运用简单物理方法检测自己所戴近视镜

很多同学都戴近视眼镜,但自己所戴眼镜是否合格呢?我们可以用简单的物理方法判定眼镜是否适合自己的眼睛,是否符合国家的眼镜标准.     

基于光路回归方法研究潜水近视眼镜度数

为了确认在水下潜水近视眼镜度数是否发生改变,依据光路回归方法对水下传播光路进行分析.同时利用分光计装置的目镜成像代替人眼,使得近视程度在其中得到清晰呈现,从而开展相关实验研究.结果表明,在水下深度较浅时,潜水镜度数几乎与空气中近视镜度数相同.而当考虑水压力作用时,由于潜水镜片外表面发生形变,潜水员应佩戴度数较高的潜水镜.     

眼睛的光学构造和近视眼的矫治

近视对青少年的危害，首先表现为对学习产生不良影响．近视眼唯一安全有效的治疗方法是配戴眼镜，但眼镜会给孩子带来生活不便．笔者感觉有必要从物理的角度来谈谈眼睛的光学构造、眼睛的成像、视角与视力和近视眼的防治问题．     

栅极电势对强光场下石墨烯场效应管中电子隧穿的影响

利用时域有限差分方法研究了强光场下石墨烯场效应管中栅极电势对电子隧穿的影响. 在强光场下由于光学stark效应,石墨烯场效应管的完美手征透射被抑制.这种抑制除了 可以利用光场来调控外,也可以通过改变栅极电势的宽度、势垒高度等来调控. 研究了非方势垒中电子的隧穿. 研究发现,当电势的倾斜较小时,电子隧穿概率变化不大.而当电势倾斜很大时,电子隧穿概率急剧改变.     

驾驶员暗适应测试仪的研究

驾驶员暗适应测试仪由单片计算机系统、暗箱、强光产生部分及视标显示等部分组成。被测者在强光刺激之后,进入黑暗状态。同时测试仪开始计时,至被测者看清视标时停止计时。所计得的时间为其暗适应时间。测试仪测试的结果可显示在显示器上也可由打印机打印。实测结果表明驾驶员的暗适应时间有较显著的差异     

大气压等离子体针产生空气均匀放电特性研究

大气压空气放电由于脱离了真空装置,易于实现流水线生产,因而在工业上具有广泛的应用. 采用等离子体针装置在空气中产生了稳定的大气压均匀放电. 利用光谱法对等离子体的相关参数进行了空间分辨率测量,并通过光学方法对放电机理进行了研究. 结果表明,等离子体针产生的放电存在电晕放电和等离子体羽放电两种模式. 在稳定的等离子体羽放电模式中,发光分为强光区和弱光区. 弱光区放电的发展速度远大于强光区的发展速度,电子能量和电子密度均是弱光区比强光区大. 对均匀放电的气体温度和振动温度的研究表明,强光区放电遵循汤生击穿机理而弱光区为流光放电. 这些结果对大气压空气放电的工业应用具有重要意义. 关键词： 大气压均匀放电 等离子体针 发射光谱 放电机理     

提高菲涅尔全息图再现像质量的方法

拍摄菲涅尔全息图的记录过程中,照射在全息底片上的参考光为匀强光,而物光为非匀强光,导致干涉条纹的对比度不高.通过2次对光强分布的记录,制作出透光率同物光光强分布正相关的调制板,并加入参考光光路中,以此来改变参考光光强的分布,减小参考光与物光光强之差,提高了全息底片上干涉条纹的对比度,再现时获得了更为清晰的再现像.     

定第二主点变焦光学系统

根据透镜组基点性质和透镜组可变焦原理 ,设计定第二主点变焦光学系统。该系统用于视力矫正 ,在变焦过程中 ,“眼镜片光心”相对于眼睛的位置保持不变 ,是一种新型的光学变焦系统。用它可对近视、远视、散光等非正视眼进行快捷、准确的验光。     

基于光照强度叠加的视错觉现象分析

描述了一种新的视错觉现象,运用MATLAB软件对近视者观察等间距密集网格所产生的网格错位现象进行模拟计算分析,研究了近视程度、网格形状和网格间距对视觉错觉现象的影响规律。通过对不同情况下光线叠加产生的视觉图像进行理论推导,得到了与真实现象较相符的理论。从推导结论可知,在网格间距与近视度数成不同比例时会出现不同的视觉错位现象,且该现象的成因与泊松亮斑间有较深的联系。研究结果为进一步了解视觉错觉的产生机制和人眼对图像的处理过程提供了理论依据,为防治近视错觉可能导致的安全事故提供了帮助,并对存在相同结构的二维材料研究提供了参考价值。     

非局域克尔介质中空间光孤子的相互作用

研究了强非局域克尔介质中光束的演化规律，通过相位分析得到了空间孤子相互作用所满足 的非局域非线性薛定谔方程的简化近似模型，并获得了双光束传输的解析解.结果表明在传 输过程中相互作用的高斯光束的相位决定于它们的输入总功率.以振幅一强一弱共同传输的 高斯光束为例进行了具体研究，得到了强光和弱光的解析式，相位分析显示弱光在相当短的 传输距离之内能产生大的相移，可以通过对强光能量的调控来实现对弱光的相位调制. 关键词： 非局域克尔介质 空间光孤子 孤子相互作用 相位调制     

Infrared spectra of double-alkali silicate glasses

Infrared reflection spectra have been taken of bisilicate glasses in which one alkali oxide (Na₂O, K₂O) is gradually replaced by another while their total content is kept constant, and the electrical conductivity and density, of these glasses have been determined. The spectra of single-alkali glasses containing 16–20% of alkali and whose structure, according to some authors, is similar to that of bisilicate glasses, are also included. The main characteristic features of the spectra of double-alkali glasses do not confirm this assumption, but indicate that their structure approximates that of single-alkali glasses; nevertheless, the parts composing the microheterogeneous structure have an altered composition as compared with that of single-alkali glasses. Electrical conductivity passes through a minimum for all three combinations of the alkali oxides, while density passes through a weak maximum in the case of sodium-potassium glasses only.     

金属玻璃的热塑性成型

金属玻璃在其过冷液相区内表现出随着温度升高黏度逐渐降低的特性,因此可以对其进行热塑性加工.该性质颠覆了传统金属的加工成型方式,使得其在远低于传统金属材料加工的温度和应力作用下可以按照人们的要求进行成型.因此,一些具有低玻璃转变温度的金属玻璃又被称作金属塑料.另外,由于金属玻璃是一种无序结构材料,不存在位错、晶界等晶体缺陷,且热膨胀系数小,在热塑性成型中具有优异的尺寸精度,因此被认为是理想的微成型材料,有广阔的应用前景.本文系统介绍了金属玻璃的热塑性成型性质及其应用,从热塑性成型的基本概念出发,阐述了金属玻璃热塑性成型能力的评估指标、热塑性成型技术、热塑性微成型及其理论、热塑性微成型的应用等,对认识金属玻璃的热塑性及扩展其应用有重要的意义.     

Multiscale structures and phase transitions in metallic glasses:A scattering perspective

Amorphous materials are ubiquitous and widely used in human society, yet their structures are far from being fully understood. Metallic glasses, a new class of amorphous materials, have attracted a great deal of interests due to their exceptional properties. In recent years, our understanding of metallic glasses increases dramatically, thanks to the development of advanced instrumentation, such as in situ x-ray and neutron scattering. In this article, we provide a brief review of recent progress in study of the structure of metallic glasses. In particular, we will emphasize, from the scattering perspective, the multiscale structures of metallic glasses, i.e., short-to-medium range atomic packing, and phase transitions in the supercooled liquid region, e.g., crystallization and liquid-to-liquid phase transition. We will also discuss, based on the understanding of their structures and phase stability, the mechanical and magnetic properties of metallic glasses.     

Effect of some doping elements on the ionic conduction of mixed alkali-alumino-borosilicate glasses

Summary Some borosilicate glasses containing an equimolar ratio of different alkali types (K⁺ and Na⁺ ions) doped with 0.1 mole% R (R=Mn, Tb, Y, or Gd) were prepared. The results of d.c. electrical conductivity show that the absolute values of resistivities and the corresponding activation energies for the doped glasses are lower than those for glasses without doped ions. This behaviour is explained on the basis of the formation of elastic dipoles in such glasses and of the change of their fields owing to the existence of the doping ions. By thermal treatment of these glasses, it is found that the activation energies for the doped glasses are different from those obtained for glassess prepared without doping ions. This peculiarity is explained on the basis of the phase separation process in such glasses.     

The influence of sodium nanoparticles formation on luminescent properties of fluorophosphate glasses containing molecular clusters and quantum dots of lead selenide

The influence of sodium nanoparticles and secondary heat treatment conditions on the spectralluminescent characteristics of fluorophosphate glasses with PbSe molecular clusters and quantum dots is studied. Experiments with glasses containing no sodium nanoparticles show that their thermal treatment leads to the formation of molecular clusters with subsequent formation of quantum dots having an intense luminescence. The results of numerical simulation for glasses with sodium nanoparticles shows that heat treatment leads to formation of a sodium fluoride shell on the nanoparticles surface. It is shown that quenching of the luminescence of PbSe molecular clusters and quantum dots takes place in these glasses.     

Amorphous Coatings and Surfaces on Structural Materials

Metallic glasses show a unique combination of high strength, excellent corrosion, and wear resistances because of their amorphous structure having a short-range order. In spite of excellent properties, the application of metallic glasses is restricted because of their inherent limitations in the bulk form, including limited tensile ductility. Using metallic glasses as the coatings for structural applications is an attractive way of taking advantage of their superior properties. Additionally, metallic glass-based composites having crystalline phases embedded in a amorphous matrix have also shown improved properties. Thus, metallic glasses can be synthesized as the coatings or subjected to surface modification to provide functionally superior surfaces. This article is a review of metallic glass-based coatings and surface modification of metallic glasses to achieve functionally superior surfaces for structural applications. Essential theoretical concepts were discussed which influence the processing. Common ways of processing along with the influence of various processing parameters were explored. Some non-conventional techniques which emerged as a result of continued efforts were also taken into account. Corrosion and wear properties of these materials along with the underlying mechanisms were discussed in detail. Focus was given to the recent product level applications explored in the open literature. Current challenges in the field were reviewed and guidelines for the future developments were provided.     

超稳定玻璃

非晶态物质处于热力学非平衡状态,稳定性是非晶态材料应用的重要瓶颈,也是理论研究的关键问题.最近人们开发出相当于普通金属玻璃退火上百万年的"超稳定玻璃",为研究非晶态材料的稳定性和非晶态物质的本质提供了新契机.本文简要介绍超稳定玻璃的特点、形成机理以及其对非晶态物理学基本问题提供的新见解和新思路.     

TiO2对磷酸钙玻璃结构影响的Raman光谱研究

利用Raman光谱、X射线衍射(XRD)和热分析(DSC)技术研究了包容TiO2的磷酸钙玻璃的结构特点.结果表明,TiO2添加量小于3 mol%时,与磷酸钙形成均质玻璃.添加量为6～12 mol%时,玻璃基体中生成了Ca2P2O7和CaTi4(PO4)6品相.随着TiO2的加入,玻璃体系中发生了偏磷酸盐向焦磷酸盐和正磷酸盐的结构转变.TiO2添加量小于3 mol%时,加入TiO2增强了玻璃结构的内聚力,使得玻璃转变温度逐渐提高,玻璃的热稳定性增强.     

The effect of temperature on the luminescence spectra of potassium-aluminum borate and silicate glasses with copper(I) and silver ions

Luminescence and luminescence-excitation spectra of potassium-aluminum borate glasses containing copper(I) and silver ions have been investigated in the temperature range of 20–300°C. It is shown that the luminescence thermochromic effect, which manifests itself in a blue spectral shift of the luminescence bands with an increase in temperature, occurs in glasses of all types, reaching a value of 100 nm. Heating leads to a red shift of luminescence-excitation bands by 20 nm and their broadening. Luminescence quenching occurs in glasses exhibiting photochromic effect at room temperature. An increase in temperature leads to weakening and, finally, disappearance of the photochromic effect in these glasses with subsequent occurrence of the luminescence thermochromic effect.     

纳米结构非晶合金材料研究进展

迄今为止,人类社会新技术的发展主要是基于各种晶体材料(如金属、半导体等)的应用.晶体材料的性能可以通过改变它们的微观缺陷结构和/或微观化学结构来调控,但这对于当前的非晶材料而言却是难以实现的.新型的纳米结构非晶材料可以通过引入大量的非晶/非晶界面来改变非晶材料的微观缺陷结构和/或微观化学结构,从而实现对其性能的调控.本文主要讨论了目前纳米结构非晶合金材料的研究进展,包括其制备方法、结构特征和新性能.通过利用这些新特性,有可能会开启一个基于非晶材料的新技术时代.