double roles of Yb^3＋, as a sensitizer and as an average component, are discussed. It is found that Yb^3＋ as an average component contributes to the increase of fluorescence lifetime, and Yb^3＋ as a sensitizer has the best sensitization when its concentration is 2.4 mol%.     

Design of apochromatic telescope without anomalous dispersion glasses

A novel lens system with correction of secondary spectrum without using anomalous glasses is presented. The lens system comprises four separated lens components, with three of them being subapertures. Two examples of apochromatic telescope are presented, both with the use of typical normal glasses, namely crown K9 and flint F5 glasses, and low-cost slightly anomalous dispersion glasses. Secondary spectrum and other chromatic aberrations of the two design examples are corrected.     

盲人导航眼镜的研究

现代社会高楼林立、交通发达,对于盲人来说,到处都有障碍物,这给他们的出行带来了诸多不便,盲人出行安全也逐渐成为人们关注的焦点.本导航眼镜就是以辅助盲人出行为目的,通过在眼镜上设计两套超声波测距系统来解决帮助盲人及时避开障碍物.将超声波测量得到的数据进行相关的算法处理,能够得到障碍物距离、速度、方位三方面的信息,以左右振动的形式告知盲人,从而达到给盲人导航的效果.眼镜结构简单,操作方便,具有集成度高,准确性好,低功耗,低成本等特点,市场前景广阔.     

Broadband Infrared Luminescence from Bismuth-Doped GeS2--Ga2S3 Chalcogenide Glasses

Near-infrared luminescence is observed from bismuth-doped GeS2-Ga2Sa chalcogenide glasses excited by an 808 nm laser diode. The emission peak with a maximum at about 1260 nm is observed in 80GeS2-2OGa2 Sa：O.fBi glass and it shifts toward the long wavelength with the addition of Bi gradually. The full width of half maximum （FWHM） is about 200 nm. The broadband infrared luminescence of Bi-doped GeS2-Ga2Sa chalcogenide glasses may be predominantly originated from the low valence state of Bi, such as Bi＋. Raman scattering is also conducted to claxify the structure of glasses. These Bi-doped GeS2 Ga2Sa chalcogenide glasses can be applied potentially in novel broadband optical fibre amplifiers and broadly tunable laser in optical communication system.