PrinciplesofLight光學(xué)基本原理

PrinciplesofLight光學(xué)基本原理6.1NaturalofLight光的性質(zhì)

whatislight?Lightisenergyintheformofelectromagneticradiation

光是以電磁波形式傳播的(輻射)

electromagneticspectrum電磁輻射波譜UV：紫外線istheshortof(ultraviolet)IR:istheshortof（infra-red)PrinciplesofLight光學(xué)基本原理Lighttravelinstraightlinesbutcanbeaffectedbythefollowingeffects.Reflection反射howdolighttravel?Refraction:折射Diffraction:衍射PrinciplesofLight光學(xué)基本原理LighttravelinstraightlinesPrinciplesofLight光學(xué)基本原理Reflection反射PrinciplesofLight光學(xué)基本原理Refraction:折射PrinciplesofLight光學(xué)基本原理Diffraction:衍射PrinciplesofLight光學(xué)基本原理whatisVisibleradiation可見光Thewavelengthsofelectromagneticradiationthatarevisibletotheeyerangefromapproximately380nmto760nm.nm_nanometre納米10-9m380nm760nmPrinciplesofLight光學(xué)基本原理Whatiswhitelight?什么是白光？Ifallthewavelengthsoflightareseenatthesametimetheeyecannotdistinguishtheindividualwavelengthsandthebrainhasthesensationofwhitelight.380nm760nmPrinciplesofLight光學(xué)基本原理Whitelightcanbeseparatedintoitscomponentwavelengthsusingaglassprism棱鏡,

Monochromaticlight單色光

islightofoneparticularwavelengthandcolorPrinciplesofLight光學(xué)基本原理whatisNon-visibleradiation不可見光Electromagneticradiationswithwavelengthsoutsidetherangeofvisiblewavelengthscannotbedetectedbythehumaneye.Ultra-violetInfra-redPrinciplesofLight光學(xué)基本原理Infra-redradiation紅外線

Infra-redradiationhaswavelengthsslightlygreaterthanthoseofredlightandcanbefeltasheatradiationfromtheSunandfromotherheatedbodies.Infra-redradiationismadeuseofinradiantheatingdevices,fordetectingpatternsofheatemission,for“seeing”inthedark,andforcommunicationlinks.PrinciplesofLight光學(xué)基本原理Ultra-violet紫外線Ultra-violetradiationhaswavelengthsslightlylessthanthoseofvioletlight.ItisemittedbytheSunandalsobyotherobjectsathightemperature.Ultra-violetradiationhelpskeepthebodyhealthybutexcessiveamountscandamagetheskinandtheeyes.Ultra-violetradiationcanbeusedtokillharmfulbacteriainkitchensandinhospitals.CertainchemicalscanconvertUVenergytovisiblelightandtheeffectismadeuseofinfluorescentlamps熒光燈.PrinciplesofLight光學(xué)基本原理thestructureoftheeyeConevision錐體細(xì)胞

isadaptedtonormallevelsoflightandisusedtoforseeingdetailsanddistinguishcolourRodvision桿狀細(xì)胞

isadaptedtoverylowlevelsoflightandisverysensitivetolightbutcannotdistinguishcolourretina視網(wǎng)膜6.2Natureofvision視覺特征

PrinciplesofLight光學(xué)基本原理terminologyofvision視覺術(shù)語Visualfield視野

IsthetotalextentinspacethatcanbeseenwhenlookinginagivendirectionVisualacuity視覺敏銳度

Istheabilitytodistinguishbetweendetailsthatareveryclosetogether.Adoption視覺適應(yīng)

Istheprocessoccurringastheeyesadjuststotherelativebrightnessorcolourofobjectsinthevisualfield.Contrast視覺對比度

isthedifferentinbrightnessorcoloursbetweentwopartsofthevisualfield.180

PrinciplesofLight光學(xué)基本原理6.3howtomeasurelighting光的度量Lightisoneformofenergyandcouldbemeasuredbythestandardunitsofenergy.Buttheeffectoflightonthehumanenvironmentalsodependsuponthesensitivityoftheeyeandaspecialsetofunitshasbeendevelopedforthemeasurementoflightanditseffects.Luminousflux光通量Solidangle立體角Luminousintensity發(fā)光強度Illuminance照度Luminance亮度PrinciplesofLight光學(xué)基本原理whichonecangivemorelight?

Luminousflux光通量

istherateofflowoflightenergy

輻射體單位時間內(nèi)以電磁輻射的形式向外輻射的能量稱為輻射功率或輻射通量其中被人眼感覺為光的那部分成為光通量。

Unit:lumen(lm)1lm=1/683WfluorescentlampsIncandescentlampsPrinciplesofLight光學(xué)基本原理whatisSolidangle立體角lightcanradiateinallthreedimensionsthespacearoundapointcanbedividedinto“solidangles”ThestandardSIunitofsolidangleisthesteradian球面度(立體角單位PrinciplesofLight光學(xué)基本原理Acompletespherecontainsatotalof4steradiansPrinciplesofLight光學(xué)基本原理whichonewouldyouchoose?Luminousintensity發(fā)光強度Unit:candela(cd)ThecandelaisoneofthebaseunitsintheSIsystem.PrinciplesofLight光學(xué)基本原理Illuminance照度Whenluminousfluxfallsonasurfaceitilluminatethatsurface.IlluminanceisthedensityofluminousfluxreachingasurfaceUnit:lux(lx)1lx=1lumen/(meter)2Iflightisfallingasurfaceatrightanglestothesurfacethentheilluminanceisgivenbythefollowingformula.PrinciplesofLight光學(xué)基本原理22

Illuminance照度inseveraldifferentcasesPrinciplesofLight光學(xué)基本原理Figure5.3SummaryoflightingmeasurementsMcMullanPrinciplesofLight光學(xué)基本原理Inversesquarelawofillumination

照度的平方反比定律Thellluminanceproducedbyapointsourceoflightdecreasesininverseproportiontothesquareofthedistancefromthesource.MaybeexpressedbythefollowingformulaPrinciplesofLight光學(xué)基本原理

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

Cosinelawofillumination照度的余弦定律lightstrikesmanysurfacesataninclinedangleandthereforeilluminateslargerareasthanwhenitstrikesatarightangle.CanbecalculatedusingAnglebetweendirectionoffluxandthenormalPrinciplesofLight光學(xué)基本原理

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

Apointsourceoflightwithaluminousintensityof1800cdisset3mabovethefloorand1mbelowtheceilingwhichhasareflectanceof0.5.calculatethedirectandreflectedcomponentoftheilluminanceonthefloorbeneaththelightKnowI=1800cdd=3mE=?UsingSodirectcomponent=200lxd=1+1+3=5m1m3mPrinciplesofLight光學(xué)基本原理whichoneisbrighter?Self-luminoussources自發(fā)光光源Theluminanceisgivenbythefollowingformulaunit:cd/m2aspotlamp聚光燈afluorescenttubehavethesameluminousintensity;PrinciplesofLight光學(xué)基本原理31

亮度和照度有何區(qū)別？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(應(yīng)用于擴散表面的亮度單位)where1asb=1lumen/m2PrinciplesofLight光學(xué)基本原理

thecandelapersquaremetreisthecorrectSIunitofluminance.Theapostilbisanalternativeunitofluminancewhichisconvenientforsomecalculations1apostilb=1/cd/m2cd/m21asb=1lumen/m2Self-luminoussources自發(fā)光光源Reflectingsurface反射表面PrinciplesofLight光學(xué)基本原理Solidangle立體角Luminousintensity發(fā)光強度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光學(xué)基本原理Self-luminoussources自發(fā)光光源Theluminanceisgivenbyunit:cd/m2Reflectingsurface反射表面1apostilb=1/cd/m21asb=1lumen/m2PrinciplesofLight光學(xué)基本原理AgoodlightenvironmentrequiresasuitablelightdistributionPrinciplesofLight光學(xué)基本原理PrinciplesofLight光學(xué)基本原理whatisGlare眩光Glareisthediscomfortorimpairment

損害ofvisioncausedbyanexcessiverangeofbrightnessinthevisualfield.Glarecanbecausedbywhat?lamps,

windowsandpaintedsurfacesappearingtoobrightincomparisonwiththegeneralbackground.GlareCanbefurtherdescribedasDisabilityglare失能眩光Discomfortglare不舒適眩光PrinciplesofLight光學(xué)基本原理howtomeasureLight?APhotometer

光度計isaninstrumentthatmeasurestheluminousintensityofalightsourcebycomparingitwithastandardsourcewhoseintensityisknown.Aphotocelllightmeter

光電儀isaninstrumentthatdirectlymeasurestheilluminanceonasurface.Theelectricalresistanceofsomesemiconductors,suchasselenium硒,changeswithexposuretolightandthispropertyisusedinanelectricalcircuitconnectedtoagalvanometer檢流計.Thismetermaybecalibratedinlux.PrinciplesofLight光學(xué)基本原理

DoeslighthasDirectionalquality?

光有方向嗎？

Wecandescribeitsdirectionalpropertyusingthefollowingparameters

Illuminationvector照明矢量Scalarilluminance照明標(biāo)量Vector/scalarratio矢量/標(biāo)量比Becauseofthelimitedtime,wewon’ttalktoomuchabouttheseparametersPrinciplesofLight光學(xué)基本原理6.4Color色彩

pleasereadthispartbyyourselfafterclassColoursystemsCIEcolorcoordinatesMunsellsystemColourreproductionAdditivecolourAdditiveprimarycoloursApplicationofadditivecolourStagelightingColourtelevisionColourprinting

PrinciplesofLight光學(xué)基本原理

6PrinciplesofLight5.1whatislight?

5.1.1howislighttravel?5.1.2whatisVisibleradiation可見光5.1.3whatisNon-visibleradiation不可見光5.2Natureofvision視