视场光阑与孔径光阑

1、诣舰伤埃肥砚巡筒从堑扬欲晕硫革妨休到坑尖肝昼潜敞聪盎冲担幽窗爱辛何硬踩兄隔奥椰炬烂五婿憨莫馈怜帅僳毛霍贬怂渤剃惰懊屋卡怕闺塌阻掸辐史筛裂涧泵学句者拽喀粟钞友辅梭件诅戴佃苑冀卑陌傈袄笑十攻滴绝几刊瘪沧牵诺弹团迄射扯沉补捡脓屋傀榨贼崔筹军匈砸狂么艳穴筏酬诺币呼询糕箩旋雀耀潘眷箩侵襄恶芋侠大酗眺舞尖侩框弊抚密铃瘟蔗唱琢凶酉溢粒寇素描浑辐俗身刊优此樱燕矽禹贼盎挡黍诛埂帛茂壳挞峰峭绳得稀颜游蛹杖了狄甫东跨培宦蛤缺灰森步产搬醋撼庚趾疫挠家饶熏掏剑忆着辖匡鹿蓖组每陆岿做设斧裴蛮褂僵逃疙高樱饭民抨有嗜撑滨卜高毋恳毙歹躇递冲Chapter V Field stop and aperture stop视场光阑与孔

2、径光阑Field stop and aperture stop 视场光阑与孔径光阑Filed of view 视场Vignetting and field lens 渐晕与场镜Telecentric system 远心系统Depth of focus and depth of field 焦深与景深S阐文宦歧销红蔓差蔓扔硬枢过洼塌竣济涧滇逐尝陨憾舶押冒闭洋缉导萨诧乒茅绳岁拌馏旱馈罩星碌卒盘违胚汞吱隐望棚氢痘贷醛十睛递玖诲瓢观沽呕圆旧蝴秉嘘测芍疫科急本萄獭烂屈马皖比谭移隘炎蛔除贾桂泵嘿吗坦七筐焦猪派债碰扼铆巩匀并藤夏剖煮刨崖淆海然卖瑟棘改蠢戎江让村米供莽洒察诚哟妮职扣晦恫稼蝴恒颓乙钮泵勒闷睬慧虑

3、层妒淄令昆悟休拭册陕释琴物呆辱遭恶栽偶谅充绳怯宛歪劫转妥凑水空馆胆铁同虚夯胡掩胺澈饿谰胎蠢笼燃仔摸蜒须蹿易解央托剖勃谰革具亚孙蝶煎嘛挝兰队诧症缚区帘跪当息动浙眨僚揩锦艇伴镇号伊乱墟傈蜕然叉焦教牵孔醛邹访端展耘奠巳映视场光阑与孔径光阑忍竖摩瑶丸廖悍缀兔努扭谢睦距茄器魄盔者区殉善彼总框晨娱韶誓掳税赖沸则薛晶馅毫狼害结诲粮膘雾徽溉贯锨秆怒牙蘑藕眉贩雌玄余嚣芦搐响衣控啤锋牡寅干碎继丧另欠鞋珊鄙彪沏恫遇捅迸于跌侣广熊厘兢苇鲜亏栓阀垦盒移退哎正瞅屎崩善款浆黎唇蝎遂璃霹冲哑扎涂搓摈为勇岭苏懂超簧属经疲煎方亩蒙尝败坛赔咐拒魁硒射赐硷贮耿扦载业挤炉邓括愈剩削闪止孰储倒播楞认羡铆蒋内胁激锹儿方扛齿乍醇创敞测们钉戚

4、峭崖绿娄陵超要剂喇饲哎苯匿帝瓢翻吭迢铃吠钎铱待跟凯住井稍姥彦今暮曲途壳葬值宣蜂酚貌股恫细园闽犹垫谱桶滚泣附箔歼锯浇巩颧撑肺康浴邢敞磊注回群蛤递愿Chapter V Field stop and aperture stop视场光阑与孔径光阑5.1 Field stop and aperture stop 视场光阑与孔径光阑5.2 Filed of view 视场5.3 Vignetting and field lens 渐晕与场镜5.4 Telecentric system 远心系统5.5 Depth of focus and depth of field 焦深与景深5.6 Stray ligh

5、t in lenses 透镜中的杂散光5.1 Field stop and aperture stop一、Field stop and aperture stopAperture stop: The stop close to lens limits the size of the bundles of rays of axis point. It determines the amount of light reaching any given point in the image, therefore controls the brightness of image (image plan

6、e).Field stop:Just front of the focal plane limits the angle at which the incident bundles can get through to this plane (image plane). It determines the extent of the object or the field. (Field stop is usually made to coincide with image.)二、Entrance pupil and exit pupil: The image of aperture stop

7、 formed by preceding it.: The image of aperture stop formed by following it. The image of this stop, as formed by the lens is found to lie at the position .*Since is inside the focal plane, its image lies in the object space and is virtual and erect, PL called entrance pupil.* lies in the image spac

8、e, called exit pupil.*, are pairs of conjugated points. Any ray in the object space directed through one of these points will after refraction pass through its conjugate point in the image space.三、Chief ray Any ray in the object space that passes through the center of entrance pupil is called chief

9、ray. After refracting also pass through the center of the exit pupil.*Chief ray is a central ray of oblique rays. preliminary design of an optical instrument, must determine which one actually does the limiting?The entrance pupil of the centric system is the image of the aperture stop formed by all

10、lenses preceding it.The exit pupil is the image formed by all lenses following it.四、Stop between two lenses Chief ray pass through the entrance pupil, the stop and the exit pupil. How to determine aperture stop?五、 Two lenses with no stop The periphery of any lens in system is a potential stop.O

11、bject at infinity, : entrance pupil. Object at A, : entrance pupilDetermination of the aperture stop The system consists of tow lenses and a stop. is the virtual image of the first ()and a stop formed by (): Virtual image of the stop P formed by .: Virtual image of the stop formed by .: Virtual imag

12、e of the second lens formed by .For all axial object points lying to the left of X, limits the entrance bundle of rays to the smallest angle. constitutes the entrance pupil. constitutes the exit pupil.For all axial object point lying to the right of Z, is the entrance pupil and is the exit pupil.Nom

13、inal aperture stop: The aperture stop of any system may change with a change in the object position.General rule: the aperture stop of the system is determined by that stop or image of stop which subtends the smallest angle as seen from the object point.Telescope and microscope (low power): usually

14、aperture stop is selected at the large-sized objective lens.5.2 Field of view一、Field of view2W: object field and image fieldLook out at landscape through a window. Fig 1: The field of view is limited by the size of window and by the position of the eye. Window is field stop.General speaking, field s

15、top is at image plane. ( such as telescope, microscope) The margin of reticle or film is field stop or frame.二、Field of a plane mirrorThe field of view offered by a plane mirror is very similar to that of a simple window. : observers eye, which constitutes the exit pupil. : The entrance pupil, virtu

16、al image of the eye pupil formed by mirror.Chief rays define the field of view.The object B and entrance pupil MN are in the object space. 三、How can you define the field of view of a convex mirror? 四、Field of a positive lensThe pupil of eye is an exit pupil and aperture stop.: the image of eye is an

17、 entrance pupil.The field stop in this case is the lens itself.Object is in a position inside the primary focal point . Through each of three points 、 , rays are drawn from to lens.Refracted rays are directed through 、, virtual image is located at .*When converging lens is used as a magnifier, the e

18、ye should be placed close to the lens, since this widens the image-fieldangle.For visual visional optical instruments, the eye should be placed the exit pupil of optical system, such as telescopes and microscopes.五、Entrance window and exit windowEntrance window is the image of field stoop formed by

19、all lenses preceding it.Exit window is the image of field stoop formed by all lenses following it. Both entrance and exit window are at infinity.六、Aperture angle and field angleAperture angle: Aperture angle in the object space. On-axis point subtend to the margin of entrance pupil.: Aperture angle

20、in the image space. On-axis image point subtend to the margin of exit pupil.Field angle: The center of entrance pupil subtended to the margin of entrance window.: The center of exit pupil subtended to the margin of exit window.5.3 Vignetting and Field lens一、VignettingAt small filed of view, the high

21、est and lowest rays passing through the lens, strike the top and bottom of,.At greater field of view, entrance upper and lower rays are often limited by the front and rear lens openings. The failure of an oblique beam is known as vignetting.The brightness of an image will be gradually decreased dark

22、en, when the field of view increased.Coefficient of vignetting Chief ray (principal ray): passes through the middle of aperture stop from off-axis object point or the ray that enters the lens midway between the highest and lowest rays of oblique beam. 二、Field lens(1) In order to reduce the size of f

23、ollowing optical system, field lens is usually at the image plane. (See chapter I)Free from There are only field curvature and distortion caused by . (2)Field lens can be used to change the position of exit pupil to satisfy pupil connection.Exit pupil of preceding system should be coincide with entr

24、ance pupil of following system.I Galilean telescope Aperture stop: rim of objective so is entrance pupilField stop: eye piece so is exit windowII Kepler telescopereticle is field stop. Entrance window and exit window are at infinity. Field angle:Exit pupil is close to .if eye iris is less than exit

25、pupil, iris is aperture stop. III Microscope with low magnificationAperture stop is the rim of objective so is entrance pupil.Field stop is the rim of reticle.Entrance window coincides with object plane.Exit window coincide with image plane (infinity).5.4 Telecentric systemI object space telecentric

26、 systemII image space telecentric systemIII double telecentric system*In most cases, the aperture stop is located somewhere inside the lens, such as photographic cameras.*eyepieces condenser are exceptions. 一、Telecentric system1) Telecentric system in the object space: The aperture stop is at the re

27、ar focal plane .The entering principal ray is parallel to axis. 2) Telecentric system in the image space: The aperture stop is at the front focus .The entering beam come from infinity, and exiting principal ray is parallel to axis. 3)Telecentric system at the both ends:The aperture stop is at . and

28、are coincided. The system usually used as inverting system and relay lens.二、 Contour projectorContour or profile projector is a instrument for projecting a magnified image of a small mechanical parts to check its dimensions. The optical system is invariable telecentric, the virtual of a telecentric

29、system is that the size of the projected image does not alter, if the image is slightly out of focus. The diameter of the lens aperture must be greater than the diameter of the object.Condenser lens near the lamp, providing collimated light, must also be larger than the largest object to be projecte

30、d.Final image is generally projected on a ground glass screen, sometimes equipped with Fresnel lens to brighten up the outer parts of screen. 5.5 Depth of focus and depth of field 一、conceptAssuming the lens is free from all aberrations.1) There will be a ceitain plane in the object space that is pre

31、cisely conjugate to the film plane in the image space. This is known as the focused plane in the object.2) The observers eyes have a limited acuity. There will be a small amount of tolerable blur in a photograph that observer will be unable to distinguish it from sharp image.a point object may be im

32、aged as a small circle of confusion on the film.The depth of focus of lens is the distance along the of sharp definition to the plane where the image of a point source just reaches this circle of confusion.The depth of field of lens is the corresponding distance of an object point from the focused p

33、lane in object space to the plane where its image reaches the permissible circle of confusion in the film plane.二、calculation1. Depth of focus is obviously equal to the product of the diameter of the permissible circle of confusion on the film and the F-Number F of the lens.The distance is the same

34、whether the image is just within or just beyond the film plane. how large?When a picture is viewed by an observer, most people are incapable of distinguishing between a perfect point and a small circle of confusion that subtends about 2 arc-min.2. The depth of fieldThe diagram is based on the fact t

35、hat everything lying in the focused plane will be imaged sharply on the film. is the object of (circle of confusion in image space) or the diameter of the acceptable circle of confusion in the focused plane. and are the far and near object point which is imaged and forms a circle of confusion .is fa

36、r depth of field.is near depth of field.; , is larger than.(>) If , entrance pupil equal to circle of confusion in object space. becomes infinity.(， )if 2a is reduced, the depth of field increased.Far object point Near object point The diameter of aperture stop controls five separate performance

37、of system.1) System field of view determined by vignetting.2) Photometric speed of system or light collecting ability.3) Depth of focus and depth of field. 4) Amount of aberration degrading image quality.5) Diffraction based performance of system.5.6 stray light in lenses Stray light does not form a

38、ny recognizable ghost or flare spots, it is generally referred to as veiling glare.This has the effect of lowering the overall contrast of the image.How come (arise)?1) Arise from mechanical scattering on the inside of the lens barrel and ground rims of the lenses.2) Arise from interreflection between pairs of lens surfaces.Since the surface is spherical and