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 systemrequire ?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：diopter 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 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 distinct 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 accommodation 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 MicroscopeMagnifying 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 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 separation 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 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 inverted 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 real 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 5kilometers, =？ 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 angular 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/myopia(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(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