【正文】 light. Earlier, it was done so by transmitting the signals via air, a prehistoric wireless munication.u prehistoric adj. 史前的；舊式的；陳腐的纖維光學(xué)基于用光傳送信號。這就是我們所知的一種反射類型，成為全內(nèi)反射。There are usually two types of fiber optics used: singlemode fibers, which transmit infrared laser light and have smaller inner cores, and multimode fibers, which transmit infrared lights of shorter wave lengths from a diode, a semiconductor device.u semiconductor n. [物] 半導(dǎo)體通常用到的光維有兩種：單模纖維，它可以傳輸紅外激光而且內(nèi)核較??；多模光纖，它能傳輸來自半導(dǎo)體二極管的較短波長的紅外光。A single optical fiber consists of three parts: the thin glass core where the light travels, the outer cladding, which reflects light into the core, and the plastic buffer, which protects the inner core and cladding from moisture and damage. A group of these optical fibers bundled up into an optical cable is protected by the jacket, or outer covering.u cladding n. 包層，鍍層u buffer n. 緩沖器；緩沖者；緩沖物；〈計〉緩沖區(qū)u jacket n. 【機】盒, 殼, 蓋, 保護罩, 膜, 蒙皮等u covering n. 覆蓋物，套，蓋，罩，殼一根光纖由三個部分組成：傳播光的細玻璃核心，將光反射回核心的外包層，保護內(nèi)部核心和包層免受潮濕和破壞的塑料緩沖區(qū)。4 Fiber Optics（纖維光學(xué)）What is Fiber Optics? Fiber optics is a new field that scientists and engineers have only recently discovered. The materials used are usually long strands of special glass called optical fibers bundled up into cables called optical cables, which are capable of transmitting light across distances.u strand n. 繩、線之一股, 線, 繩纖維光學(xué)是什么？纖維光學(xué)是科學(xué)家和工程師們最近才發(fā)現(xiàn)的一個新領(lǐng)域。由于狹窄而呈線性的光纖，光沿著一根光纖傳播，并以大于臨界角的某一角度全部反射。The critical angle necessary for total internal reflection to occur can be found by plugging in 90 degrees for the angle of refraction and simplifying to the equation on the right.必然發(fā)生全內(nèi)反射發(fā)生的臨界角可在堵住90度折射角時發(fā)現(xiàn)，而且可以簡化為下面的方程。如果入射角比臨界角大，或者換句話說，如果折射角大于90度，則光被全部反射。對于稱為臨界角的特殊入射角，其折射角為90度。There is a restraint to this divergence, however. With a particular angle of incidence called the critical angle, the resulting angle of refraction is 90 degrees. This angle carries the refracted light ray along the boundary between the two mediums involved in the refraction. If the angle of incidence is greater than the critical angle, or in other words, if the angle of refraction is greater than 90 degrees, the light is internally reflected. This state is known as total internal reflection.u restraint n. 抑制, 制止, 克制u carry vt. 表達，包含，意味u boundary n. 邊界, 分界線u involve vt. 包括，涉及u in other words adv. 換句話說u internally adv. 在內(nèi), 在中心；內(nèi)在的。Total Internal Reflection:According to Snell39。OR 或 (law of refraction) 折射定律This experimental result, together with the observation that the incident and refrated rays and the normal all lie in the same plane, is called the law of refraction or Snell39。2. The angle of reflection is equal to the angle of incidence for all wavelengths and for any pair of materials. 對所有波長和任何一對材料來說，反射角等于入射角。材料的折射率越大，光速在其中的速度越慢。它也等于真空中光速c與在介質(zhì)中光速v的比值。光學(xué)材料的折射率用n表示，是真空中光速c與材料中光速v的比值。兩種方式的反射均可在不透明或透明的材料上。Typically when a ray strikes a smooth surface separates two different transparent mediums (. air and water) part of the ray is reflected and part of the ray is refracted. or transmitted into the second medium. There are two forms of reflection: specular reflection, which entails the reflection at a definite angle from a very smooth surface, and scattered reflection, which entails the reflection at various different angles. Both forms of reflection may occur in either opaque or transparent materials. Refraction is the light propagation where the transmitted light passes through two transparent mediums and consequently changes its direction. An index of refraction or refractive index of an optical material, denoted by n, is the ratio of the speed of light, c, in vacuum to the speed v in the material.u strike u entail vt. 需要；使承擔(dān)u definite adj. 明確的, 一定的u opaque adj. 不透明的, 不傳熱的, 遲鈍的u transparent adj. 透明的, 顯然的, 明晰的u pass through v. 經(jīng)過, 通過u denote vt. 指示, 表示通常，當(dāng)光到達兩種不同透明介質(zhì)的光滑表面時，一部分光被反射，另一部分被折射，或者說傳播到第二種介質(zhì)中。這兩個角度的關(guān)系可用反射定律給出：。這一角度是指相對于反射表面垂直或正交的直線所成的角度。折射是指當(dāng)光從一種介質(zhì)進入另外一種介質(zhì)時，在其界面處波傳播方向發(fā)生變化的情形。The two most important methods of light propagation are reflection and refraction. Reflection involves the absorption and reemission of light by means of plex electromagnetic vibrations in the atoms of the reflecting medium. Refraction refers to the change in direction of a wave at a boundary where the wave passes from one medium into another. 光的兩種最重要傳播方式是反射和折射。 we lied. For the most part, we are still going to talk about light in terms of straight lines and rays in this lesson, but to explain the concept of reflection, we will need to talk a little bit about the electromagnetic waves that pose light.我們說在這門課中我們將只用直線和射線的方式談?wù)摴?；我們說謊了。一束光可以被簡化并且描述為一組平行的射線或僅僅一條光線。一條光線的概念簡化為波的描述，甚至更進一步。例如，光的速度在真空中傳播最快，為。這一部分可以近似地認為是線性波前或平面波前，正如我們假設(shè)地球表面的局部是平的一樣。如果一個光弧是沿著一個由點光源發(fā)出的圓形水波的振幅勾勒而成的，那么圓弧線上的所有點將是同相位的。描(圖), 繪制, 畫(線), 勾(輪廓) 波，不論它是電磁的還是其它的，通常用波前來描述。在幾何光學(xué)中，兩個主要的現(xiàn)象就是反射和折射，在這一課程里，我們將不作詳細的敘述。Before we begin, an important concept to note is the speed of light, or .在我們開始之前，需要要注意到的一個重要的概念，那就是光的速度，或者叫。光以波的形式傳播，而波也不容易分析。s why in this lesson we are going to try to explain as many phenomena of reflection and refraction as possible with only straight lines and angles instead of waves to represent light. 讓我們面對它。3 Geometrical Optics（幾何光學(xué)）Let39。And later still, Einstein39。麥克斯韋，一位研究電學(xué)和磁學(xué)（電磁學(xué)）方面的科學(xué)家，總結(jié)出4個麥克斯韋方程式，這一方程組可以給出電磁波在以太中的預(yù)測速度，這實際上是給出了光速c。Further Developments:James Clerk Maxwell, a scientist studying electricity and magnetism, formulated the four Maxwell equations, which gave a predicted speed of an electromagnetic wave through ether, which actually ended up being the speed of light, c. So from this point on, light was considered to be a part of the electromagnetic spectrum.u Predict v. 預(yù)知, 預(yù)言, 預(yù)報, 預(yù)測u end up v. 豎著, 結(jié)束, 死詹姆斯菲涅耳，在1821根據(jù)雙折射和偏振光方面的實驗提出結(jié)論，認為光是一個橫波，所謂橫波是指波的振動方向與傳播方向垂直（原文：波的振動部分垂直地移向來波）。s DoubleSlit Experiment may be found here. 楊氏雙縫實驗的公式在這里就可以得