用麦克斯韦方程组讨论晶体双折射现象

从晶体结构的各向异性、平面波的一般表达式以及麦克斯韦方程组出发,对晶体的双折射现象作 出了理论解释。理论分析表明,高级晶族两束光线的折射率都等于寻常光的折射率,满足折射定律,不 发生双折射现象;中级晶族两束折射光线中有且仅有一束光线满足折射定律,这束光线就是寻常光线(o 光),而另一束不满足折射定律的就是非常光(e光)。     

光的折射有什么规律

【现象观察】生活中经常会出现这些现象：图1水中鱼的位置看起来变浅了；图2在盛水的烧杯中放入一枚硬币，在烧杯的侧面却看到了两枚硬币；图3激光笔所发出的光经过玻璃砖后，传播方向发生了改变，【提出问题】光在两种透明介质的分界面上发生折射时，会有什么规律？猜想一：光从空气斜射入水或玻璃时，折射光线偏离法线。猜想的依据是水中的鱼（或硬币）看上去变浅了。猜想二：光发生折射时，入射光线、     

对双轴晶体的双折射现象的电磁理论解释

自然界的晶体多是双轴的,与单轴晶体一样,一束入射光在双轴晶体中一般也分成两束折射光,其振动面互相垂直,但这两束光都不遵从折射定律,且传播速度都随方向而变,一般不在入射面内,只有在晶体中的两个方向上,无论光的振动面有怎样的取向,它们的传播速度都相同,入射光不再分为两束,此即双轴晶体名称的由来。长期以来,一般书籍很少系统的讨论这一问题。本文应用电磁理论,从特殊情形出发来分析研究双轴晶体的双折射现象,这对于双轴晶体的理论研究具有一定的意义。     

光的反射和折射时能量守恒的论证

1　问题光通常是指能为人眼所感受到的一定波段的电磁波。广义地讲 ,光还包括红外线和紫外线。光作为一种电磁波 ,其振动矢量 (Ｅ 和Ｈ )与传播方向相垂直 ,即为一横波 ,具有偏振现象。在光的反射和折射时伴随着光的偏振 ,可叙述为 :一束光入射到媒质界面 ,在反射光中垂直入射面的振动 (垂直振动 )多于平行入射面的振动 (平行振动 ) ,而在折射光中 ,平行振动多于垂直振动。如此还不能充分说明光在介质表面上反射和折射时 ,能量是否守恒 ,以下以菲涅耳公式和电磁波理论来论证光反射和折射时的能量守恒。2　论证反射、折射示意图入射光线ａ ,…     

从透射光中观察牛顿环条纹不清晰的原因分析

讨论入射光在不同折射率媒质界面反射和折射后，其光强度的不同分布，分析从透射光中观察牛顿环条纹较模糊现象的原因。     

广告作品意蕴传播的特点

本文运用传播学、符号学方法,分析广告作品意蕴传播的特点.广告作品意蕴在传播的发生过程中趋于复杂化和多义化,在接受过程中主要受选择性定律影响,而在整个传播过程中,多因素的动态变化决定了何种含义会主导广告传播的最终效果.     

一道容易出错的光学作图题

在学习人教版八年级物理《光的折射》一节时，通过教师的演示实验得出：“光从空气斜射入水中或其他透明介质中时，折射光线向法线方向偏折。”教师接着提出另一个问题：“如果光从水中斜射入空气，是否发生折射现象？射到空气中的光线将向哪个方向偏折？画图表示你的想法。”学生画出了以下几种作图法：     

漂亮的压花玻璃

1.门窗上安装玻璃,是采光的需要。以往采用的大多是平板玻璃,现在,新颖奇妙的压花玻璃被越来越多地应用到建筑上。2.压花玻璃上有方格、圆点、菱形等各种花纹图案,非常好看。3.压花玻璃的光学性能和平板玻璃不同,隔着平板玻璃看东西很清楚,隔着压花玻璃就什么也看不见了。4.压花玻璃的凹凸花纹,实际上是各种透镜和棱镜的组合,光线经过压花玻璃的反射、折射后,变得相当紊乱了,无法成像,所以隔着它就看不清东西。5.浴室和厕所的门窗上装上了压花玻璃,可使室内光线充足,而室外的人却看不见室内,这样就可以不挂窗帘了!     

探究全反射 揭秘小魔术

<正>提出问题:我们知道,光从空气斜射入玻璃等透明介质中,折射光线靠近法线偏折,折射角小于入射角。根据光路可逆,光从玻璃等透明介质斜射入空气中,折射光线远离法线,折射角大于入射角。当入射角逐渐增大时,折射角也逐渐增大,始终大于入射角。当入射角增大到某一个角度时,折射角增大到了90°,如果再继续增大入射     

《尚书》农业术语英译的文化折射及其认知识解

《尚书》为"七经之冠冕",是中华文化的元典。基于已建成的《尚书》英汉平行语料库,以定量方式考察理雅各和彭马田两个英译本对农业术语的文化折射。研究发现:理译本在四个分项和整体上的文化折射率均低于彭译本,文化忠实度较高,相比而言,彭译本文化忠实度较低,与原文的文化距离较大。从识解理论的辖域与背景、视角、突显以及详略度四个维度入手,可以阐释产生文化折射差异的认知机制,对于中国古典农业文化外译与传播有一定启发。     

Measurements of the imaginary part of the refractive index between 300 and 700 nanometers for mount st. Helens ash

The absorption properties, expressed as a wavelength-dependent imaginary index of refraction, of the Mount St. Helens ash from the 18 May 1980 eruption were measured between 300 and 700 nanometers by diffuse reflectance techniques. The measurements were made for both surface and stratospheric samples. The stratospheric samples show imaginary index values that decrease from approximately 0.01 to 0.02 at 300 nanometers to about 0.0015 at 700 nanometers. The surface samples show less wavelength variation in imaginary refractive index over this spectral range.     

大气气溶胶介电常数的研究

由于气溶胶的介电常数不易直接测量,气溶胶的复折射指数的实部与其介电常数之间存在的一定关系,利用这一关系,可以用气溶胶的复折射指数的实部来求出其介电常数,并对4种基本粒子、3种常见类型的气溶胶以及任意体积比混和建立的气溶胶类型的介电常数进行了研究。     

Giant birefringent optics in multilayer polymer mirrors

Multilayer mirrors that maintain or increase their reflectivity with increasing incidence angle can be constructed using polymers that exhibit large birefringence in their indices of refraction. The most important feature of these multilayer interference stacks is the index difference in the thickness direction (z axis) relative to the in-plane directions of the film. This z-axis refractive index difference provides a variable that determines the existence and value of the Brewster's angle at layer interfaces, and it controls both the interfacial Fresnel reflection coefficient and the phase relations that determine the optics of multilayer stacks. These films can yield optical results that are difficult or impossible to achieve with conventional multilayer optical designs. The materials and processes necessary to fabricate such films are amenable to large-scale manufacturing.     

External reflection from omnidirectional dielectric mirror fibers

We report the design and fabrication of a multilayered macroscopic fiber preform and the subsequent drawing and optical characterization of extended lengths of omnidirectional dielectric mirror fibers with submicrometer layer thickness. A pair of glassy materials with substantially different indices of refraction, but with similar thermomechanical properties, was used to construct 21 layers of alternating refractive index surrounding a tough polymer core. Large directional photonic band gaps and high reflection efficiencies comparable to those of the best metallic reflectors were obtained. Potential applications of these fibers include woven fabrics for radiation barriers, spectral authentication of cloth, and filters for telecommunications.     

对称结构一维三元光子晶体的透射谱和电场分布

用传输矩阵法研究对称结构一维三元光子晶体(ABC)n(CBA)n的透射谱及内部电场分布,结果发现:随着n的增加,出现的单条透射峰越加锋锐,光子晶体内部局域场越强;当增加介质层A或C的折射率时,透射峰向长波方向移动,且随着nA的增加,光子晶体内部局域场逐渐减弱,而随着nC的增加,光子晶体内部局域场则逐渐增强.这些传输特性可为光子晶体设计和制造新型光学器件提供参考.     

Broadband light bending with plasmonic nanoantennas

The precise manipulation of a propagating wave using phase control is a fundamental building block of optical systems. The wavefront of a light beam propagating across an interface can be modified arbitrarily by introducing abrupt phase changes. We experimentally demonstrated unparalleled wavefront control in a broadband optical wavelength range from 1.0 to 1.9 micrometers. This is accomplished by using an extremely thin plasmonic layer (~λ/50) consisting of an optical nanoantenna array that provides subwavelength phase manipulation on light propagating across the interface. Anomalous light-bending phenomena, including negative angles of refraction and reflection, are observed in the operational wavelength range.     

Clouds of venus: evidence for their nature

The linear polarization of sunlight multiply scattered by the atmosphere, and cloud particles of Venus has been computed and compared with observations over the wavelength range from the ultraviolet to the infrared region. The following properties of the visible cloud layer are derived: the refractive index of the cloud particles is 1.45 +/- 0.02 at a wavelength of 0.55 micron, and there is an indication of a slight decrease in the value from the ultraviolet to the near-infrared region; the mean particle radius is very near 1 micron, and most of the particles are spherical; the cloud layer occurs high in the atmosphere where the pressure is about 50 millibars (equivalent to an altitude of approximately 20 kilometers on the earth). The results for the index of refraction eliminate the possibility that the visible clouds are composed of pure water or ice.     

基于透射型体布拉格光栅衍射效率的研究

基于Kogelnik耦合波理论,推导了透射体布拉格光栅的衍射效率方程,数值仿真分析了折射率调制幅度、晶体厚度、相位失配参量、角度偏移量和波长偏移量等光栅写入参数对体光栅衍射效率的影响.结果表明:当入射波和衍射波没有发生相位失配时,衍射效率最大;当以布拉格角入射时,衍射效率将随介质的厚度和折射率的空间调制幅度的增加而增加;当入射光满足布拉格条件时,不同厚度和折射率调制幅度的体光栅衍射效率为100%;只要入射光偏离布拉格条件一个很小的量,体光栅衍射效率就会迅速下降;当偏离量超出一定范围,衍射效率就降低为0.同时,并非是体光栅折射率的空间调制幅度越深,衍射效率越高.     

The cosmological kibble mechanism in the laboratory: string formation in liquid crystals

The production of strings (disclination lines and loops) has been observed by means of the Kibble mechanism of domain (bubble) formation in the isotropic-nematic phase transition of the uniaxial nematic liquid crystal 4-cyano-4'-n-pentylbiphenyl. The number of strings formed per bubble is about 0.6. This value is in reasonable agreement with a numerical simulation of the experiment in which the Kibble mechanism is used for the order parameter space of a uniaxial nematic liquid crystal.     

基于单模光纤偏芯结构的光纤折射率传感器研究

基于迈克尔逊(Michelson)干涉仪(MI)原理,结合光纤传感器的特性,设计和实现了一种单模光纤(SMF)偏芯干涉仪结构光纤折射率传感器,并针对蔗糖溶液进行了折射率的测量。实验结果表明:这种传感器的传感范围在1.33～1.39时,特征波长与外界折射率有单调的递减变化关系,蔗糖折射率每变化0.01时,特征波长平均变化约为0.12nm。这种传感器结构简单,灵敏度较高,能够实现液体折射率与浓度变化的在线检测。