ch2 几光与照度学VIP免费

Ch2.幾何光學與照度學2010/03/16陳正健Outline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Outline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Rectilinearpropagation1.光在各向同性的均勻介質中沿直線傳播2.不同光源以不同的方向所發出的光相遇時，不會影響相互的傳播。直線傳播定律：P1---A---P2Reflection漫反射鏡反射凹面鏡凸面鏡a=b入射角=反射角粗糙面鏡面F：焦點(實)F：焦點(虛)反射率：0~1。反射時能量的損耗。Refraction1122sinsinnnSnell’slaw：n=c/v,c:光速v:介質中的速度n=1n=1.5重介質:n較大的輕介質:n較小的折射率:12arcsin()cnn全反射角：n1>n2Outline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)DefinitionandunitsRadiometry照度學Photometry光度學WFlux光通量lmW/ΩIntensity光強lm/Ω=cdW/m2Irradiance照度lm/m2=luxW/m2*ΩRadiance輝度lm/m2*ΩRadiometry：機器實際量測得的。為絕對值。Photometry：為人眼所感知，不同顏色有其不同的響應。1.點光源(pointlightsource)：所謂的點光源是指光源為一有無限小之體積，對其四面八方各個方向輻射一樣的能量。而在自然界並無這樣的發光源。2.面光源(extendedlightsource)：所謂的面光源是指此光源是一帶有面積之光源，自然界之光源幾乎都為面光源。W=J/s()Outline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)eyesensitivityfunctionV(λ)：明視覺V’(λ)：暗視覺NormalizedLuminousefficiency,683()lumelmPVdW1W的555nm的綠光有683lm。1lm為555nm在發出1/683W所產生的。Pe,λ：為不同波光下的光功率V(λ)：視效函數Luminousefficiency：Φlum/IVExample30040050060070080090010000.00.51.01.52.0Normalizedintensity(a.u.)Wavelength(nm)常見之白光LED頻譜：各波長所帶之能量總合人眼視效函數此白光頻譜之所有流明數Outline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Intensity:PointsourceIntensity立體角(Ω):Intensity(I):光源在某一方向之立體角內所放出的光通量大小Units：lm/Ωorcandela(cd)。Lightpattern-100-80-60-40-200204060801000.00.20.40.60.81.0Normalizedintensity(a.u.)Rotatedangle(degree)FWHM:102∘配光曲線or散角分佈FWHM：半高全寬fullwidthhalfatmaximumDefinitionofmid-fieldMid-fieldFar-fieldNear-fieldInthemid-field,thelightpatternvariesoneplanetoanother.Ifthelightpatternsinvariousplanesinthemid-filediswellpredicted,theopticalmodelofthelightsourcesiswelldeveloped.Reference::C.C.Sun,T.-X.Lee,S.-H.Ma,Y.-L.Lee,andS.Huang,“PreciseopticalmodelingforLEDlightingverifiedbycrosscorrelationinthemidfieldregion,”Opt.Lett.31,2193-2195(2006).AngularfieldOutline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)IrradianceIrradiance(E)：被照體單位面積上所受之光通量，也就是物體表面被照明程度的量Pointsource:CosinefirstlawofirradianceUnits：lm/m2orlux(lx)。Pointsource:CosinethirdlawOutline1.幾何光學(Geometricoptics)2.照度學與光度學之定義與單位(Definitionandunits)3.光通量與視效函數(Lumensandeyesensitivityfunction)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)LambertiansurfaceRadianceTheradianceofasurfaceelementisindependentofthedirectionofradiationifitsintensityisproportionaltocos.SuchasurfaceissaidtoobeyLambert’scosinelawofintensityAsurfacethatradiatesuniformlyinalldirectionsiscalledaLambertiansurfaceorauniformdiffuser.Radiance(B):一光源或一被照面之輝度指其單位表面在某一方向上的光強度密度.Units：cd/m2ornit。Thanksforyourattentions!