专业英语第4讲.

1、English in Optoelectronic Information Technology Chapter 1 Geometrical OpticsChapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语New Words & Expressions:algebraical a. 代数学的，代数的代数学的，代数的 linear magnification n. 线性放大率线性放大率 derivation n.引出，来历，出处引出，来历，出处 thin-lens equation n. 薄透镜方程薄透镜方程convention n.协定，惯例协定，

2、惯例 dime n. 一角硬币一角硬币image-forming devices n.成像设备成像设备 spherical aberration n. 球差球差isosceles a. 二等边的二等边的 analogous a.类似的，相似的类似的，相似的parabolic mirror n. 抛物柱面镜抛物柱面镜 aberrations n. 失常失常,象差象差paraxial approximation n. 旁轴近似旁轴近似 radii n. 半径半径binocular n.双筒望远镜双筒望远镜 chromatic aberration n. 色差色差 troublesome a. 麻烦

3、的，棘手的麻烦的，棘手的 grinding n. 磨的，碾的磨的，碾的aspherics n. 非球面镜头非球面镜头 condenser n. 冷凝器，电容器冷凝器，电容器Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses An optical lens is a piece of glass or other transparent material used to direct or control rays of light. Usually the lens surfaces are spherical, a

4、lthough other shapes (parabolic, cylindrical, etc.) are not uncommon. The refraction of light at the surface of a lens depends on its shape, its index of refraction, and the nature of the medium surrounding it (usually air), in accordance with Snells law. 一块光学透镜是一块用于引导或者控制光线的玻璃或者其他透明材料。一块光学透镜是一块用于引导

5、或者控制光线的玻璃或者其他透明材料。透镜表面形状一般都是球面的，尽管其他的形状（抛物线、圆柱形）也会常透镜表面形状一般都是球面的，尽管其他的形状（抛物线、圆柱形）也会常见到。光在透镜表面的折射取决于它的形状，它的折射系数，以及周围介质见到。光在透镜表面的折射取决于它的形状，它的折射系数，以及周围介质（通常是空气）的性质，这跟斯涅尔定律是一致的。（通常是空气）的性质，这跟斯涅尔定律是一致的。 Because lenses can be used to produce images of objects, they form the basis of most optical instrument

6、s, from cameras and projectors to microscopes and telescopes. In fact, the eye itself contains a lens and functions as an optical system. 因为透镜可以产生物体的像，它们是构成大部分光学仪器的基础元件，因为透镜可以产生物体的像，它们是构成大部分光学仪器的基础元件，从相机、投影仪到显微镜和望远镜。事实上，眼睛本身包含着一个透镜，并从相机、投影仪到显微镜和望远镜。事实上，眼睛本身包含着一个透镜，并具有一个光学系统的功能。具有一个光学系统的功能。3Chapter 1

7、. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses There are only a few distinct ways of combining flat, convex, and concave surfaces to form a single lens. If you hold a single lens like one of those in the figure at a moderate distance in front of your eye and look at something through it, yo

8、u can make several observations. 目前仅有几种不同的方法把平面、凸面和凹面组合成一个单透镜。如果目前仅有几种不同的方法把平面、凸面和凹面组合成一个单透镜。如果你把如图所示的某一个单透镜放在你眼前适当的距离来观察某些东西，你可你把如图所示的某一个单透镜放在你眼前适当的距离来观察某些东西，你可以做出几种观察。以做出几种观察。4 Consider first, lenses that are thicker in the center than at their edges Fig.1.10(a). These are called positive or conve

9、rging lenses, because they refract incident parallel rays so that they converge on a focal point located on the oppsite side of the lens. A distant object viewed through such a lens appears smaller and inverted if the lens is held some distance from the eye. 首先考虑图首先考虑图1.10（a）中中间比边缘厚的透镜。因为它们把入射平行光折）中

10、中间比边缘厚的透镜。因为它们把入射平行光折射后会聚在透镜另一侧的焦点上，故它们被称为正透镜或会聚透镜。通过这射后会聚在透镜另一侧的焦点上，故它们被称为正透镜或会聚透镜。通过这个透镜看远处的物体会显得比较小，若把该透镜保持离人眼一定的距离，则个透镜看远处的物体会显得比较小，若把该透镜保持离人眼一定的距离，则情形相反。情形相反。Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses An object held close to the same lens appears erect and enlargedFig.1.10

11、 (c). Now look at lenses that are thinner in the center than at their edges, such as those in Fig.1.10 (d). 靠近同一个透镜的物体看起来是正立的、放大的。现在看图靠近同一个透镜的物体看起来是正立的、放大的。现在看图1.10（d）所）所示的透镜，它们中间比边缘薄。示的透镜，它们中间比边缘薄。 These are called negative or diverging lenses, because they refract incident parallel rays so that th

12、ey appear to diverge from a focal point located on the incident side of the lens. 这些被称为负透镜或者发射透镜，因为它们折射入射平行光时，（折射这些被称为负透镜或者发射透镜，因为它们折射入射平行光时，（折射线）看起来像是入射一侧的虚拟焦点发出的。线）看起来像是入射一侧的虚拟焦点发出的。 Any object viewed through such a lens always appears erect and smaller than when viewed with the unaided eye. The i

13、mage remains erect no matter how far the object is from the lens or how far the lens is from the eye. 用肉眼通过这样的透镜观察任一个物体时，感觉物体是正立缩小的。不用肉眼通过这样的透镜观察任一个物体时，感觉物体是正立缩小的。不管物体距离透镜多么远或者人眼距离透镜多么远，看到的像都是正立的。管物体距离透镜多么远或者人眼距离透镜多么远，看到的像都是正立的。5Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses Lets t

14、ake a converging lens and allow light from the sun to fall on it. Because the sun is so far away, the rays striking the lens are essentially parallel to one another. 我们取一个会聚透镜，让太阳光照射它。由于太阳非常遥远，光线基本是我们取一个会聚透镜，让太阳光照射它。由于太阳非常遥远，光线基本是相互平行着射到透镜上。相互平行着射到透镜上。 When these light rays strike the lens parallel

15、to its axis of symmetry, the rays converge to a point called the focal point of the lensFig1.11. Thus, we can say that any ray incident on a converging lens and parallel to its optical axis(that is, the symmetry axis of the lens) passes through the focal point upon leaving the lens. A lens whose thi

16、ckness is small in comparison with its focal length is called a thin lens. 当这些光平行于对称轴射到透镜上，光线会聚到一个叫做透镜焦点的点上。当这些光平行于对称轴射到透镜上，光线会聚到一个叫做透镜焦点的点上。因此，我们可以说平行光轴入射到会聚透镜上的任意光线，出射后通过透镜的因此，我们可以说平行光轴入射到会聚透镜上的任意光线，出射后通过透镜的焦点。那些厚度和焦距相比很小的透镜称为薄透镜焦点。那些厚度和焦距相比很小的透镜称为薄透镜。6Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术

17、专业英语 The distance from the center of the thin lens to the focal point is the focal length of the lens. Each lens has its own particular focal length determined by the curvature of its surfaces and the index of refraction of the material from which it is made. 从薄透镜的中心到焦点的距离称为透镜的焦距。每个透镜从薄透镜的中心到焦点的距离称为

18、透镜的焦距。每个透镜 都有自己的特都有自己的特定焦距，焦距大小由它的表面曲率和制作材料的折射率决定定焦距，焦距大小由它的表面曲率和制作材料的折射率决定。 There is a symmetry to the passage of light through a thin lens. Any light ray entering the converging lens from the left parallel to the optical axis Fig1.11 (a) passes through the focal point F on the right after it leave

19、s the lens. 通过薄透镜的光线具有对称性。任何平行于光轴的光线从左侧入射到会通过薄透镜的光线具有对称性。任何平行于光轴的光线从左侧入射到会聚透镜，出射时经过右面的焦点聚透镜，出射时经过右面的焦点F。 Conversely, any ray coming from the focal point on the right and striking the lens emerges parallel to the axis Fig1.11(b). Parallel light entering the same lens from the right converges to a poi

20、nt F on the left of the lens Fig1.11(c). 相反地，任何从右面来自焦点的光线入射到透镜上出射时平行于光轴。平相反地，任何从右面来自焦点的光线入射到透镜上出射时平行于光轴。平行光从右面入射到同一个透镜，将聚焦到透镜左侧的一点行光从右面入射到同一个透镜，将聚焦到透镜左侧的一点F。apostrophe1.5 Thin Lenses7Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses For a thin lens, the distance f and f from the cente

21、r of the lens to F and F are the same, even though the lens surfaces are not identical. 对于薄透镜，从透镜的中心到焦点对于薄透镜，从透镜的中心到焦点F和和F 的距离的距离f 和和f 是相同的，即使透镜是相同的，即使透镜的两个表面不一定完全相同。的两个表面不一定完全相同。 Thus, we consider a thin lens to have two identical focal lengths, one on either side of the lens. In the remainder of t

22、his chapter, we will consider all lenses to be thin lenses. 这样，我们认为一个薄透镜在其两侧拥有两个相等的焦距。在本章接下来这样，我们认为一个薄透镜在其两侧拥有两个相等的焦距。在本章接下来的内容中，我们将认为所有的透镜均为薄透镜。的内容中，我们将认为所有的透镜均为薄透镜。 In addition, we will assume that the incident light rays are nearly parallel to the lens axis(the paraxial approximation). Later, in

23、Section 1.9, we discuss some of the ways in which real lenses differ from our idealized thin lens.另外，我们将假定入射光线近似平行于光轴（旁轴近似）。接下来，在另外，我们将假定入射光线近似平行于光轴（旁轴近似）。接下来，在1.91.9节节我们将讨论区分现实透镜和理想透镜的几种方法。我们将讨论区分现实透镜和理想透镜的几种方法。88Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses Parallel light incide

24、nt on a concave lens parallel to its optical axis diverges Fig.1.12(a). After passing through the lens, the light behaves as if it came from a point source located at F. Thus f is the focal length for this lens. 沿凹透镜光轴入射的平行光线将会发散。穿过透镜后，貌似光线是从一个沿凹透镜光轴入射的平行光线将会发散。穿过透镜后，貌似光线是从一个点光源点光源F发出的。因此发出的。因此f是这个透

25、镜的焦距。是这个透镜的焦距。 Fig.1.12(b) shows that the same lens refracts light directed toward the focal point on the other side so that the rays emerge parallel to the optical axis after passing through the lens. 图图1.12(b)展示了朝向另一侧的焦点会聚的光线，经同一个透镜折射后出射展示了朝向另一侧的焦点会聚的光线，经同一个透镜折射后出射光线平行于光轴。光线平行于光轴。99Chapter 1. Geom

26、etrical Optics光电信息技术专业英语光电信息技术专业英语1.5 Thin Lenses An ordinary piece of flat glass, such as a window with parallel faces, passes light without changing its direction. Although the direction of the ray does not change, the ray is displaced laterally. 一块普通的平面玻璃，例如平面窗户（玻璃），光不改变方向地穿过它。一块普通的平面玻璃，例如平面窗户（玻璃

27、），光不改变方向地穿过它。尽管光线的方向没有改变，但是光线尽管光线的方向没有改变，但是光线 向一侧平移。向一侧平移。 At the center of a lens, the front and back surfaces are parallel, so to a very good approximation, a light ray striking the center of the lens goes through the lens undeviated. 在一个透镜的中心，前后表面是平行的。故作一个很好的近似，照射到透在一个透镜的中心，前后表面是平行的。故作一个很好的近似，照射到

28、透镜中心的光无偏离地通过透镜。镜中心的光无偏离地通过透镜。 If the incoming ray does not make too large an angle with the axis and if the lens is thin, the offset in the ray is negligible. 如果入射光和光轴所成夹角不太大，并且透镜是薄透镜，光线的偏移就可如果入射光和光轴所成夹角不太大，并且透镜是薄透镜，光线的偏移就可以忽略不计。以忽略不计。1010Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating

29、 Images by Ray Tracing The major usefulness of lenses is their ability to form images of an object. The object may be self-luminous, giving off its own light (like the sun or a light bulb), or it may reflect the light that falls on it (like an apple or a page of this book). 透镜的用处在于他们可以使一个物体成像。物体可以是自

30、发光的，发出自透镜的用处在于他们可以使一个物体成像。物体可以是自发光的，发出自己的光（如太阳或者一个灯泡），或者它可以反射照射在它身上的光（己的光（如太阳或者一个灯泡），或者它可以反射照射在它身上的光（比如一比如一个苹果或者这本书的一页个苹果或者这本书的一页）。）。 In either case, an image of the object is formed where light rays that come from points on the object intersect or at the points from which the rays appear to origina

31、te. 在（这两者）任何一种情况下，物体的像都会形成，要么来自发光物体的在（这两者）任何一种情况下，物体的像都会形成，要么来自发光物体的横断面上的点，要么来自于光线看起来发光的点。横断面上的点，要么来自于光线看起来发光的点。11Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing When the light rays actually intersect at the image, we call this a real image. A screen placed at a r

32、eal image point would show the image in the same way that pictures appear on a moive screen. 当光线实际交汇于像上，我们称之为实像。把一个屏放置在实像点，将会当光线实际交汇于像上，我们称之为实像。把一个屏放置在实像点，将会像在影幕上播放图片那样显示出该像。像在影幕上播放图片那样显示出该像。 A virtual image is formed at a point where the light appears to converge, or from which it appears to come.

33、虚像形成于光线看起来会聚的地方，或者光线看起来来自的地方。虚像形成于光线看起来会聚的地方，或者光线看起来来自的地方。 If you place a screen at the position of a virtual image, no image is observed on the screen, for the light rays dont actually intersect there. 如果在虚像处放置一个屏，并不能在屏上观察到该像，因为光线实际上并如果在虚像处放置一个屏，并不能在屏上观察到该像，因为光线实际上并没有照射到那。没有照射到那。12Chapter 1. Geomet

34、rical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing An example of images in a mirror may help to explain virtual images. 镜子中的像这个例子可以帮助我们来解释虚像。镜子中的像这个例子可以帮助我们来解释虚像。 If you stand one meter in front of a mirror, your image appears to lie one meter behind the mirror. However, you will not

35、 find an image on a screen placed at the image position one meter behind the mirror. 如果你站在一个镜子前面一米处，你的像好像位于镜子后面一米处。然而，如果你站在一个镜子前面一米处，你的像好像位于镜子后面一米处。然而，你将不会在置于像的位置处的屏幕上看到你的像。你将不会在置于像的位置处的屏幕上看到你的像。 13Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing An object, such as

36、 a pencil, reflects light rays in all directions from all points of the pencil. We illustrate this in Fig. 1.14 by using arrows from the tip of the pencil to represent light rays. 一个物体，比如一支铅笔，从它自身各点向所有方向反射光线。我们在图一个物体，比如一支铅笔，从它自身各点向所有方向反射光线。我们在图1.14中加以说明，用从铅笔尖端的箭头表示光线。中加以说明，用从铅笔尖端的箭头表示光线。 However, to

37、 locate the image of the pencil formed by a thin lens, you dont need to trace the light rays from all over the object. Instead, you can locate the image by tracing three particular rays from a point on the object. 然而，给薄透镜所成铅笔像定位，你不需要用所有的光线进行追迹。相反，然而，给薄透镜所成铅笔像定位，你不需要用所有的光线进行追迹。相反，你可以从过物体上一点的三条特定光线来定位

38、它的像。你可以从过物体上一点的三条特定光线来定位它的像。14Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing Fig.1.14(a) shows these rays refracted by a converging lens; Fig.1.14(b) shows them for a diverging lens. 图图1.14（a）描述了这些光线被一个会聚透镜折射；图）描述了这些光线被一个会聚透镜折射；图1.14(b)描述了这些描述了这些光线被一个发散透镜折射。光线被一个

39、发散透镜折射。 In each case the focal length of the lens and the distance from the object to the center of the lens (the object distance) determine the distance of the image from the lens (the image distance). 在每一种情况下，透镜的焦距和物体到透镜中心的距离（物距）决定了像在每一种情况下，透镜的焦距和物体到透镜中心的距离（物距）决定了像到透镜的距离（像距）。到透镜的距离（像距）。15Chapter 1

40、. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing Although we can use these three specific rays to locate the position of the image, the actual formation of the image is much more complex. 虽然我们可以用这三条特定的光线来定位所成像，但实际上该像的形成要虽然我们可以用这三条特定的光线来定位所成像，但实际上该像的形成要复杂的多复杂的多。 The light fr

41、om each point on the object converges to form the corresponding point on the image. Rays from a single point on the object strike the entire lens surface. 物体上每一点的光线会聚形成像上相应的点。物体上一点发出的光线照射物体上每一点的光线会聚形成像上相应的点。物体上一点发出的光线照射到整个透镜表面。到整个透镜表面。 Conversely, any small area of the lens surface is struck by rays

42、 coming from every point on the object. 相反地，透镜上任何一个小区域都被物体上每一点发出的光线照射到。相反地，透镜上任何一个小区域都被物体上每一点发出的光线照射到。16Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing All of the rays striking each small area are focused to form the image. Thus, the image is composed of contribut

43、ions of light that pass through every part of lens. 照射到每一小区域的所有光线被聚焦来形成像。因此，像照射到每一小区域的所有光线被聚焦来形成像。因此，像是由穿过透镜每是由穿过透镜每一部分的光形成的。一部分的光形成的。 For this reason, blocking out part of the lens does not cast a shadow on the image, but simply reduces the brightness of the image be restricting the amount of light

44、 that gets to it. 正因为这个原因，遮住透镜上的部分光线并不能在像上产生阴影，只不过正因为这个原因，遮住透镜上的部分光线并不能在像上产生阴影，只不过是到达像的光线数量变少而导致了像的亮度减小。是到达像的光线数量变少而导致了像的亮度减小。 17Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing When the rays are close to and nearly parallel to the axis (the paraxial approximation)

45、, a small planar object perpendicular to the optical axis is imaged by a thin lens in to a planar region that is also perpendicular to that axis. 当光线靠近光轴并且近似平行于它时（旁轴近似），垂直于光轴的物平面当光线靠近光轴并且近似平行于它时（旁轴近似），垂直于光轴的物平面经薄透镜成像，其像也位于垂直于光轴的平面内经薄透镜成像，其像也位于垂直于光轴的平面内。 Thus, all points in the object plane are repre

46、sented as points in an image plane. When the object is three-dimensional, like the pencil in Fig. 1.14(a), points located in different object planes dont focus in a single image plane. 这样，物平面内的所有点被像平面内的点来描述。当物体是三维的，如图这样，物平面内的所有点被像平面内的点来描述。当物体是三维的，如图1.14(a)1.14(a)中的铅笔，位于不同物平面内的点并不能聚焦在同一个像平面上。中的铅笔，位于不

47、同物平面内的点并不能聚焦在同一个像平面上。 18Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing For instructional purposes we restrict our discussion to planar objects and their planar images. Thus, we normally represent objects and images with simple arrows perpendicular to the optical

48、axis. 出于讲授目的，我们仅限于讨论平面物体和它们的平面像出于讲授目的，我们仅限于讨论平面物体和它们的平面像。因此，我们用。因此，我们用垂直于光轴的简单箭头来标准地描述物体和像。垂直于光轴的简单箭头来标准地描述物体和像。 Let us state the graphical procedure to follow for locating the image from a given lens when you know the objects position. 在在知道物体的位置的情况下，让我们列举一下定位由给定的透镜成的像的知道物体的位置的情况下，让我们列举一下定位由给定的透镜成的像

49、的流程图。流程图。 19Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing In the next section, we will describe how to calculate the image height and location algebraically from the graphical ray diagram. You should refer to both parts of Fig.1.14 as you read these steps. 在下一节，

50、我们将在下一节，我们将描述如何描述如何通过射线图用代数法计算像高和位置通过射线图用代数法计算像高和位置。当你读。当你读到这些步骤时，图到这些步骤时，图1.14的两部分均会涉及到。的两部分均会涉及到。 A. Select an appropriate scale (meters, centimeters,etc.) and mark the position of the lens on the optical axis (also referred to as the principal axis). 选择选择适当的刻度（米，厘米，等），并且标定透镜在光轴（也作为主轴被适当的刻度（米，厘米，等

51、），并且标定透镜在光轴（也作为主轴被提及）上的位置。提及）上的位置。20Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing B. Draw a line LL through the center of the lens and perpendicular to the optical axis, as shown. This line will replace the actual lens surfaces that refract the light. B. .如图，画一条

52、穿过透镜中心并垂直于光轴的直线如图，画一条穿过透镜中心并垂直于光轴的直线LL。这条直线将取。这条直线将取代实际的透镜表面并可折射光线。代实际的透镜表面并可折射光线。 C. Mark the focal point F of the lens on the optical axis and locate the object on the axis, all to the same scale. (In problems of this sort, you will ordinarily be given the focal length f on the lens.) C. .在光轴上标出焦点

53、在光轴上标出焦点F，并用相同的刻度找出物体的位置。（对这类问题，并用相同的刻度找出物体的位置。（对这类问题，一般会告诉你透镜的焦距一般会告诉你透镜的焦距f）21Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing D. Draw the following rays. Any two of these rays are sufficient to locate the image, but you should always draw the third ray as a chec

54、k. D. .画接下来的光线。任意两条光线便足以定位物体的像，但你总是会画画接下来的光线。任意两条光线便足以定位物体的像，但你总是会画第三条光线来作为检验。第三条光线来作为检验。 1. Draw ray 1 parallel to the optical axis from the object to the line LL (the lens). For a converging lens, extend this ray from LL through the focal point on the side opposite the incident light. 1. .沿平行于光轴方向

55、从物体画光线沿平行于光轴方向从物体画光线1 1到直线到直线LLLL（透镜）。对于会聚透镜，（透镜）。对于会聚透镜，从从LLLL延长这条光线穿过入射光线另外一侧的焦点。延长这条光线穿过入射光线另外一侧的焦点。 For a diverging lens, extend the ray from LL as though the ray came from the focal point on the same side as the incident light. 对于发散透镜，从对于发散透镜，从LLLL延长这条光线好像光线是从入射光线一侧的焦点发出延长这条光线好像光线是从入射光线一侧的焦点发出的

56、。的。22Chapter 1. Geometrical Optics光电信息技术专业英语光电信息技术专业英语1.6 Locating Images by Ray Tracing 2. Draw ray 2 from the object to the line LL, passing through a focal point. For a converging lens, draw ray 2 through the focal point on the same side as the incident light; 从物体开始画光线从物体开始画光线2至直线至直线LL，穿过焦距。对于会聚透镜，穿过入射光线，穿过焦距。对于会聚透镜，穿过入射光线一侧的焦点画光线一侧的焦点画光线2。 for a diverging lens, draw ray 2 in the direction of the focal point on the opposite side. In both cases, continue the ray from LL parallel to the optical axis. 对于发散透