專業(yè)英語教案 光電信息工程專業(yè)用課件

1、專 業(yè) 英 語 教 案91 What is Optics（什么是光）Mankind has always been fascinated with light, thinking of it in ancient times as an uncontrollable, mystical force of nature. Science unraveled some of its mysteries as the inventions of mirrors, spectacles, and later microscopes and telescopes revealed to mankind

2、how light can be tailored to help people in their daily lives and in exploration, physically through the world and intellectually through science. u unraveled vt. 闡明, 解決u reveal vt. 展現(xiàn), 顯示, 揭示, 暴露u tailor n. 裁縫；vt. 剪裁, 縫制(衣服), 適應(yīng), 適合人類總被光迷住，在古代把它認(rèn)為成是一種無法控制的、神秘的自然力量?？茖W(xué)用一些發(fā)明來闡明光的神秘，例如有鏡子，眼鏡和后來展示給人類的顯微

3、鏡和望遠(yuǎn)鏡，以此來告訴我們光是如何被調(diào)整而用于幫助人們的日常生活和科學(xué)研究，以及幫助我們認(rèn)識世界和發(fā)展科學(xué)（身體上通過世界和智力通過科學(xué)）。Optics is the study of light and vision in science and engineering. Light is generally defined as the sector of the electromagnetic spectrum between the infrared and ultraviolet sectors that can be seen with the unaided eye.光學(xué)是在科學(xué)

4、和工程方面對光和視覺的研究。光一般被定義介于紅外和紫外之間、可被裸眼看到的電磁波譜的一部分。Optics plays an influential role in our lives:光學(xué)在我們的生活中起著重要作用：When you look into a mirror in the morning to comb your hair, when you see a rainbow after it rains, in medical devices that save lives, as you read this page, as you see, optics is at work.當(dāng)你

5、在早晨面對一面鏡子梳你的頭發(fā)時，當(dāng)你在雨后看到彩虹時，在那些挽救生命的醫(yī)學(xué)設(shè)備里，當(dāng)你讀這篇文章時，如你所見，是光在工作。Through these lessons, we hope to give you at least a peeku peek vi. 偷看；窺視；偷偷的一看, 一瞥我們希望通過下面的這些課程，可以使你對光學(xué)有個大概的了解：into geometrical optics; u geometrical adj. 幾何學(xué)的, 幾何的對幾何光學(xué)into physical optics; 對物理光學(xué)into the dual nature of light and past an

6、d current theories on it; 光學(xué)在過去和現(xiàn)代理論中的二重性into lenses and mirrors; 對透鏡和反射鏡into optical instruments; 對光學(xué)儀器into experiments that led to breakthroughs in the study of optics; u breakthrough n. 突破；突破性的發(fā)現(xiàn)，成就對在光學(xué)的研究過程中帶來突破的實驗；into how optics affects our daily lives and how it will affect the future.光學(xué)是如何影響

7、我們現(xiàn)在的日常生活，以及將如何影響未來。2 The Dual Nature of Light（光的二重性）The nature of light has been a controversy debated throughout the course of history. Two models evolved: the wave model and the particle model. Each model has taken an important dominating place, but neither has been disproved completely. Therefor

8、e, the scientific community has combined the two theories to form the wave particle duality, where characteristics from both models are attributed to light (the “wavicle”). These two seemingly contradicting models have been reconciled by a new theory of physics, called quantum electrodynamics, which

9、 is a quantum theory of the electromagnetic interactions between photons, electrons and muons (an elementary particle having a mass around 200 times greater than an electron). This model is also known as quantum theory of light. u controversy n. 爭論, 辯論, 論戰(zhàn)；u debate v. 爭論, 辯論u dominating adj. 專橫的, 主要

10、的, 獨裁的u disprove vt. 反證；反駁；證明為偽u wavicle 物量子波粒二象性u attribute vt. （與to連用）歸因于u contradict vt. 同矛盾, 同抵觸u reconcile vt. 使和解, 使和諧, 使順從；調(diào)解, 調(diào)停; 使相協(xié)調(diào)u quantum electrodynamics n. 物量子電動力學(xué)u electromagnetic interaction 電磁相互作用u muon n. 介子u elementary particle n. 核基本粒子光的本性在其整個歷史過程中是一場辯論。它們發(fā)展成兩種模式：波動模型和粒子模型。每一種模型

11、都有其重要的專用位置，但是沒有任何一個可以被完全證明為誤。因此，科學(xué)界將這兩種理論結(jié)合而形成波粒二象性，而來自于兩種模型的特征可以歸因于光（波粒二象性）。這兩種看似矛盾的模型被一種新的物理理論所統(tǒng)一，即量子電動力學(xué)，是一種光子，電子和介子（某一體積比單個電子大大約200倍的基本粒子）之間的電磁相互作用的量子理論。這個模型也被稱為光的量子理論。The Wave Theory of Light:光的波動理論The theory that light is transmitted via wave form was proposed by Christian Huygens in 1679. Acc

12、ording to his theory:光以波動形式傳播的理論是克里斯蒂安·惠更斯在1679年提出的，根據(jù)他的理論：（克里斯蒂安·惠更斯：（Christian Huygens 1629-1695）是與牛頓同一時代的科學(xué)家，是歷史上最著名的物理學(xué)家之一，他對力學(xué)的發(fā)展和光學(xué)的研究都有杰出的貢獻(xiàn)，在數(shù)學(xué)和天文學(xué)方面也有卓越的成就，是近代自然科學(xué)的一位重要開拓者。）l Light must travel through a medium. 光必須通過某種介質(zhì)進(jìn)行傳播。l This medium is called Ether, which is an omnipresent,

13、boundlessly resilient, massless medium unable to be sensed that was formerly theorized as the medium that carried light. 這種介質(zhì)稱為以太，它是一種無所不在的，有無限彈性的，無質(zhì)量的，不不能被感知的介質(zhì)，在從前它被理論化為能運(yùn)載光的介質(zhì)。l Light is a form of energy - Light travels in waveform in short wavelengths. 光是一種能量形式光在短波長方面以波形的形式傳播。u ether n. 天空醚, 大氣,

14、 蒼天, 物以太u omnipresent adj. 無所不在的, 同時遍在的u boundlessly adv. 無窮地, 無限地u resilient adj. 彈回的, 有回彈力的u massless adj. 物無質(zhì)量的u theorize v. 建立理論, 理論化u waveform n. 波形The Particle Theory of Light:光的粒子理論The theory that light is transmitted via corpuscular form was supported and advocated by Sir Isaac Newton. Accor

15、ding to this theory: light is composed of particles (“corpuscular”) that travel in a straight line at an extreme speed, they allow the eye experience vision when they are absorbed, and various colored particles all have differing sizes.u corpuscular adj. 微粒的，細(xì)胞的，小體的u advocate vt. 擁護(hù)；提倡； 主張u accordin

16、g to v. 依照光以粒子形式傳播的這一理論被艾薩克·牛頓先生支持并且提倡。依照這一理論：光是由粒子構(gòu)成的，它們沿直線并以高速傳播，當(dāng)它們被吸收時，就使得眼睛體驗視力，不同顏色的粒子都有著不同的尺寸。The Quantum Theory of Light:光的量子理論The theory that combines both the wave and particle models was suggested by Max Planck. According to this theory: light is absorbed or released in bundles of en

17、ergy called photons. u suggest vt. 建議, 提出, 使想起, 暗示結(jié)合波動模型和粒子模型的理論是由馬克斯·普朗克提出的。依照這一理論：光被以含有能量束的光子形式吸收或者釋放。Huygen's Principle:惠更斯原理Christian Huygens, a Dutch scientist, supported the concept that light is a wave motion that is transmitted through ether. Applying this theory, Huygens derived th

18、e laws of reflection and refraction.u derive vt. 獲得, 導(dǎo)出(from)克里斯蒂安·惠更斯，一位荷蘭科學(xué)家，他支持光是通過以太傳播的波形運(yùn)動的概念。應(yīng)用這一理論，惠更斯推導(dǎo)出反射定律和折射定律。Young's Double-Slit Experiment:楊氏雙縫實驗Thomas Young (1773-1829), an English scientist, also credited for helping translate the Rosetta Stone, conducted an experiment in 18

19、01, known as Young's double-slit experiment, that allowed him to show the wave nature of light and measure its wavelengths. The setup of this experiment is quite elegant-Light from a single source shines through two narrow, closely-placed slits for them to serve as two coherent light sources. (A

20、 coherent light source is one that makes light waves have a consistent phase relationship with each other-crest overlaps crest, trough overlaps trough) A screen is put behind these slits.u credit n. 信任, 信用, 聲望, 榮譽(yù), 財務(wù)貸方, 銀行存款vt. 相信, 信任, 把.歸給u conduct vt. 處理； 經(jīng)營；引導(dǎo)；實施u elegant adj. 優(yōu)雅的, 風(fēng)雅的, 雅致的, 文雅的

21、, 有風(fēng)度的；優(yōu)美的, 精彩的, 講究的u crest 【物】波峰; 振幅; 峰值, 最大值u trough 【物】波谷托馬斯·楊(1773-1829)，一位英國科學(xué)家，也相信可以幫助翻譯“羅塞塔碑”，在1801年進(jìn)行了一個實驗，就是著名的“楊氏雙縫實驗”，這一實驗使得他向人們展示了光的波動特性，并且可以測量波長。這個實驗的安裝十分講究來自同一光源的光將兩條狹窄、挨得很近的裂縫照亮，那么它們就象兩個相干光源（相干光源是指能夠使得兩束光相互有固定的位相關(guān)系，波峰與波峰重疊，波谷與波谷重疊）。（約5000年前，古埃及人發(fā)明了一種圖形文字，稱為象形文字。這種字寫起來既慢又很難看懂，國此大約

22、在3400年前，埃及人又演化一種寫得較快并且較易使用的字體。隨著時光的流逝，最終連埃及人自己也忘記了如何釋諱早期的那種象形文字了。若不是因為拿破侖大軍入侵埃及時，隨軍的法國古文字學(xué)家們的那次發(fā)現(xiàn)，極有可能至今考古學(xué)家們?nèi)詿o法辯認(rèn)這種文字。年，拿破侖率軍遠(yuǎn)征埃及時，他手下的一名軍官布夏爾帶領(lǐng)士兵，在羅塞塔城附近修筑防御工事時，發(fā)現(xiàn)了一塊黑色玄武巖斷碑。碑上用兩種文字三種字體刻著同一篇碑文。最上面用的是古埃及的象形文字，中間是古埃及的草書體象形文字（亦稱民書體文字），下面是希臘文字。這就是后來被世人稱之為“羅塞塔碑”的著名石碑。原來，“羅塞塔碑”上的碑文是公元前年埃及孟斐斯城的僧侶們，給當(dāng)時的國王

23、寫的一封歌功頌德的感激信。這位國王就是第十五王朝法老托勒密。他登上國王寶座后不久，取消了僧侶們欠交的稅款，并為神廟開辟了新的財源，對神廟采取了特殊的保護(hù)措施，給僧侶們帶來了一系列好處，所以很快贏得了僧侶們的敬仰。于是僧侶們寫了這封感激信，并用三種字體寫的兩種文字刻在這塊黑色玄武巖碑石上。小小的羅塞塔城，由于有了這塊借以解開埃及象形文字之謎的碑石而舉世聞名。不過，這塊著名的碑石早已不在該城，它被收藏在倫敦的大英博物館里了。）Now, if light consisted of particles, then the screen would reveal two bright lines whe

24、n the light illuminated through. Young, however, saw a center bright line and groups of symmetrical dark and bright edges and explained these groups to be marks of constructive and destructive interference. u constructive interference 相長干涉（當(dāng)兩列同相的波相遇，它們的波峰波谷會疊加成一個更大的波峰波谷，這現(xiàn)象稱為相長干涉。）u destructive inte

25、rference 相消干涉（當(dāng)兩列反相的波相遇，一列波的波峰會疊加在另一列波的波谷上，使兩個波互相抵消，這現(xiàn)象稱為相消干涉。）那么，若光由粒子組成，當(dāng)光通過狹縫時，在屏幕上將顯示兩條明亮的線。不過，（托馬斯·）楊看見中心是亮線，然后兩側(cè)是對稱的明暗邊緣，并且解釋這些條紋就標(biāo)志著相長干涉和相消干涉。So, since we've covered the basics, here is a diagram, which geometrically analyzes the experiment and explains some equations:因此，既然掌握了這些基本性質(zhì)，

26、這就是一張圖解，可以從幾何角度分析這些實驗并且解釋一些方程式：As the image indicates, the difference in the length of and is .正如圖像所顯示的，和的長度差為。Equations for Young's Double-Slit Experiment may be found here. 楊氏雙縫實驗的公式在這里就可以得到。Fresnel and Transverse Waves:Augustin Fresnel, in 1821 put forward results from experiments involving d

27、ouble refraction and polarized light suggested that light is a transverse wave, which is a wave where the vibrating part moves perpendicularly to the coming wave. Equations that he formulated, the Fresnel equations provide the amplitude of reflected and transmitted polarized light traveling at a pla

28、ne interface. u Transverse adj. 橫向的, 橫斷的u formulate vt. 用公式表示, 明確地表達(dá), 作簡潔陳述；v. 闡明u amplitude n. 【物】振幅u interface n. 分界面奧古斯丁·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(rèn)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）。他推導(dǎo)出的方程式稱為菲涅耳方程式，當(dāng)光遇到一個平面的分界面時，它可以給出反射光和透射偏振光的振幅。Further Developments:James Clerk Maxwell, a sci

29、entist 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 Pre

30、dict 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·克拉克·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。因此自此以后，光被認(rèn)為是電磁波譜的一部分。And later still, Einstein's theory of relatively helped throw out the idea of ether, which solved some problems dealing with the transverse v

31、ibrations of waves in liquids and gases.u throw out v. 伸出, 扔掉, 說出, 派出, 放出, 使出局, 使突出, 顯示并且直至后來，愛因斯坦的相對論幫助（我們）丟棄以太的概念，這就可以解決在液體和氣體中橫波遭遇的一些（無法解決的）問題。3 Geometrical Optics（幾何光學(xué)）Let's face it. Optics is pretty complicated. Light travels in waves, and waves are not easy to analyze. That's why in th

32、is 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。光學(xué)相當(dāng)錯綜復(fù)雜。光以波的形式傳播，而波也不容易分析。那也就是為什么在這門課中，我們將盡可能多地只用直線和角度而非波來描述反射和折射現(xiàn)象。Before we begin, an important concept to note is th

33、e 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。Now that you know the speed of light in meters per second, you will be able to apply it to many calculations that you may come across in geometrical optics and beyond. The two major phenomena in geometrical optics are reflection and refraction

34、, both of which we will not go into extreme detail in this lesson.u come across v. 來到, 偶遇；不期而遇, 交付u geometrical adj. 幾何學(xué)的, 幾何的既然你知道光速達(dá)到每秒米級，你將能把它用于你可能在幾何光學(xué)方面和其他方面遇到的許多計算問題。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(xì)的敘述。Wave Fronts and Rays波前和光線Waves, whether it is electromagnetic or other, are conveniently

35、 described in terms of wave fronts. A wave front is the line or surface defined by adjacent portions of a wave that are in phase. -If an arc is drawn along one of the crests of a circular water wave moving out from a point source, all the particles on the line will be in phase. u wave front 波前, 波陣面u

36、 in phase 【物】同相的地；同時協(xié)調(diào)的地u draw vt. 拉, 拖, 拉拖長, 拉成(絲等);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。波前是指一個波鄰近部分的線或面，它們是同相的。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。The curvature of a short segment of a spherical or circular wave front is small. The segment may be approximated as a linear wave

37、front or a plane wave front, just as we assume the surface of the Earth to be locally flat. 球面波前或圓波前中的一小部分的曲率是小的。這一部分可以近似地認(rèn)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。In a uniform medium wave fronts propagate outward from the source at a wave speed characteristic of the medium. For example, the speed of light tr

38、avels fastest in a vacuum: .在同一介質(zhì)中，波前以與光源發(fā)出的光同樣的介質(zhì)波速特性向外傳播。例如，光的速度在真空中傳播最快，為。The geometrical description of a wave in terms of wave fronts tends to neglect the fact that the wave is actually sinusoidal. The concept of a ray simplifies the wave description even further. A ray is a line drawn perpendi

39、cular to a series of wave fronts and pointing in the direction of propagation. A beam of light can be simplified and represented by a group of parallel rays or just a single ray. u in terms of adv.根據(jù), 按照, 用.的話, 在.方面u sinusoidal adj. 正弦曲線, 竇狀小管, 竇狀隙u simplify vt. 單一化, 簡單化u description n. 描寫, 記述, 形容,

40、種類, 描述u perpendicular adj. 直的, 正交的u represent vt. 代表, 象征u parallel adj. 平行的, 相同的, 類似的, 并聯(lián)的；n. 平行線, 平行面, 類似, 相似物用波前的概念對光波進(jìn)行幾何描述，趨向于忽略波是正弦曲線這一事實。一條光線的概念簡化為波的描述，甚至更進(jìn)一步。一條光線是一條被描述成垂直于一系列波前，并且沿著傳播方向的直線。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。Reflection and Refraction反射和折射We said that we are only going to talk about

41、light in terms of straight lines and rays in this lesson; 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 compose li

42、ght.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。在絕大部分場合，我們將繼續(xù)以直線和射線的方式談?wù)摴?，但是為了解釋反射的概念，我們將需要探討一點兒光用電磁波譜描述的情形。The two most important methods of light propagation are reflection and refraction. Reflection involves the absorption and re-emission of light by means of complex electromagnetic vibrations in the atoms of

43、 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。反射包含光的吸收和在反射介質(zhì)的原子中光以電磁波動的形式重新發(fā)射光的兩種情形。折射是指當(dāng)光從一種介質(zhì)進(jìn)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。A light ray incident on a surface is described by an angle o

44、f incidence. This angle is measured relative to a line perpendicular, or normal, to the reflecting surface. Likewise, the reflected ray is described by an angle of reflection. This relationship between these angles is given by the law of reflection:一條光線入射到一個表面上被描述成入射角。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。同樣地，

45、反射光線被描述為反射角。這兩個角度的關(guān)系可用反射定律給出：。The angle of incidence is equal to the angle of reflection.入射角等于反射角。Typically when a ray strikes a smooth surface separates two different transparent mediums (i.e. air and water) part of the ray is reflected and part of the ray is refracted. or transmitted into the seco

46、nd 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 mater

47、ials. 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

48、 material.u strike vt.到達(dá)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(dá)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。有兩種反射形式：鏡面反射，是指從一非常光滑表面以一定角度發(fā)生的反射；漫反射，是指向多個不同角度發(fā)生的反射。兩種方式的反射均可在不透明或透明的材料上。折射是指

49、當(dāng)（傳輸?shù)模┕獠ㄍㄟ^兩種透明介質(zhì)時光的傳播，而且改變了它的傳播方向。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。(index of refraction) 折射率The index of refraction of an optical material (also called the refractive index) denoted by n above, plays a central role in geometric optics. It is the ratio of the speed of light c in vacuum to the speed v i

50、n the material. 光學(xué)材料的折射率用上面的n表示，它在幾何光學(xué)中占有很重要的地位。它也等于真空中光速c與在介質(zhì)中光速v的比值。Wave speed v is inversely proportion to the index of refraction n. The greater the index of refraction in material, the slower the wave speed in that material. Failure to remember this point can lead to hopeless confusion! u inver

51、sely adv. 相反地, 倒轉(zhuǎn)地u proportion n. 比例, 均衡, 面積, 部分u confusion n. 混亂, 混淆光速v與折射率n成反比。材料的折射率越大，光速在其中的速度越慢。忘記這一點可能導(dǎo)致沒希望的混亂！The Laws of Reflection and Refraction反射定律和折射定律1. The incident, reflected and refracted rays and the normal to the surface all lie in the same plane.入射，反射，折射和表面的正交線都在同一平面內(nèi)。2. The angle

52、 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。3. The ratio of the sines of the angles, and , where both angles are measured from the normal to the surface, is equal to the inverse ratio of the two indexes of refraction: a

53、nd 正弦的比值等于兩種折射率的反比，而兩個角度都是從正交線向表面方向測量。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 Snell's law, after the Dutch scientist Willebrord Snell.這個實驗

54、結(jié)果， 事件和refrated 射線和正常的全部謊話在相同飛機(jī)內(nèi)的以及觀察， 被叫為折射定律或者斯內(nèi)爾的法律，在荷蘭科學(xué)家Willebrord斯內(nèi)爾之后。Total Internal Reflection:According to Snell's law, the larger the angle of incidence, the larger the angle of refraction, or the greater distance the refracted ray diverges from the norm.u diverge v. 偏離；背離：根據(jù)斯內(nèi)爾的定律，入射角

55、越大，折射角也越大，或者說折射線越偏離正交線。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.

56、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(dá)，包含，意味u boundary n. 邊界, 分界線u involve vt.

57、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; 固有的u total internal reflection 光全內(nèi)反射然而，對于這種偏離是有限制的。對于稱為臨界角的特殊入射角，其折射角為90度。這一角度意味著折射光線沿著發(fā)生折射的兩種介質(zhì)的分界線射出。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。這種情形就被稱為全內(nèi)反射。The critical angle necessary for total internal reflection to occur can be found by p

58、lugging 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。Fiber Optics works on the principle of total internal reflection. Light travels along a fiber, reflecting off the walls at an angle greater than the critical angle due to the narrow, linear shape of the fiber. This causes the light to be