英语补充内容和习题03.ppt

1、1,English Summary,1. The electromagnetic spectrum,long,short,Wave length,380nmviolet-blue 750nmdeep-red,2,2. Law of Rectilinear propagation,Light as it advances through free space or through homogeneous, isotropic matter follows a beeline. (a direct straight course). Example: Shadows,3,3. The Law of

2、 Reflection,A light ray striking a reflecting surface and reflected from it makes equal angles with the normal to the surface at the point of incidence, and the incoming ray, the outgoing ray, and the normal to the surface at the point of intersection all lie in the same plane.,4,4. The Law of Refra

3、ction,The angle made by the incident ray, that made by the refracted ray, and the surface normal at the point of incidence in a refractive process obey the expression nsinI=nsinI The incident ray, the refracted ray, and the surface normal are all coplanar.,5,5. Total Internal Reflection,6. Fermat pr

4、inciple,Light takes the path that requires the least time.,6,7. Key words and concept,Image space extends from infinity on one side to infinity on the other. The same holds for the object space; both completely overlap. Whether a given point is in the object space or the image space depends on wheth

5、er it is part of a ray before or after refraction. If a given point is in the object space, it is a point object, otherwise it is a point image.,7,Homework,1. In ancient times the rectilinear propagation of light was used to measure the height of objects by comparing the length of their shadows with

6、 the length of the shadow of an object of known length. A staff 2m long when held erect casts a shadow 3.4 m long, while a buildings shadow is 170 m long. How tall is the building? 2. Light from a water medium with n=1.33 is incident upon a water-glass interface at an angle of 45o . The glass index

7、is 1.50. What angle does the light make with the normal in the glass?,8,Some Keywords,1. single spherical surface 2. converge and divergence 3. conjugate ( points, planes, distance etc) 4. magnification (transverse , axial , angular ) 5. Lagranges invariant 6. sign convention (vertex, image distance

8、, ) 7. image characteristics (larger or smaller, upright or inverted, real or virtual) 8. Concave and convex mirror,9,1. Vertex is the point where the optic axis intersects the surface. 2. Object distance is the distance from vertex to the object. 3. Image distance is the distance from vertex to the

9、 image. 4. Center of curvature is the center of single spherical surface. 5. Meridional plane is a plane containing the optic axis and the object.,Some Concept,10,Homework,1. A goldfish swims 10cm from the side of a spherical bowl of water of radius 20cm. Where does the fish appear to be? Does it ap

10、pear larger or smaller? 2. An object is located 2cm to the left of convex end of a glass rod which has a radius of curvature of 1cm. The index of refraction of the glass is n=1.5. Find the image distance.,11,Some Keywords and concept,1. Principal planes are defined as the loci where refraction is as

11、sumed to occur without reference as to where it actually does occur. 2. Principal points are the points where the optical axis intersects principal planes. 3. Focal points (the first, the second / the object-side , the image-side ),12,4. focal length is the distance from the principal point to the f

12、ocal point. 5. A on-axial point object at infinity and the second focal point are conjugate.,13,Some Keywords and concept,1. Graphical construction,H,H,F,F,Focal ray,Chief ray,Parallel ray,The parallel ray is first parallel to the axis and then, after refraction passes through F. The focal ray passe

13、s through F and then is rendered parallel to the axis. The chief ray goes through the principal point without deviation.,14,Some Keywords and concept,2. Newtons lens equation (x, x are called Newtons extrafocal object and image distances, respectively ) 3. Gauss equation,15,Homework,1. An object 1cm

14、 high is 30cm in front of a thin lens with a focal length of 10cm. Where is the image? Verify your answer by graphical construction of the image. 2. A lens is known to have a focal length of 30cm in air. An object is placed 50cm to the left of the lens. Locate the image.,16,Keywords and concept,1. M

15、agnification,Transverse magnification (Lateral magnification) is defined as the ratio of image size, y, to object size, y. Axial magnification (longitudinal magnification) is defined as the ratio of a short length, or depth, in the image measured along the axis, to the conjugate length in the object

16、. In the air, it is equal to the square of the transverse magnification. Angular magnification (magnifying power) The total magnification of a combination of lenses is the product of the magnification of the individual lenses.,17,Keywords and concept,2. Nodal points are where no refraction occurs. W

17、henever the refractive indices on either side of the lens are the same, the nodal points coincide with the principal points. If the refractive indices on the two sides of the lens are different, the N points would move away from the principal planes, toward the side of higher index.,18,Homework,1. T

18、he object is a transparent cube, 4mm across, placed 60cm in front of a lens of 20cm focal length. Calculate the transverse and axial magnification and describe what the image looks like?,19,Keywords and concept,1. Plane mirror wrong-reading If a mirror is rotated through a given angle, a beam reflec

19、ted by the mirror will be rotated through twice that angle.,20,Keywords and concept,2. Prisms are divided into two groups- reflecting prisms and dispersing prisms. 3. Some reflecting prisms: right-angle prisms, roof (Porro) prisms, Dove (erecting) prisms, pentagonal prisms.,21,Keywords and concept,4

20、. Dispersing prisms,Elements of a prism,Apex,Apex angle,Angle of deviation,Base,Prism equation,22,Keywords and concept,5. Dispersion Generally, the index decreases as the wavelength increases. The effect is Chromatic dispersion,23,Keywords and concept,6. Optical material (glass, crystal, plastic) Cr

21、own glass (low dispersion) Flint glass (high dispersion),24,Keywords and concept,7. Material characteristics Fraunhofer lines (blue F, yellow D, red C) Mean dispersion is numerical difference between the two refractive indices nF and nC. Dispersive power Abbes number,25,Keywords and concept,1. Stops

22、 are either the finite size of the lenses or additional diaphragms in optical system which limit the bundle of light passing through in cross section.,26,Keywords and concept,2. Theory of stops 3. An aperture stop is an opening, usually circular, in an otherwise opaque screen.,27,Keywords and concep

23、t,4. The Aperture ratio of the system is the ratio D/f. Its reciprocal is f-stop number. 5. Pupils (entrance pupil, exit pupil),28,Keywords and concept,6. A field stop, in contrast to an aperture stop, limits the angular field, or field of view. 7. Windows (entrance window, exit window) 8. Telecentr

24、ic on the object (image) side,29,Homework,1. A stop 8mm in diameter is placed halfway between an extended object and a large-diameter lens of 9cm focal length. The lens projects an image of the object onto a screen 14cm away. What is the diameter of the exit pupil?,30,2. Two lenses, a lens of 12.5cm

25、 focal length and a minus lens of unknown power, are mounted coaxially and 8 cm apart. The system is afocal, that is light entering the system parallel at one side emerges parallel at the other. If a stop 15mm in diameter is placed halfway between the lenses: 1) Where is the entrance pupil? 2) Where

26、 is the exit pupil? 3) What are their diameters?,Homework,31,Keywords and concept,1. Aberrations Monochromatic aberrations (Spherical aberration, coma, astigmatism, curvature of field, distortion) Chromatic aberrations,32,Keywords and concept,2. Monochromatic aberrations can be further divided into

27、two groups depending on whether or not they cause the image blur. Image blur occurs in spherical aberration, coma and oblique astigmatism.,33,Keywords and concept,Curvature of field and distortion cause dislocations within the image but no blur.,34,3. Wave aberration: The degree of departure from tr

28、ue sphericity,that is, the distance between the ideal reference sphere and the actual, distorted wavefront, measured along the radius of the reference sphere.,Keywords and concept,35,Homework,Answer the following questions: 1. What is an aberration? How does it come? 2. How can we classify the aberr

29、ation? 3. What is wave aberration? What relationship among wave aberration and other aberrations?,36,Homework,Reading the complementary information and fill in the following form:,37,A person wants to look at the image of his or her own eyes, without accommodation, using a concave mirror of 60cm rad

30、ius of curvature. How far must the mirror be from the eye if the person has 1) Normal vision? 2) 4diopter myopia, without correction? 3) 4diopter hyperopia, without correction?,Homework,38,Keywords and concept,1. Cross section of the human eye,39,Keywords and concept,2. Reduced eye and schematic eye

31、 3. Accommodation is accomplished by a changed of power of the lens, resulting from a change of shape.,40,Keywords and concept,4. Normal vision 5. Anomalies Myopia (nearsightedness) Hyperopia (hypermatropia, farsightedness),41,Homework,A person wants to look at the image of his or her own eyes, with

32、out accommodation, using a concave mirror of 60cm radius of curvature. How far must the mirror be from the eye if the person has 1) Normal vision? 2) 4diopter myopia, without correction? 3) 4diopter hyperopia, without correction?,42,Keywords and concept,1. Microscope,A microscope is an instrument fo

33、r viewing objects that are very small. It is a two lens system, an objective of short focal length and an eyepiece. The distance between the right-hand focus of the objective and the left-hand focus of the eyepiece is called the optical tube length.,43,Keywords and concept,2. The structure of a micr

34、oscope,44,Keywords and concept,3. Numerical aperture, NA 4. The distance of most distinct vision, 25cm in front of the eye.,45,Keywords and concept,5. Telescope Keplers telescope contains two converging lenses: an objective of long focal length and an eyepiece of short focal length. The lenses are s

35、paced so that the second focus of the first lens coincides with the first focus of the second lens.,46,Keywords and concept,Galileos telescope contains two lenses: the objective is positive and the eyepiece is negative. Still the two focal points coincide.,47,The image is seen at infinity, with acco

36、mmodation, the image is seen at the distance of most distinct vision. Instrument myopia is a phenomenon that a person involuntarily accommodates when he or she looks into an optical instrument.,Keywords and concept,48,Homework,Discussion: What differences between the following situations: 1) a micro

37、scope is used for projection; 2) the microscope is used for visual observation.,49,Supplementary materials,1. Digital camera,工作原理 颜色的形成 分色棱镜 覆盖 转轮 指标 像素数 颜色深度,50,Supplementary materials,BAYER编码,三色编码,51,Homework,Classification of camera lenses: 1)Tessar camera lens (most widely used) 2) Telephoto len

38、s 3) Wide-angle lens, fisheye lens ,sky lens 4) A zoom lens,52,Brief history of laser,The word LASER is an acronym for light amplification by stimulated emission of radiation. In 1916, Einstein predicted that the existence of equilibrium between matter and electromagnetic radiation required that bes

39、ides emission and absorption there must be a third process, now called stimulated emission.,53,This prediction attracted little attention until 1954, when Townes and coworkers developed a microwave amplifier (Maser) . In 1958, Schawlow and Townes showed that the maser principle could be extended int

40、o the visible region. In 1960, Maiman built the first laser using ruby as the active medium.,Brief history of laser,54,Compared to radiation from other sources, laser radiation stands out in several ways. It has a particular beam shape and divergence. It is highly coherent, both spatially and temporally. It is eminently suited to produce interference.,Special characteristic,55,Often it is polarized as soon as it leaves the laser