第10章-幾何光學(xué)

1、1,幾何光學(xué)是以光的直線傳播性質(zhì)為基礎(chǔ)，研究光在透明介質(zhì)中傳播規(guī)律的學(xué)科。,幾何光學(xué)的理論基礎(chǔ),Chapter 10 Geometrical Optics,2,Section 1. Refraction at a Spherical Surface,Section 2. The lens,Section 3. The eye,Section 4. The Magnifier and Microscope,Section 5.

2、 The Special Microscope and Fiberscopes,,Chapter 10 Geometrical Optics,3,1 . Refraction at a Spherical Surface,2 . Coaxial System,,Section 1. Refraction at a Spherical Surface,4,system,law,球面折射系統(tǒng),,1.Refraction at a sph

3、erical surface,Object distance,Image distance,refractive index,radius of curvature,5,,Paraxial condition, i1 i2,analyze,球面折射系統(tǒng),,1.Refraction at a Spherical Surface,,,6,,,?,?,discuss,Condition：,Paraxial beam,We adopt

4、the following rules：,1、When the object is on the same side of the refracting surface as the incoming light ,the object distance u is positive ;otherwise it is negative.,球面折射系統(tǒng),,1.Refraction at a Spherical Surface,2、When

5、 the image is on the same side of the refracting surface as the outgoing light ,the image distance v is positive ;otherwise it is negative.,7,,1.Refraction at a spherical surface,3、When the center of curvature C is on t

6、he same side as the outgoing light ,the radius of curvature is positive ;otherwise it is negative.,,,?,,Dioptric power,(D),R: meters,A quantity of describing the ability of refraction For the refractive system : ?(

7、diopter),8,,1.Refraction at a Spherical Surface,9,secondary focal point,F2,球面折射系統(tǒng),,10,focus,Primary focal point,Primary focal length,Secondary focal point,Secondary focal length,Image is at the infinity,Object is at th

8、e infinity,Focal degree,,球面折射系統(tǒng),,(diopter--D),11,System,If a optical system is made up of many refractive spherical surface ，and all the center of curvature of refractive surface is on a line ，then we call the syste

9、m is coaxial system .The line which joins all the center of curvature is called principal optic axis .,球面折射系統(tǒng),,2 . Coaxial system,12,2 . Coaxial system,,Applying the methods of single spherical refraction in turn,the ob

10、ject,for the second surface being the image formed by the first.,13,Analyze,光線經(jīng)前一個折射面所成的像，是下一個折射面的物，對于系統(tǒng)中的多個折射面，如此依次成像，即可得到最后的像。,,Attention,?,?,前一像作為下一折射面的物時(shí)，是實(shí)物(real object )還是虛物(virtual object),仍對近軸光線成立,球面折射系統(tǒng),,2 . Coa

11、xial system,14,Example,A glass ball(n=1.5)which diameters is 20cm .A object is put at the place of 40cm before the sphere .Where is the image ?,To the first refractive surface,,n1＝1.0，n2＝1.5，u1＝40cm，r＝10cm，,,＝60cm,15,To

12、 the second refractive surface,u2＝－（60-20）＝－40cm，n1＝1.5，n2＝1.0，r＝－10cm，,,＝11.4cm,16,1. The Thin --lens Equation,2. The Combination of the thin lens,3 . The Thick lens,4 . The cylindrical lens,5 . Lens Aberrations,Sec

13、tion 2 The lens,,17,Lens,Be made up of two coaxial refractive surfaceIncluding(converging lens and diverging lens),Two refractive surface are all spherical surfaces ,or one is spherical surface ,another one is plane。,Th

14、e distance on the optic axis between the two refractive surface is lens thickness,,Thin lens,The lens thickness is negligible in comparison with the object distance and the image distance,Thick lens,薄透鏡,,1. The th

15、in -lens Equation,18,1). The lines through the center of the lens don’t change direction .,2) . The parallel light lays with the axis pass through the focal point after refraction；,3). The light rays through focal

16、 point is parallel with the Axis after refraction。,,,薄透鏡,,Basic imaging law about thin lens,,19,,可得,薄透鏡,,Form,Imaging equation about thin lens,,20,To the first refractive surface,To the second refractive surface,,,薄透鏡

17、,,21,,,,n1,n2,薄透鏡,,,Gauss Equation about thin-lens,,22,Focal length,?,?,n1 = 1 , in the air n represents the refractive index of the material of thin lens , then the focal length,Sign convention：,凸球面對著入射光線，r取正號,凹球面

18、對著入射光線，r取負(fù)號,薄透鏡,,Principal quantity about thin lens,,23,Converging lens,Diverging lens,r1 > 0,r2 < 0,f > 0,r1 < 0,r2 > 0,f < 0,薄透鏡,,24,Dioptric power,?,?,表示透鏡的折光本領(lǐng),unit：diopter (屈光度）,通常所說的眼鏡的度數(shù)等于屈光度的1/

19、100倍,1屈光度 = 100度,D越大，系統(tǒng)的折光能力越強(qiáng),薄透鏡,,25,. 單向放大率 （復(fù)習(xí)內(nèi)容）,又叫長度放大率,,,薄透鏡,,(lateral magnification),26,Example 10-3,,,,,p191,(板書講),27,The coaxial system is made up of two or more thin lens 。,Definitions,Construct,Imaging in tu

20、rn,Equation,薄透鏡,,2 . The combination of thin lens,28,To the first lens,To the second lens,,,薄透鏡,,29,Example 10-4 (重點(diǎn)),(板書講),,p192,30,3、 Thick Lens,1）. Concept of thick lens,2）. Imaging law,,31,,The term thick lens

21、means either a single lens whose thickness is not negligible in comparison with the object distance and the image distance ,or any combination of lens such as a corrected camera lens.,Thick lens,1）. Concept,Thin lens

22、,,32,對每一個單球面，依次應(yīng)用單球面系統(tǒng)的成像規(guī)律；,利用共軸系統(tǒng)的基點(diǎn)概念——把透鏡看做是一個體系，定義這個系統(tǒng)的三對基點(diǎn)，只要知道這三對基點(diǎn)的位置，就可以用作圖法解決成像問題;,Thick lens,方法一,方法二 *,計(jì)算法解決一些成像問題。--Imaging equation,方法三,,2）. Imaging law,33,a). Two focal point,調(diào)整光源在主光軸上的位置，使其光束通過厚透鏡后變?yōu)槠叫泄?，這時(shí)

23、點(diǎn)光源所在的位置就稱為共軸系統(tǒng)的第一主焦點(diǎn)F1。,平行于主光軸的光束，通過系統(tǒng)折射后與主光軸相交于一點(diǎn)，稱為共軸系統(tǒng)的第二主焦點(diǎn)F2。,The primary principal focal point,F1,,The secondary principal focal point,,F2,Thick lens,,34,b) . Two principal points,通過F1的入射光線的延長線與出射光線的反向延長線交于A1點(diǎn)，過A

24、1點(diǎn)所做的垂直于主光軸的平面稱為共軸系統(tǒng)的第一主平面，第一主平面與光軸的交點(diǎn)H1就稱為共軸系統(tǒng)的第一主點(diǎn)。,平行于主光軸的入射光線與其射出線的反向延長線的交點(diǎn)，決定了系統(tǒng)的第二主平面，第二主點(diǎn)。,,,,,,,,H2,Thick lens,,35,不管光線在厚透鏡中經(jīng)過怎樣曲析的路徑，在效果上可以看作只在主平面上發(fā)生折射。,通過一個主平面上任一點(diǎn)的光線，一定通過另一主平面上的對應(yīng)點(diǎn)。,,,,,Thick lens,,Two princip

25、al points,36,c). Two nodal points,There are another two points N1 and N2 ,called nodal points which are similar as the optical center of thin lens that rays pass through them without deviated as in next fig. Here QN1

26、 is parallel to Q'N2.,Thick lens,,37,方法二 厚透鏡的基點(diǎn)作圖法,通過第一主焦點(diǎn)的光線在第一主平面上折射后平行主光軸射出；,平行于主光軸的光線在第二主平面折射后，通過第二主焦點(diǎn)；,通過第一節(jié)點(diǎn)的光線從第二節(jié)點(diǎn)平行于入射方向射出。,?,?,?,Thick lens,,38,1.A ray parallel to the axis is refracted by the second pri

27、ncipal,plane and passes through the second focal point of a thick lens.,2.A ray through the first focal point is refracted by the first principal,plane and emerges parallel to the axis.,3.A ray through the first nodal p

28、oint of the thick lens ,after,,refraction by the lens ,is not deviated and emerges from the,second nodal point.,39,都是以主點(diǎn)為基準(zhǔn),物距、像距和焦距,Thick lens,厚透鏡的成像公式,,40,若系統(tǒng)的最初和最后媒質(zhì)相同，則 f1 = f2 =f，N1與H1重合，N2與H2重合，且有成像公式：,Thick lens,

29、厚透鏡的成像公式,,41,,,,If the refractive surface of lens is portion of the cylinder ,we call the lens is column lens .,4. Cylindrical lens,,42,,,,水平光束入射后會聚（發(fā)散）,在豎直方向上光線不改變方向,點(diǎn)狀的物經(jīng)圓柱透鏡折射后成為線狀的像,,,Astigmatism,43,5、Lens Aberrati

30、ons,,Spherical aberration（球面像差—球差）,Chromatic aberration（色像差）,44,1 . The essential parts of the eye and accommodation,2 . Defects of vision and correction,Section 3 The Eye,,45,角膜(cornea) 虹膜(iris) 瞳孔(pupil) 網(wǎng)膜(retina

31、) 黃斑(yellow spot) 水狀液 玻璃狀液 眼球剖面圖,eye,,1 . The essential parts of the eye and accommodation,46,從光學(xué)的觀點(diǎn)來看，眼睛是一個由多種介質(zhì)組成的折射系統(tǒng)。眼內(nèi)各種不同介質(zhì)對光線具有不同的折射作用，進(jìn)入眼睛的光線，經(jīng)多次折射后，才成像在視網(wǎng)膜上。,把眼睛看做是由多種均勻介質(zhì)組成的共軸球面折射系統(tǒng)。,根椐古氏（Gullstrand）的計(jì)算，這一系統(tǒng)的光

32、學(xué)性質(zhì)大概有書中表11-2所給的平均數(shù)值。,1).古氏平均眼,眼睛,,a. Optic characters of the eye,47,角膜與空氣的折射率相差最大，且角膜的曲率半徑最?。s為5mm），因此，角膜的折射本領(lǐng)最大，它對進(jìn)入眼中的光線起主要的折射作用。,2) . 簡約眼(reduced eye),生理學(xué)上常常把眼睛簡化為單球面折射系統(tǒng)，叫做簡約眼(reduced eye)。,eye,,a. Optic characters

33、 of the eye,48,3) . 眼睛的調(diào)節(jié)(accommodation),眼睛之所以能夠看清遠(yuǎn)近不同的物體，是由于眼的焦度可以在一定范圍內(nèi)改變,Far point： 正常人在無窮遠(yuǎn),Near point ：正常人在10~12cm,Distance of distinct vision: 正常人為25cm,eye,,調(diào)節(jié)(accommodation)－眼睛改變焦度的過程叫調(diào)節(jié).,49,Visual acuity：,,Th

34、e eyes can distinguish the least visual angle,從物體兩端射到眼中節(jié)點(diǎn)的光線所夾的角度,0.1 0.2 0.3 …… 1.0 1.2 1.5,10? 5 ? 3.3 ? …… 1.0 ? 0.8 ? 0.67 ?,eye,b.Visual angle：,,50,51,2) . Myopic eye,1). Normal eye,3). Hyper

35、opic eye,eye,,2 . Vision Defects of vision and correction,52,,2) Myopia eye,The function of lens is to form a virtual image on the far point of the myopia eye .,Example11-5,53,3),Hyperopic eye,The function of lens is

36、 to move the object,farther away from the eye to a point where a sharp retinal image can be formed.,54,4) Astigmatism eye,角膜表面的曲率半徑不一致，不是球面，光線經(jīng)過眼球的不同經(jīng)線后就不可能會聚于同一焦點(diǎn)，在網(wǎng)膜上不能形成清晰的像。,矯正方法是配適當(dāng)?shù)膱A柱透鏡。,?,老花眼不屬于屈光不正，是隨著晶狀體調(diào)節(jié)機(jī)能減

37、退出現(xiàn)的近點(diǎn)遠(yuǎn)移的現(xiàn)象，補(bǔ)救的辦法是在看近物時(shí)戴適當(dāng)?shù)耐雇哥R。,eye,,55,Eg1:The near point of a certain eye is 100 cm in front of the eye .what lens should be used to see clearly an object at the normal reading distance ?,v = －100cm = －1m,Solution:,56

38、,Eg.2 The far point of a myopia eye is 0.4m in front of the eye ，what lens should be used to see clearly the object at infinity ?,,v = －0.4m,,,Solution:,57,. Magnifier,Section 4 Magnifier,,58,Magnifier,1) The apparent s

39、ize of an object is determined by the size of its retinal image .which ,in turn ,if the eye is unaided ,depends upon the angle subtended by the object at the eye.,2) When one wishes to examine a small object in detail, o

40、ne brings it close to the eye in order that the angle subtended and the retinal image may be as large as possible.,59,Magnifier,magnifier,,3) Since the eye cannot focus sharply on objects closer than the near point . by

41、placing a converging lens in front of the eye ,the accommodation may ,in effect ,be increased . The object may then be brought closer to the eye than the near point and will subtend a correspondingly larger angle. A lens

42、 used for this purpose is called a magnifier. The lens forms a virtual image of the object.,60,.Magnifier,y,y,magnifier,角放大率:The angular magnification,,At normal reading distance,( f in cm),61,In order to see clearly

43、 a small object that can not be seen clearly using one’s unaided eye . When an angular magnification higher than that attainable with a simple magnifier is desired ,it is necessary to use a compound microscop

44、e ,usually called merely a microscope .,Section 5 Microscope,62,. The essential elements of microscope,Section 5 Microscope,. Overall magnification of the microscope,. The resolving power of microscope,. A few special

45、 biological and medical microscopes,,63,,,,ocular L2,Objective L1,microscope,,. The essential elements of microscope,64,. The overall magnification of microscope,y,y1,,The lateral magnification m of objective,The angul

46、ar magnification? Of ocular,microscope,65,66,. The resolving power of microscope,67,. The resolving power of microscope,68,顯微鏡的分辨本領(lǐng)The resolving power of microscope,69,The least distinguished distance of optics syst

47、em,. The resolving power of microscope,物鏡的數(shù)值孔徑,methods of increasing The resolving power of microscope,紫外顯微鏡,熒光顯微鏡,電子顯微鏡,Increasing the numerical aperture,The space between the object And the objective is filled wit

48、h an oil,,,The resolving power 1/z decided only by the objective,microscope,,Decreasing the light wavelength,,70,71,72,1 . 偏光顯微鏡（polarizing microscopes),以可見光的偏振特性對具有雙折射現(xiàn)象和旋光性,,的物質(zhì)進(jìn)行研究鑒定的必備設(shè)備。,4 ?,10 ?,25 ?,40 ?,5 ?,10

49、 ?,16?,2 . 電子顯微鏡(electronic microscopes),用波長很短的電子射線代替可見光做成的。(80-100萬倍）（0.144納米）,microscope,,. A few special biological and medical microscopes,73,4 . 熒光顯微鏡,有些物質(zhì)（維生素A、核黃素、硫胺素等）受紫外線照射能發(fā)出熒光，還有些物質(zhì)（細(xì)菌）可以用熒光染料給其染色。,靈敏度高,用紫外線