Suppose we shine a beam of light at a mirror. The light strikes the mirror at a point P and is then reflected. What is the direction of the reflected beam? You may know the answer even if you have not formulated it mathematically: The incident and reflected beams make equal angles with the mirror.
麦克斯韦方程所预言的光是一种电磁辐射的认识使得光学和电磁学相统 一起来，包含可见光的波长范围仅仅是整个电磁波谱的一小部分，它跨越了 许多顺序。各个区域之间没有明显的界线；一个波长范围到另一个范围都是 连续的。 Nhomakorabea5
1.1 Models of Light: Rays and Waves
When sunlight is spread into a spectrum, we see the characteristic band of visible colors from red to violet. Beyond the violet edge of the visible spectrum are frequencies of radiation that exceed that of the violet. We use the name ultraviolet to describe this invisible extension of the spectrum. Beyond the red end of the visible spectrum lie frequencies below those we can see. These wavelengths make up the infrared region of the spectrum.
假设一束光照射到一个平面镜上。光线到达平面镜上一点P然后反射。反 射光线的方向是什么？即使你没有给出一个确切的数学计算，也可以知道答 案：入射光线和反射光线与平面镜成相等的角。
1.2 Reflection and Refraction
In optics it is an established convention to measure angles with respect to the normal, which is a line perpendicular to the surface, as indicated in Figure 1.4. The angle between the incoming ray and the normal is called the angle of incidence, θi. The angle between the outgoing ray and the normal is the angle of reflection , θr. Both angles are measured positive from the nomal. When these angles are measured, the angle of reflection is always found to equal the angle of incidence. Thus, the observed law of reflection is that the angle of reflection is equal to the angle of incidence, or θi= θr
虽然我们通常认为光是一种波动现象，但是这并不是可能存在的唯一观 点。除非遇到障碍物，一束由手电筒发出的光或者一束激光将沿直线传播， 光是由粒子束组成的观点与此相一致。我们把这种（光的）直线路径称为光 线。光线的模型使得我们可以用最简单的术语来解释透镜和平面镜形成的像。
3
1.1 Models of Light: Rays and Waves
However, light displays particle like characteristics when it interacts with matter, as it does, for example, when sunlight falls on a leaf and photosynthesis take place. The apparent conflict over this waveparticle duality can not be understood with just the theories of Newton or Maxwell, but is resolved by the twentiethcentury theory of quantum mechanics.
当日光被展开成一个波谱，我们可以看到从红色到紫色的可见光的特有 波段。可见光谱的紫色边缘之外便是大于紫光频率的辐射。我们把人眼看不 到的这段电磁波谱的延伸部分称为紫外线。可见光谱的红色边缘之外是小于 我们能够看到的频率的辐射。这部分波长构成了光谱的红外线波段。
1.1 Models of Light: Rays and Waves
English in Optoelectronic Information Technology
Chapter 1 Geometrical Optics
1.1 Models of Light: Rays and Waves
New Words & Expressions:
geometrical optics n. 几何光学 ultraviolet a.紫外线的 perpendicular a.&n.垂直的，垂直 specular reflection n.镜面反射 rearview n. 后视镜 index of refraction n. 折射系数 prism n. 棱镜，棱柱 coherent bundle n.相干光束 periscope n. 潜望镜 converging lens n.会聚透镜 unaided eye n.肉眼 focal length n.焦距 convex a. 凸的，凸面的 object distance n. 物距 photosynthesis n. 光合作用 infrared a.&n. 红外线的，红外线 angle of incidence n. 入射角 diffuse reflection n. 漫反射 paraxial approximation n.旁轴近似 critical angle n. 临界角 fiber optics n. 光纤 light guide n. 光导，光学纤维 image conduit n. 传像管 diverging lens n. 发散透镜 thin lens n. 薄透镜 optical axis n.光轴 concave a.凹的，凹面的 image distance n. 像距
电磁波谱的各个组成部分的基本表现都是相同的。只是它们的波长、频 率以及产生和探测它们的装臵不同。所有电磁波的行为可以由麦克斯韦方程 来预言，它是一种包括透镜、反射镜以及其他一些相关组件的形状和它们组 成的知识。例如，微波天线的设计遵循了望远镜设计的同样的基本原理。
7
1.2 Reflection and Refraction
The fundamental behavior of all components of the electromagnetic spectrum is the same. They differ only in their wavelengths and frequencies and in the kinds of devices that can be used to generated and detect them. The behavior of all electromagnetic waves can be predicted from Maxwell’s equations and a knowledge of the composition and shape of lenses, reflectors, and other components involved. For example, the design of microwave antennas follows the same underlying principles as does the design of telescope mirrors.
如图1.4所示，在光学上有一个确定的惯例就是说要根据法线来测定角度， 法线是一条垂直于镜面的直线。入射线和法线之间的角叫做入射角θi。出射 光线和法线之间的夹角叫做反射角θr。从法线起这两个角都是正角。测量时， 反射角总是等于入射角。因此，遵循反射定律：反射角等于入射角，即 θi= θr
9
1.2 Reflection and Refraction
然而，当与物质相互作用的时候，光显示出粒子态特性，例如，当日光 照在叶子上的时候光合作用就会发生。仅用牛顿或麦克斯韦的理论根本无法 解释光的“波粒二相性”上的明显分歧，但是这可用二十世纪的量子理论来 解释。
1.1 Models of Light: Rays and Waves
The realization that light was the same as the electromagnetic radiation predicted by Maxwell’s equations united the studies of electromagnetism and optics. The range of wavelengths that comprise visible light makes up only a small portion of the entire electromagnetic spectrum, which spans many orders of magnitude. There are no sharp dividing lines separating the various regions; there is just a continuous blending from one region to the next.