(光电信息工程专业英语)专业英语第七讲Geometrical-Optics课件

1、光电信息工程专业英语Chapter 2 Geometrical Optics光电信息工程专业英语Chapter 2 Geometrica1.6 Locating Images by Ray Tracing8 . 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 changes, the ray is displaced later

2、ally. 翻译： 一个普通的平面玻璃，例如带有两个平行面的玻璃窗，透过光线而不改变它的方向。虽然方向不改变，但光线会发生侧移。1.6 Locating Images by Ray Tra1.6 Locating Images by Ray TracingThe 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)

3、.9. 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 originate.翻译：任何一种情况下，在来自物的光线相交的位置形成图像（实），或在看起来发出光线的点形成图像（虚）。1.6 Locating Images by Ray Tra(光电信息工程专业英语)专业英语第七讲Geometrical-Optics课件(光电信息工程专

4、业英语)专业英语第七讲Geometrical-Optics课件1.7 The Thin-lens Equation1. In the predceding derivation, we examined the special case of a converging lens with the object placed outside the focal point. However, the thin-lens equation holds for both converging and diverging thin lenses and for any object distance,

5、 provided the following sign conventions are maintained.词汇：Preceding在前的，前述的Hold 有效Sign convention 符号规则Maintain 维持，供养，继续，主张参考翻译：在上述的推导中，我们检验了物在会聚透镜焦点以外的特殊情况。然而，如果遵守下述的符号规则，薄透镜公式对于会聚和发散薄透镜都是有效的，且不论物体远近。Provided,conj.假如，倘若：Provided (that) there is no opposition, she will be our new chairman. vt.提供；给予（p

6、rovide的过去式） A lens whose thickness is small in comparison with its focal length is called a thin lens.1.7 The Thin-lens Equation1. I1.8 Spherical Mirrors2. A concave mirror reflects light from the inner surface of a sphere; a convex mirror reflects light from the outer surface.1.8 Spherical Mirrors2

7、. A conc3. However, if the diameter of the incident beam is a large fraction of the diameter of the mirror, the reflected rays do not all converge to the same point, and the image is somewhat blurred. This effect, called spherical aberration, is discussed in more detail in section 1.9.1.8 Spherical

8、Mirrors3. However, if the diameter of1.9 Lens Aberrations4. Up to now, our discussion of lenses has not taken into account some of the optical imperfections that are inherent in single lenses made of uniform material with spherical surfaces. These failures of a lens to give a perfect image are known

9、 as aberrations. 句子结构：our discussion has not taken into account imperfections其它句子成分：optical imperfections that are inherent in single lensessingle lenses made of uniform material with spherical surfaces翻译：迄今为止，我们对透镜的讨论还没有考虑由均质材料组成的具有球面的单透镜固有的光学缺陷。这些透镜缺陷就是像差.1.9 Lens Aberrations4. Up to nAberrations像

10、差：使像模糊：球差：Sperical aberration慧差：coma aberration像散： astigmatism 使像变形：场曲：field curvature畸变：distortion色差：chromatic aberration参考：1./article-1584.html2./wiki/%E8%B1%A1%E5%B7%AEAberrations像差：5. We see that what we said earlier about thin lenses is strictly true only in the so-called paraxial approximation

11、-that is, only for incoming rays that are not far from axis and that are parallel to the axis. These limitations explain why the center of an image is often relatively clear while the edges are considerably more distorted.句子结构：We see that句子其它成分：what we said is trueparaxial approximation-that is, onl

12、y for incoming rays that are not far from axis and that are parallel to the axis.参考翻译：我们发现，只有在所谓的傍轴近似条件下，我们先前关于薄透镜（的公式）才是严格正确的也就是说，只有当入射光线离光轴较近，且平行于光轴时才成立。这些限制解释了为什么图像常常中央相对清晰而边缘会有较大的变形。1.9 Lens Aberrations5. We see that what we said ea6.However, to reduce aberrations of this kind to an acceptable l

13、evel for optical instruments such as microscopes, binoculars, or cameras, each lens must be made of several thin lenses in combination. 参考翻译1：然而，为了减小这种由于光学仪器所带来的在允许之内的像差，例如显微镜，双筒望远镜，或者照相机，每一个镜头必须由几个混合的薄透镜组成。参考翻译2：然而，为了使光学光学仪器（例如显微镜，双筒望远镜，或者照相机）的像差减少至可接受的程度，每一个镜头必须由几个薄透镜组合构成。几个要点：reduceto an acceptab

14、le levelseveral thin lenses in combination1.9 Lens Aberrations6.However, to reduce aberratio7.Along with the aberrations mentioned above, there is an additional complication: the index of refraction varies slightly for light of different colors that is, different wavelengths. This variation is most

15、easily seen in the action of a prism. along with和一起，同一道参考翻译：与上面提到的像差一起的，另外还有一个复杂情况：（同一种材料）折射率对不同颜色的光有微小的差别，也就是说对不同波长，折射率是不同的。这种差异在棱镜中最容易看到。1.9 Lens Aberrations7.Along with the aberrations m8. Chromatic aberration can be troublesome in any optical instrument that uses lenses. To overcome this problem

16、 in telescopes, Isaac Newton invented the reflecting telescope, which uses a focusing mirror instead of an objective lens. No dispersion occurs when light is reflected from the mirror, so chromatic aberration is eliminated from that element.牛顿1672年使用的6英寸反射式望远镜复制品，为皇家学会所拥有。 1994年，不列颠哥伦比亚大学开始建造一台口径为6米

17、的旋转水银面望远镜大型天顶望远镜（LZT），并于2003年建成1.9 Lens Aberrations8. Chromatic aberration can be9. By choosing materials with indices of refraction that depend in different ways on the color of the light, lens designers can ensure that positive and negative lens elements compensate for each other by having equal b

18、ut opposite chromatic effects.参考翻译1：对不同折射率材料的选择依靠光线在不同方式中的颜色，透镜设计者可以通过使正负透镜相等但有相反的色效益来确保正负透镜相补偿。参考翻译2：不同颜色的光会被沿不同路径折射，通过选择不同折射率的材料，透镜设计者可以确保正透镜和负透镜单元具有相反的色差效应，从而（使色差）相互补偿。1.9 Lens Aberrations9. By choosing materials with aberrationThe blurring in the first photograph is primarily the result of spheraical aberration, and the inaccuracy in the color is due to chromatic aberration. A color photograph thaken through the well-corrected lens (second figure) shows no visible color errors.aberrationThe blurring in the Aspherics lensAspherics lens名词复数medium media