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1、Ch2.幾何光學與照度學2010/03/16陳正健Outline 1.幾何光學(Geometric optics)2.照度學與光度學之定義與單位(Definition and units)3.光通量與視效函數(Lumens and eye sensitivity function)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Outline 1.幾何光學(Geometric optics)2.照度學與光度學之定義與單位(Definition and units)3.光通量與視效函數(Lumens and eye sensitivity functio
2、n)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Rectilinear propagation1.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=反射角粗糙面粗糙面鏡面鏡面F：焦點(實)F：焦點(虛)反射率：01。反射時能量的損耗。RefractionSnells law：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:全反射角：n1n2Outline 1.幾何光學(Geo
3、metric optics)2.照度學與光度學之定義與單位(Definition and units)3.光通量與視效函數(Lumens and eye sensitivity function)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Definition and unitsRadiometry 照度學Photometry 光度學W Flux 光通量lmW/Intensity 光強lm/=cdW/m2Irradiance 照度lm/m2=luxW/m2*Radiance 輝度lm/m2*Radiometry：機器實際量測得的。為絕對值。Phot
4、ometry：為人眼所感知，不同顏色有其不同的響應。1.點光源(point light source)：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(extended light source)：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()Outline 1.幾何光學(Geometric optics)2.照度學與光度學之定義與單位(Definition and units)3.光通量與視效函數(Lumens and eye sensitivity function)4.光強(Int
5、ensity)5.照度(Irradiance)6.輝度(Radiance)eye sensitivity functionV()：明視覺V()：暗視覺NormalizedLuminous efficiency1W的555 nm的綠光有 683lm。1 lm為555nm 在發出1/683 W所產生的。Pe,：為不同波光下的光功率V()：視效函數Luminous efficiency：lum/IVExample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Outline 1.幾何光學(Geometric optics)2.照度學與光度學之定義與單位(Definitio
6、n and units)3.光通量與視效函數(Lumens and eye sensitivity function)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Intensity:Point sourceIntensity立體角():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/or candela(cd)。Light patternFWHM:102配光曲線 or 散角分佈FWHM：半高全寬full width half at maximum Definition of mid-fieldMid-field
7、Far-fieldNear-fieldIn the mid-field,the light pattern varies one plane to another.If the light patterns in various planes in the mid-filed is well predicted,the optical model of the light sources is well developed.Reference:C.C.Sun,T.-X.Lee,S.-H.Ma,Y.-L.Lee,and S.Huang,“Precise optical modeling for
8、LED lighting verified by cross correlation in the midfield region,”Opt.Lett.31,2193-2195(2006).Angular fieldOutline 1.幾何光學(Geometric optics)2.照度學與光度學之定義與單位(Definition and units)3.光通量與視效函數(Lumens and eye sensitivity function)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)IrradianceIrradiance(E)：被照體單位面積
9、上所受之光通量，也就是物體表面被照明程度的量Point source:Cosine first law of irradianceUnits：lm/m2 or lux(lx)。Point source:Cosine third lawOutline 1.幾何光學(Geometric optics)2.照度學與光度學之定義與單位(Definition and units)3.光通量與視效函數(Lumens and eye sensitivity function)4.光強(Intensity)5.照度(Irradiance)6.輝度(Radiance)Lambertian surfaceRadi
10、anceThe radiance of a surface element is independent of the direction of radiation if its intensity is proportional to cos .Such a surface is said to obey Lamberts cosine law of intensityA surface that radiates uniformly in all directions is called a Lambertian surface or a uniform diffuser.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/m2 or nit。Thanks for your attentions!