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1、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 abilityFor a visual optical system: the human eye is the receiver of the system.human eyesThe visual optical systemre
2、quire ?3.1 Characteristics of the Eye 3.1.1、structure of the eye:Eyes cameraPupil(瞳孔) stop(光阑)Retina Choroid Sclera Iris Frontal chamber Cornea Axis Yellow spotBlind spotLens of eyecamera lensRetina(视网膜) film(底片)lens 3.1.2 the Accommodation of the EyeEye , two kinds of accommodation functions:diopte
3、r accommodation and pupil accommodation(1) Diopter accommodation For a normal relaxed eye: the infinite object images on the retina (视网膜).The second focal point of the eye: retinaThe eye muscles are most relaxed when the eye is looking at distant objects (“at infinity”).the unit : Diopter/屈光度,视度from
4、 the eye to the object plane.unit:m/meter Ex.:object,then,When at infinity,Measuring for the accommodation degree of the eye:accommodationThe normal reading distance/明视距离明视距离: : 250mm (Distance of most distinct vision)Near point/近点: a closest point at which the eye can see an object.The least distin
5、ct distance or near point distance/近点距离Far point/远点远点: :The far point distance/远点距离: the longest distance which the eye can see clearly.SD Near point SD Far pointFor a normal eye:The maximum accommodation range of the eye:SD Near point SD infinityFar point/Far point/远点远点: : at infinityThe maximum ac
6、commodation range of the eye is restricted by ages.AgesMaximum accommodation range/DiopterNear point distance/mm10-147015-128320-1010025-7.813030-7.014035-5.518040-4.522045-3.529050-2.5400(2) Pupil accommodation2mm 8mm3.1.3 visual AcuityFor two points, For lines, 3.2 principles of Magnifier and Micr
7、oscopeMagnifying 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 Magnifierthe normal reading distance/the normal reading distance/明视距离明视距离2. The virtual image of
8、 Magnifier is at 250mm,Discussion :3. A magnifier usually consists of a single lens, 1. Ifthen 2.then,3.2.2 The Microscope3.2.2 The MicroscopeobjectiveeyepieceStructure:objective(物镜)+ eyepiece(目镜)思考:比较显 微镜和放大镜 的异同?A microscope a complex magnifierP186The resolution of a microscope:the smallest separa
9、tion between two object points: NA= nsinU numerical aperture of the systemNote that the index n and 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 isSolution:Using,If we
10、 use a eyepiece, then the objective:3.3 principle of TelescopeStructure: objective + eyepieceTelescopes Afocal Systems(无焦系统)Three types of telescopes: Kepler Telescope, Galilean Telescope, The erecting(正立) Telescope1. Types of telescopesa) Kepler Telescope: Positive objective + Positive eyepiece inv
11、erted real image,Application: Astronomical telescopesWe can add a reticule on the internal image plane for aiming and measuring.b) Galilean Telescope: Positive objective + negative eyepieceerect virtual image,Application: watching operasc) The erecting(正立) Telescope: Erector: lens, or prismerect rea
12、l image,Application: military telescopesobjectiveerectoreyepiecePrism Erecting TelescopeDiscussion:The angular magnification, lateral magnification, 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 5k
13、ilometers, =? solution:By the naked eye,a telescope:solution:then:the angular error in the image space:the aiming angular error :Example 2. If a theodolite telescope, If using the method of alignment of two strait lines, what is the aiming angular error?2.2.the angular resolution of a telescopethe a
14、ngular resolution of a telescope (in object space): (in object space): In air,P184-185Dthe diameter of a telescope, unit: mmD ,3.4 Defect of Eyes and Diopter Accommodation of Optical Instruments 1. Myopia and HyperopiaFor a normal eye:The far point is The far point is at infinityA nearsighted eye/my
15、opia(近视眼):F falls ahead of the retina.farsightedness/hyperopia(远视):F falls behind of the retina.myopiahyperopiaFor example, a nearsighted eye, The myopic degree is often expressed by the diopter of its far point distance.the normal reading distance and the near point distanceA nearsighted eye/myopia
16、(近视眼):(SD=-2+(-4)=-6)the normal reading distance:-16.7mmthe the near point distance with -10D accommodation:Example, with +2 diopters of hyperopiaand -10D of accommodation range. Then ,Farsightedness/Hyperopia(远视):A hyperopic person can possibly see the infinite object. But the near point distance will be increased.myopia(近视): a ne