English summary.ppt

1、1,English Summary,1. The electromagnetic spectrum,long,short,Wave length,380nmviolet-blue 780nmdeep-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,normal,Incid

4、ent ray,Refracted ray,Denser medium,Rarer medium,Critical angle,Surface,6,6. Fermat principle,Light takes the path that requires the least time.,7,7. 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 ove

5、rlap. Whether a given point is in the object space or the image space depends on whether 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.,8,Key words and Concept,The index of refraction, or refractive index,

6、 of any optical medium is defined as the ratio between the speed of light in a vacuum and the speed of light in the medium. Optical path The principle of Reversibility,9,Homework,1. In ancient times the rectilinear propagation of light was used to measure the height of objects by comparing the lengt

7、h of their shadows with 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

8、 45o . The glass index is 1.50. What angle does the light make with the normal in the glass? P12 4&9 (P13 4&15),10,Some Keywords and concept,1. Principal planes are defined as the loci where refraction is assumed to occur without reference as to where it actually does occur. 2. Principal points are

9、the points where the optical axis intersects principal planes. 3. Focal points (the first, the second / the object-side , the image-side ),11,4. Focal length is the distance from the principal point to the focal point. 5. An on-axial point object at infinity and the second focal point are conjugate.

10、 P36-1 (P37-1),12,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 passes through F and then is rendered parallel to the axis. The chief ray goes thro

11、ugh the principal point without deviation.,13,Some Keywords and concept,2. Newtons lens equation (x, x are called Newtons extrafocal object and image distances, respectively ) 3. Gauss equation,14,Keywords and concept,4. Magnification,Transverse magnification (Lateral magnification) is defined as th

12、e 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. In the air, it is equal to the square of the transverse magnification. Angul

13、ar magnification (magnifying power) The total magnification of a combination of lenses is the product of the magnification of the individual lenses.,15,Keywords and concept,5. Nodal points are where no refraction occurs. Whenever the refractive indices on either side of the lens are the same, the no

14、dal 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.,16,Homework,1. The object is a transparent cube, 4mm across, placed 60cm in front of a lens of

15、 20cm focal length. Calculate the transverse and axial magnification and describe what the image looks like? P36-3&4 (P37-3&4),17,Keywords and concept,1. Lens is a combination of two surfaces that enclose a medium of a refractive index different from that outside the surfaces.,18,Keywords and concep

16、t,2. Types of lenses,Converging or positive / Diverging or negative lenses Biconvex / Plano-convex / positive meniscus lens Biconcave / Plano-concave / Negative meniscus lens,19,Keywords and concept,1. Stops are either the finite size of the lenses or additional diaphragms in optical system which li

17、mit the bundle of light passing through in cross section.,20,Keywords and concept,2. Theory of stops (This theory is discussing about light limitation and proper diameter of optical elements in an optical system. ) 3. An aperture stop is an opening, usually circular, in an otherwise opaque screen.,2

18、1,Keywords and concept,4. The Aperture ratio of the system is the ratio D/f. Its reciprocal is f-stop number. 5. Pupils (entrance pupil, exit pupil),22,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

19、 window) 8. Telecentric on the object (image) side,23,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?,24,2. Two len

20、ses, a lens of 12.5cm 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 ent

21、rance pupil? 2) Where is the exit pupil? 3) What are their diameters?,Homework,25,Homework Answer,1. What is an aberration? How does it come? An aberration is the difference between the real image and the ideal image. In paraxial-ray tracing, which we discussed earlier in conjunction with single sur

22、faces and thin lenses, we had assumed that the angles which the rays subtend with the optic axis are,26,small. If this is so, the sines of these angles can be set equal to the angles themselves( in radians). In fact, the angles are larger, and if we use exact ray tracing, this can no longer be done.

23、 The sine of an angle must then be represented by a series expansion. So the difference occurs.,27,Homework Answer,2. How can we classify the aberration?,28,Homework Answer,3. What is wave aberration? What relationship among wave aberration and other aberrations? The degree of departure from true sp

24、hericity, that is, the distance between the ideal reference sphere and the actual, distorted wavefront, measured along the radius of the reference sphere.,29,Generally speaking, the larger geometrical aberration is, the larger wave aberration is. Spherical aberration,coma, and astigmatism all have c

25、haracteristic wavefront distortions. In curvature of field and distortion, the wavefront normals come together but at the wrong point.,30,Homework answer,Fill in the following form.,31,Keywords and concept,1. Aberrations Monochromatic aberrations (Spherical aberration, coma, astigmatism, curvature o

26、f field, distortion) Chromatic aberrations (Longitudinal, Lateral ),32,Keywords and concept,2. Monochromatic aberrations can be further divided into two groups depending on whether or not they cause the image blur. Image blur occurs in spherical aberration, coma and oblique astigmatism. Curvature of

27、 field and distortion cause dislocations within the image but no blur.,33,3. Wave aberration: The degree of departure from true 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 con

28、cept,34,Homework,Answer the following questions: 1. What is an aberration? How does it come? 2. How can we classify the aberration? 3. What is wave aberration? What relationship among wave aberration and other aberrations?,35,各种像差的定义、影响因素、性质、消像差方法？,36,Keywords and concept,1. Cross section of the human eye