镜头光学设计

1鏡頭光學規格的介紹Curtis主題2Curtis內容大綱1PixelSize2ImageSize3ImageCircle4LensComposition5FieldOfView(FOV)6FNumber7Relativeillumination(RI)8ChiefRayAngle(CRA)9Distortion10MTF11EFL12BackFocusLength(BFL)13OpticalTotalLength3LCM-****2Mega(Design)ItemLCM-****SensorMI-XXXX，OV-XXXXPixelSize3.2x3.2μmImageSizeD:5.6mm(H:4.48V:3.36)ImageCircleφ5.9mmLensComposition1G3PFieldOfView59.5゜(atSENSORDiagonal)FNumberF/2.8Relativeilluminationat100%ofImageHeight55%(atSENSORDiagonal)ChiefRayAngleD:19.7゜H:20.6゜V:20.5゜TVDistortion1%MTFCenterCenter54%@180LP/mm50%@200LP/mmat70%ofImageHeighth=70%T61%/S74%@90LP/mmat80%ofImageHeighth=80%T59%/S69%@90LP/mmat90%ofImageHeighth=90%T58%/S63%@90LP/mmat100%ofImageHeighth=100%T59%/S72%@90LP/mmFocusLengthf=4.87mmBackFocusLength1.494mmOpticalTotalLength6mmIRCF650±15nm@50％SPEC.Curtis未來發展4CurtisBFL基本光學系51、Imagecirclesensorsize(D)。2、D+0.4mm(Package公差)。MEMO：光學設計的考量，要從了解SENSOR開始。光學設計需與SENSOR達到最佳配合。PLWDP=Pixelsizesensor1Curtis6RatioTypeNameAspectRatio(W:H)Diameter(mm)Width(mm)Height(mm)Diagonal(mm)Diameter/Diagonal1/3.64:37.064.003.005.001.411/3.24:37.944.543.425.681.401/34:38.474.803.606.001.411/2.74:39.415.374.046.721.401./2.54:310.165.764.297.181.411/24:312.706.404.808.001.591/1.84:314.117.205.359.001.572/34:316.938.806.6011.001.5414:325.412.809.6016.001.594/34:333.8717.4013.1021.781.561.83:245.7223.7015.7028.401.6135mmfilm3:2n/a36.0024.0043.27n/aTypeSensorsensor2Curtis尺寸表7FOV:FieldOfViewDθθfFOV=2θ=2tan-1[D/2f]FOVsensor例：SENSOR對角線D=5mm，焦點距離f=3mm，則FOV為：FOV=2θ=2tan-1[5/2*3]=79.6(度)Curtis8F/#_1DfsensorF/#：決定光通量、影像的亮度。F/#=f/DI0∝1/(F/#)2………(進光量與F/#平方成反比)。I0≡ImageIntensity流明≡照度MEMO：F/#數值愈小→設計上困難度愈高。FOV愈大→設計上困難度愈高。Curtis9F/#_2．F/2.8比F/4.0亮度亮兩倍。例：F/#=2.8&4，焦點距離f=50mm，則入光大小為：F/#=f/D；D=f/F/#1、D(F/2.8)=50/2.8=17.862、D(F/4.0)=50/4.0=12.51、D(F/2.8)=50/2.8=17.862、D(F/4.0)=50/4.0=12.5．以圓面積計算公式計算如下：(πR2)1、3.14*17.862≒10022、3.14*12.52≒491(面積F/2.8)≒2*(面積F/4.0)Curtis10F/#_3．CCD靈敏度較CMOS為高。不致能區線性區飽和區exposureresponseMEMO：CCD所使用的F/#值較大(即光圈較小)。如果使用過大的光圈，則會落於飽和區使得成像品質不好。Curtis11MTF1黑白Co≡(Bmax–Bmin)/(Bmax+Bmin)=contrast代表的是層次感、立體感。Lensdesign→GoodimageQualityImageQuality：．MTF．Distortion．CRA(tele-centricangle)．RI．Flare&GhostBmaxBminCurtis12050100MTF0.51.0(lp/mm)MTF2截止頻率→→MTF≡Ci/CoCo：物Ci：像OpticalsystemNon-perfectlens因材料、加工、組立所產生的缺陷。100%70%Curtis13MTF3S：Sagittal，弧矢面，放射狀。T：Tangential，子午面，同心圓狀。Curtis14MTF401001.0(lp/mm)截止頻率fN．Aliasing現象FalsecolorMoire’patternfN=Nyquistfrequency=1/2p例：p=3.2μmfN=1/(2*3.2*0.001)=1000/6.4=156(lp/mm)MEMO：如何消除Aliasing?→利用“OLPF”。Curtis15OLPF101.0(lp/mm)fN01.0鏡頭MTFOLPF_MTF1.0(lp/mm)01.0(lp/mm)fNfNOLPF：1、雙折射式(Crystal、quartz)2、繞射式(grating光柵)Curtis16OLPF2falsecolorsCurtis17IR_CUTFilter_114:33:24IR_CUTFilterIR_CUTFilter1、反射式(Reflectiontype)：干涉鍍膜。2、吸收式(Absorptiontype)：藍玻璃。Curtis18IR_CUTFilter_2規格標示例：650nm±15nm@T=50％Curtis19IR_CUTFilter_3．反射式IR_CUTFilter的Angleshift問題→入射角度增加，截止波長往短波長偏移。．吸收式_(藍玻璃、綠玻璃)→無Angleshift問題→但，材料特性為質軟、容易起化學變化，容易吸水有潮解現象，耐候性不佳等問題。Curtis20CRA_1C.R.(30°)CRA(α)◎ChiefRayAngle(CRA)A.SI0IθImageplaneθ與CRA有關的參數：1、cos4θLaw：Iθ=I0cos4α2、RI=Iθ/I0(相對照度)Curtis21CRA_225°．Sensor端會要求CRA符合此角度→配合microlens的調整。(microlens與sensor的距離，影響CRA需求的大小)例：SENSOR的CRA要求希望α25°，A、RI=50％at30°(θ)B、RI=55％at30°(θ)誰優?實裝上，A周邊光亮比B亮，為何?→因為，A的CRA(α)=25°；B的CRA(α)=30°A比B能配合SENSOR，故A比B亮。Curtis