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时间:2018-10-23
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1、Ch.15SpecialSenses:VisionSlidesmostly©Marieb&Hoehn9thed.OtherslidesbyWCR©2013PearsonEducation,Inc.LightAndOptics:WavelengthAndColorLightPacketsofelectromagneticradiation(energy)LightwaveshavedifferentwavelengthsVisiblelightThe(small)rangeofelectromagneticwavelengthswhichoureyescandetect:400-700n
2、mDifferentobjectsreflectdifferentwavelengths,whichweperceiveasdifferentcolors©2013PearsonEducation,Inc.Figure15.10Theelectromagneticspectrumandphotoreceptorsensitivities.10–5nmGammaraysXraysUVInfraredMicro-wavesRadiowavesVisiblelightBluecones(420nm)Rods(500nm)Greencones(530nm)Redcones(560nm)Ligh
3、tabsorption(percentofmaximum)10050040010–3nm1nm103nm106nm1m103m(109nm=)Wavelength(nm)450500550600650700©2013PearsonEducation,Inc.LightAndOptics:RefractionAndLensesRefractionBendingoflightraysDuetochangeinspeedwhenlightpassesfromonetransparentmediumtoanotherOccurswhenlightmeetssurfaceofdifferentm
4、ediumatanobliqueangleConvexly-curvedlensrefractlighttobringittoafocusImageformedatfocalpointisupside-downandleft-rightreversed©2013PearsonEducation,Inc.Figure15.11Refraction.©2013PearsonEducation,Inc.Figure15.12Lightisfocusedbyaconvexlens.PointsourcesFocalpointsFocusingoftwopointsoflight.Theimag
5、eisinverted—upsidedownandreversed.©2013PearsonEducation,Inc.FocusingLightonTheRetinaPathwayoflightenteringeye:cornea,aqueoushumor,lens,vitreoushumor,entireneurallayerofretina,photoreceptorsLightrefractedatboundariesalongpathwayAirtocornea/aqueoushumorAqueoushumortolensLenstovitreoushumorMostbend
6、inghappensatair-corneaboundaryLenscurvatureisthe“fineadjustment”©2013PearsonEducation,Inc.FocusingForDistantVisionEyesbestadaptedfordistantvisionFarpointofvisionDistancebeyondwhichnochangeinlensshapeneededforfocusing20feetforemmetropic(normal)eyeCorneaandlensfocuslightpreciselyonretinaCiliarymus
7、clesrelaxedLensstretchedflatbytensioninciliaryzonule©2013PearsonEducation,Inc.Figure15.13aFocusingfordistantandclosevision.SympatheticactivationNearlyparallelraysfromdistantobjectLensCiliaryzonuleCiliarymuscleInvertedimageLe
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