PrinciplesofLight光学基本原理

PrinciplesofLight光学基本原理6.1NaturalofLight光的性质

whatislight?Lightisenergyintheformofelectromagneticradiation

光是以电磁波形式传播的(辐射)

electromagneticspectrum电磁辐射波谱UV：紫外线istheshortof(ultraviolet)IR:istheshortof（infra-red)PrinciplesofLight光学基本原理Lighttravelinstraightlinesbutcanbeaffectedbythefollowingeffects.Reflection反射howdolighttravel?Refraction:折射Diffraction:衍射PrinciplesofLight光学基本原理LighttravelinstraightlinesPrinciplesofLight光学基本原理Reflection反射PrinciplesofLight光学基本原理Refraction:折射PrinciplesofLight光学基本原理Diffraction:衍射PrinciplesofLight光学基本原理whatisVisibleradiation可见光Thewavelengthsofelectromagneticradiationthatarevisibletotheeyerangefromapproximately380nmto760nm.nm_nanometre纳米10-9m380nm760nmPrinciplesofLight光学基本原理Whatiswhitelight?什么是白光？Ifallthewavelengthsoflightareseenatthesametimetheeyecannotdistinguishtheindividualwavelengthsandthebrainhasthesensationofwhitelight.380nm760nmPrinciplesofLight光学基本原理Whitelightcanbeseparatedintoitscomponentwavelengthsusingaglassprism棱镜,

Monochromaticlight单色光

islightofoneparticularwavelengthandcolorPrinciplesofLight光学基本原理whatisNon-visibleradiation不可见光Electromagneticradiationswithwavelengthsoutsidetherangeofvisiblewavelengthscannotbedetectedbythehumaneye.Ultra-violetInfra-redPrinciplesofLight光学基本原理Infra-redradiation红外线

Infra-redradiationhaswavelengthsslightlygreaterthanthoseofredlightandcanbefeltasheatradiationfromtheSunandfromotherheatedbodies.Infra-redradiationismadeuseofinradiantheatingdevices,fordetectingpatternsofheatemission,for“seeing”inthedark,andforcommunicationlinks.PrinciplesofLight光学基本原理Ultra-violet紫外线Ultra-violetradiationhaswavelengthsslightlylessthanthoseofvioletlight.ItisemittedbytheSunandalsobyotherobjectsathightemperature.Ultra-violetradiationhelpskeepthebodyhealthybutexcessiveamountscandamagetheskinandtheeyes.Ultra-violetradiationcanbeusedtokillharmfulbacteriainkitchensandinhospitals.CertainchemicalscanconvertUVenergytovisiblelightandtheeffectismadeuseofinfluorescentlamps荧光灯.PrinciplesofLight光学基本原理thestructureoftheeyeConevision锥体细胞

isadaptedtonormallevelsoflightandisusedtoforseeingdetailsanddistinguishcolourRodvision杆状细胞

isadaptedtoverylowlevelsoflightandisverysensitivetolightbutcannotdistinguishcolourretina视网膜6.2Natureofvision视觉特征

PrinciplesofLight光学基本原理terminologyofvision视觉术语Visualfield视野

IsthetotalextentinspacethatcanbeseenwhenlookinginagivendirectionVisualacuity视觉敏锐度

Istheabilitytodistinguishbetweendetailsthatareveryclosetogether.Adoption视觉适应

Istheprocessoccurringastheeyesadjuststotherelativebrightnessorcolourofobjectsinthevisualfield.Contrast视觉对比度

isthedifferentinbrightnessorcoloursbetweentwopartsofthevisualfield.180

PrinciplesofLight光学基本原理6.3howtomeasurelighting光的度量Lightisoneformofenergyandcouldbemeasuredbythestandardunitsofenergy.Buttheeffectoflightonthehumanenvironmentalsodependsuponthesensitivityoftheeyeandaspecialsetofunitshasbeendevelopedforthemeasurementoflightanditseffects.Luminousflux光通量Solidangle立体角Luminousintensity发光强度Illuminance照度Luminance亮度PrinciplesofLight光学基本原理whichonecangivemorelight?

Luminousflux光通量

istherateofflowoflightenergy

辐射体单位时间内以电磁辐射的形式向外辐射的能量称为辐射功率或辐射通量其中被人眼感觉为光的那部分成为光通量。

Unit:lumen(lm)1lm=1/683WfluorescentlampsIncandescentlampsPrinciplesofLight光学基本原理whatisSolidangle立体角lightcanradiateinallthreedimensionsthespacearoundapointcanbedividedinto“solidangles”ThestandardSIunitofsolidangleisthesteradian球面度(立体角单位PrinciplesofLight光学基本原理Acompletespherecontainsatotalof4steradiansPrinciplesofLight光学基本原理whichonewouldyouchoose?Luminousintensity发光强度Unit:candela(cd)ThecandelaisoneofthebaseunitsintheSIsystem.PrinciplesofLight光学基本原理Illuminance照度Whenluminousfluxfallsonasurfaceitilluminatethatsurface.IlluminanceisthedensityofluminousfluxreachingasurfaceUnit:lux(lx)1lx=1lumen/(meter)2Iflightisfallingasurfaceatrightanglestothesurfacethentheilluminanceisgivenbythefollowingformula.PrinciplesofLight光学基本原理22

Illuminance照度inseveraldifferentcasesPrinciplesofLight光学基本原理Figure5.3SummaryoflightingmeasurementsMcMullanPrinciplesofLight光学基本原理Inversesquarelawofillumination

照度的平方反比定律Thellluminanceproducedbyapointsourceoflightdecreasesininverseproportiontothesquareofthedistancefromthesource.MaybeexpressedbythefollowingformulaPrinciplesofLight光学基本原理

Alamphasaluminousintensityof1200cdandactsasapointsource.Calculatetheilluminanceproducedonsurfacesatthefollowingpositionsa)At2mdistancefromthelamp,andb)At6mdistancefromthelampKnow:I=1200cdd1=2mandd2=6m,E=?UsingE1=1200/22=300lxE2PrinciplesofLight光学基本原理

Cosinelawofillumination照度的余弦定律lightstrikesmanysurfacesataninclinedangleandthereforeilluminateslargerareasthanwhenitstrikesatarightangle.CanbecalculatedusingAnglebetweendirectionoffluxandthenormalPrinciplesofLight光学基本原理

Alampactsasapointsourcewithameansphericalintensityof1500cd.Itisfixed2mabovethecentreofacirculartablewhichhasaradiusof1.5m.Calculatetheilluminanceprovidedattheedgeofthetable,ignoringreflectedlight.know:I=1500cd,E=?Using:trianglelaws三角形定律Note:youdonotneedtoknowtheactualvalueoftheangleindegreesUsing2mPrinciplesofLight光学基本原理Diffusereflection漫反射Specularflection镜面反射Reflection反射Reflectance反射率istherationoftheluminousfluxreflectedfromasurfacetothefluxincidentuponthesurfacePrinciplesofLight光学基本原理

Apointsourceoflightwithaluminousintensityof1800cdisset3mabovethefloorand1mbelowtheceilingwhichhasareflectanceof0.5.calculatethedirectandreflectedcomponentoftheilluminanceonthefloorbeneaththelightKnowI=1800cdd=3mE=?UsingSodirectcomponent=200lxd=1+1+3=5m1m3mPrinciplesofLight光学基本原理whichoneisbrighter?Self-luminoussources自发光光源Theluminanceisgivenbythefollowingformulaunit:cd/m2aspotlamp聚光灯afluorescenttubehavethesameluminousintensity;PrinciplesofLight光学基本原理31

亮度和照度有何区别？照了不一定亮！吸光材料，亮度低反光材料，亮度高Reflectingsurface反射表面unit:apostilb阿波熙提(应用于扩散表面的亮度单位)where1asb=1lumen/m2PrinciplesofLight光学基本原理

thecandelapersquaremetreisthecorrectSIunitofluminance.Theapostilbisanalternativeunitofluminancewhichisconvenientforsomecalculations1apostilb=1/cd/m2cd/m21asb=1lumen/m2Self-luminoussources自发光光源Reflectingsurface反射表面PrinciplesofLight光学基本原理Solidangle立体角Luminousintensity发光强度Luminousflux光通量Illuminance照度Luminance亮度Steradian球面度candela(cd)lumen(lm)lux(lx)cd/m21lm=1/683W1lm/m21apostilb=1/cd/m2Drawoutalisttocomparetheseparameters

PrinciplesofLight光学基本原理Self-luminoussources自发光光源Theluminanceisgivenbyunit:cd/m2Reflectingsurface反射表面1apostilb=1/cd/m21asb=1lumen/m2PrinciplesofLight光学基本原理AgoodlightenvironmentrequiresasuitablelightdistributionPrinciplesofLight光学基本原理PrinciplesofLight光学基本原理whatisGlare眩光Glareisthediscomfortorimpairment

损害ofvisioncausedbyanexcessiverangeofbrightnessinthevisualfield.Glarecanbecausedbywhat?lamps,

windowsandpaintedsurfacesappearingtoobrightincomparisonwiththegeneralbackground.GlareCanbefurtherdescribedasDisabilityglare失能眩光Discomfortglare不舒适眩光PrinciplesofLight光学基本原理howtomeasureLight?APhotometer

光度计isaninstrumentthatmeasurestheluminousintensityofalightsourcebycomparingitwithastandardsourcewhoseintensityisknown.Aphotocelllightmeter

光电仪isaninstrumentthatdirectlymeasurestheilluminanceonasurface.Theelectricalresistanceofsomesemiconductors,suchasselenium硒,changeswithexposuretolightandthispropertyisusedinanelectricalcircuitconnectedtoagalvanometer检流计.Thismetermaybecalibratedinlux.PrinciplesofLight光学基本原理

DoeslighthasDirectionalquality?

光有方向吗？

Wecandescribeitsdirectionalpropertyusingthefollowingparameters

Illuminationvector照明矢量Scalarilluminance照明标量Vector/scalarratio矢量/标量比Becauseofthelimitedtime,wewon’ttalktoomuchabouttheseparametersPrinciplesofLight光学基本原理6.4Color色彩

pleasereadthispartbyyourselfafterclassColoursystemsCIEcolorcoordinatesMunsellsystemColourreproductionAdditivecolourAdditiveprimarycoloursApplicationofadditivecolourStagelightingColourtelevisionColourprinting

PrinciplesofLight光学基本原理

6PrinciplesofLight5.1whatislight?

5.1.1howislighttravel?5.1.2whatisVisibleradiation可见光5.1.3whatisNon-visibleradiation不可见光5.2Natureofvision视