应用光学 英文版 chapter 3.ppt

1、Chapter 3 Instruments for Human Eyes,Retina: 视网膜 Pupil: 瞳孔 Diopter: 视度 Visual acuity/Resolution: 分辨率 Myopia: 近视眼 Hyperopia: 远视眼,Instruments for Human Eyes ： magnifier, microscope and telescope,function：improve our vision ability,For a visual optical system: the human eye is the receiver of the syste

2、m.,3.1 Characteristics of the Eye,3.1.1、structure of the eye:,Eyes camera,Pupil(瞳孔) stop(光阑),Lens of eyecamera lens,Retina(视网膜) film(底片),lens,3.1.2 the Accommodation of the Eye,Eye , two kinds of accommodation functions： diopter accommodation and pupil accommodation,(1) Diopter accommodation,For a n

3、ormal relaxed eye: the infinite object images on the retina (视网膜).,The second focal point of the eye: retina,The eye muscles are most relaxed when the eye is looking at distant objects (“at infinity”).,the unit : Diopter/屈光度，视度,from the eye to the object plane. unit：m/meter,Ex.：object，,then,When at

4、infinity，,Measuring for the accommodation degree of the eye:,Near point/近点: a closest point at which the eye can see an object.,The least distinct distance or near point distance/近点距离,Far point/远点:,The far point distance/远点距离: the longest distance which the eye can see clearly.,SD Near point SD Far

5、point,For a normal eye:,The maximum accommodation range of the eye:,SD Near point SD infinity,Far point/远点: at infinity,The maximum accommodation range of the eye is restricted by ages.,(2) Pupil accommodation,2mm 8mm,3.1.3 visual Acuity,For two points,For lines,3.2 principles of Magnifier and Micro

6、scope,Magnifying power of the instrument（视放大率） :,The eye request visual instruments :,(1) Enlarge ,(2) output rays are parallel, or the image of the instrument should be at infinity,思考： 0或0说明什么？,3.2.1 The Magnifier,the normal reading distance/明视距离,2. The virtual image of Magnifier is at 250mm,Discus

7、sion:,Discussion:,3. A magnifier usually consists of a single lens,3.2.2 The Microscope,Structure：objective(物镜)+ eyepiece(目镜),思考：比较显微镜和放大镜的异同？,P186,The resolution of a microscope:,the smallest separation between two object points:,NA= nsinU numerical aperture of the system,Note that the index n and

8、the slope of the marginal ray U are those at the object .,Example： If the aiming precision of a reading microscope is 0.001mm,The angle when viewing an object of 0.001mm directly is,Solution:,Using,If we use a eyepiece, then the objective:,3.3 principle of Telescope,Structure: objective + eyepiece,T

9、hree types of telescopes: Kepler Telescope, Galilean Telescope, The erecting（正立） Telescope,1. Types of telescopes,a) Kepler Telescope:,Positive objective + Positive eyepiece,inverted real image,Application: Astronomical telescopes,We can add a reticule on the internal image plane for aiming and meas

10、uring.,b) Galilean Telescope:,Positive objective + negative eyepiece,erect virtual image,Application: watching operas,c) The erecting（正立） Telescope:,Erector: lens, or prism,erect real image,Application: military telescopes,Prism Erecting Telescope,Discussion:,The angular magnification, lateral magni

11、fication, axial magnification are all independent of the position of the conjugate planes.,Example 1, If we want to discern a 200mm interval at the distance of 5kilometers, =？,solution：,By the naked eye，,a telescope：,solution：,then：,the angular error in the image space：,the aiming angular error :,Ex

12、ample 2. If a theodolite telescope, If using the method of alignment of two strait lines, what is the aiming angular error?,2. the angular resolution of a telescope (in object space):,In air,P184-185,Dthe diameter of a telescope, unit: mm,3.4 Defect of Eyes and Diopter Accommodation of Optical Instr

13、uments,1. Myopia and Hyperopia,For a normal eye:,The far point is at infinity,A nearsighted eye/myopia(近视眼)： F falls ahead of the retina.,farsightedness/hyperopia(远视）: F falls behind of the retina.,For example, a nearsighted eye,The myopic degree is often expressed by the diopter of its far point di

14、stance.,A nearsighted eye/myopia(近视眼)：,(SD=-2+(-4)=-6),the normal reading distance:-16.7mm,the near point distance with -10D accommodation:,Example, with +2 diopters of hyperopia and -10D of accommodation range. Then ,Farsightedness/Hyperopia(远视）:,A hyperopic person can possibly see the infinite obj

15、ect. But the near point distance will be increased.,myopia(近视): a negative lens,Correcting the defect of eyes by the lens:,Hyperopia(远视): a positive lens,Normal eye,2. Diopter Accommodation of Optical Instruments,问：近视眼和远视眼使用望远镜，目镜应分别往哪边移动？,The moving amount of the eyepiece,If the required diopter of the instrument is SD，,which means the image distance is：,The moving amount of the eyepiece:,问: 目镜该往哪边移动？如果 呢？,solution：,The moving amount of the eyepiece is 2mm.,Review of chapter 3,1. Structure of eye,2. Instruments for eyes,To enl