Telecentric鏡頭,又稱為遠心鏡頭) @ 阿豆腐新聞 - 隨意窩

Telecentric鏡頭,又稱為遠心鏡頭,其內部為遠心光學設計,亦即開口光圈在鏡頭的焦點位置上,可分為物體側,像側,或是兩側的遠心設計,主光線和光軸都是平行. 阿豆腐新聞黎智英辦報有名言：「只要傳真，不要高深。

」因為「故弄玄虛才是高深，那是假的」(AdolfNews)日誌相簿影音好友名片 webset41's新文章標題[爆卦]不要在哭賣淫跟財團鳥政府了南韓政治社會轉型，為什麼能成功避免革命作者：李鐵T-34一名大陸政治老師退休前的最後一課驚呆學生是趙藤雄們殺了孫中山？！（原刊於UDN王大師專欄）不改變觀念，這將永遠是死亡行業──AV女優公開信悼自殺同行『歧視學』導論李茂生：製造出隨機殺人魔王的是社會結構捷運殺人案，產生4個死者，大家驚恐的像見了鬼。

鄭捷把殺人當成遊戲並不奇怪，因為鄭捷的父母先把生兒育女當遊戲。

關鍵字搜尋Google日誌關鍵字搜尋 關鍵字 webset41's新回應沒有新回應！ 累積|今日loading...... 阿豆腐新聞ddc作品區ddc的Blog二區  關於我加入好友我的相簿我的影音 全部展開|全部收合 201010110413何謂垂直入光(直射入光，Telecentric鏡頭,又稱為遠心鏡頭)?轉載 http://bbs.blueidea.com/thread-2979353-1-1.html 關鍵在於Telecentric 的翻譯。

我查閱了一些資料，攝影裡沒這麼一個概念。

Telecentric鏡頭,又稱為遠心鏡頭,其內部為遠心光學設計,亦即開口光圈在鏡頭的焦點位置上,可分為物體側,像側,或是兩側的遠心設計,主光線和光軸都是平行.  例如:物體側的遠心設計,從鏡頭接收自被測物的光線角度幾乎為0,所以就算物體有上下變化,尤其是高低的部分,幾乎不會有誤差產生,而在景深外的影像品質亦能維持,而且高低有差異的立體物體形狀,在相同視野的測試環境下,即使不在焦點位置內的惡劣環境下,仍能夠充分發揮高精度的影像量測. 最接近的概念是非球面鏡片的畸變矯正，但是看了圖示之後，發現不是這個意思。

http://www.surevision.com.tw/productaa01001.htm 參見這裡。

我給出的建議是：這應該是攝影之外的工業光學鏡頭（比如測量啊之類的，並非用於直接成像的），在鏡頭論壇上，也有叫做遠心鏡頭的，日本的說法是「焦闌鏡頭」，所以我覺得可以不翻譯，直接叫做Telecentric鏡頭 [本帖最後由闊靖於2010-4-523:22編輯] ------------------------------------------------------------------------------- 2.何謂直射入光,為何要直射? 首先我們要了解35MMFILM相機的光學構造,由於FILM跟CCD的構造,由於FILM的表面是平滑的,所以光射從那個方向射進去,只要沒有色散的射到FILM,那出來的效果都是良好的,然而CCD的構造,是不平滑的,每一個感光點之間都會有阻隔,只有直射才能完全受光。

I.FILM的感光 II.CCD非直射感光 III.CCD直射感光 直射入光帶來的好處如下: 1.照片更為立體 2.邊緣的成像良好,由其是在WIDEAngle的情況下。

為何非直射入光邊緣的成像會比較差呢,請參考下圖 I.傳統鏡頭沒有特別設計直射入光,邊緣的光線斜率比較高 II.4/3SYSTEM鏡頭特別設計直線入光,光線入射光度一致 -------------------------------------------------------------------------------   http://www.edmundoptics.com/technical-support/imaging/what-is-telecentricity/ WhatisTelecentricity? Telecentricityisaspecialpropertyofcertainmulti-elementlensdesignsinwhichthechiefraysforallpointsacrosstheobjectorimagearecollimated.Forexample,telecentricityoccurswhenthechiefraysareparalleltotheopticalaxis,inobjectand/orimagespace.Anotherwayofdescribingtelecentricityistostatethattheentrancepupiland/orexitpupilofthesystemislocatedatinfinity(seeFiguresAandB). FigureA Telecentriclensdrawingshowingdiscreteobjectpointsbeingimaged. FigureB Telecentriclensdrawingshowingchiefraysforeachobjectpoint.Notethatthechiefraysareparalleltotheopticalaxis. ADVANTAGES FigureC:Non-telecentric,TelecentricImagingresultsattheimageplaneofatelecentricandnon-telecentriclenssystem.Noticethetelecentricsystemeliminatesperspectivedistortion.   Thisdefinitionoftelecentricityleadstoanumberofquestions.Whyistelecentricitydesirable?Whatareitsadvantages,disadvantages,andlimitations?Formanyapplications,telecentricityisdesirablebecauseitprovidesnearlyconstantmagnificationoverarangeofworkingdistances,virtuallyeliminatingperspectiveangleerror.Thismeansthatobjectmovementdoesnotaffectimagemagnification. Inasystemwith objectspacetelecentricity,movementoftheobjecttowardorawayfromthelenswillnotresultintheimagegettingbiggerorsmaller,andanobjectwhichhasdepthorextentalongtheopticalaxiswillnotappearasifitistilted.Forexample,acylindricalobjectwhosecylindricalaxisisparalleltotheopticalaxiswillappeartobecircularintheimageplaneofatelecentriclens.Inanon-telecentriclensthissameobjectwilllookliketheLeaningTowerofPisa;thetopoftheobjectwillappeartobeelliptical,notcircular,andthesidewallswillbevisible(seeFigureC). Insystemswith imagespacetelecentricity,imageplanemovementstofocusorintentionallydefocusthesystemwillnotchangetheimagesize.Thispropertyisfundamentaltotoday'smicrolithographyindustrywheretolerancesonfeaturesizeareroutinelybelowatenthofamicron.Anadditionaladvantageofimagespacetelecentricityisthatitcanleadtoextremelyuniformimageplaneillumination.Thenormal cos4qfalloff inimageplaneilluminationfromtheopticalaxistotheedgeofthefieldisremoved,sinceallchiefrayshaveanangleofθ°withrespecttotheimageplane. DISADVANTAGES Thereareanumberofqualitiesinherentintelecentriclenseswhichmaybeconsidereddisadvantages.First,theopticalelementsintheregionoftelecentricity(imagesideorobjectside)tendtogrowinsize.Inthecaseofadoublytelecentricdesign(telecentricinbothobjectandimagespace),boththefrontandrearmostlensgroupsneedtobebiggerthantheobjectandimagerespectively.Thus,aonehundredmillimeterobjectorimageheightwillrequirealensofsignificantlylargeraperturediametertoprovideanunvignettedfieldofviewalongwithmechanicalmountingandretentionfeatures.ThisisillustratedinDiagram1and3(seebelow). Thegraphicsbelow(Figures1-3)depictexamplesofbothtelecentricandnon-telecentriclensesdesignedbyEdmundOptics.Theseexamplesinclude0.5Xrelaylenses(bothtelecentricandnon-telecentric)alongwithadoublytelecentric0.25XreductioncameralensformicrolithographicuseoperatingattheArFlaserline(0.193microns).     Diagram1Y-Zprofiledrawingofa0.5Xtelecentriclens(telecentriconobjectside)     Diagram2Y-Zprofiledrawingofa0.5Xnon-telecentriclens     Diagram3Doublytelecentric0.25XreductioncameralensformicrolithographicuseoperatingattheArFlaserline(0.193microns) Diagram1isaY-Zprofiledrawingofa0.5XtelecentriclensandDiagram2isaY-Zprofiledrawingofa0.5Xnon-telecentriclens.Itisimportanttonotethatbothlenseshavethesamelateralmagnification(0.5X),objectworkingdistance(125mm),objectheight(semi-diameter=11.0mm),andthesameworkingF/#(F/6).Thefrontlensgroupofthetelecentriclenshasadiameterofapproximately40mmwhilethatofthenon-telecentriclenshasadiameteroflessthan20mm-afactorofmorethantwotimessmaller. Aseconddisadvantageoftelecentricdesignsisthattheytendtobemorecomplexthannon-telecentricdesigns.ThisisillustratedbythedifferenceinelementcountwithinthetwodesignsshowninDiagram1and2.Thetelecentricdesignhassevenelementswhilethenon-telecentricdesigniscomprisedofonlyfive.Itshouldbepointedoutthatthenon-telecentriclensinDiagram2caneasilybemadetoperformatF/6(itwasoriginallydesignedtoworkatF/2)withonlyfourelements,threelessthanthetelecentriclens. Aswithmanyothersubjects,thereisacommonmisconceptionconcerningdepthoffieldandtelecentricity.Themisconceptionabouttelecentriclensesisthattheyhavealargerdepthoffieldthanordinarylenses. Realistically,telecentricitydoesnotimplylargedepthoffield,whichisonlydependentonF-numberandresolution.Withtelecentriclenses,objectsstillblurfartherawayfrombestfocus,buttheyblursymmetrically,whichcanbeusedtoone'sadvantage.Aslongastheobject'sfeaturesarewithinthetelecentricworkingdistance,themagnificationwillnotchange.Inotherwords,featuresclosertothelensdonotappearlargerthanthosefurthestaway. APPLICATIONUSES Thereareavarietyofapplicationsthatdependupon,orcanbenefitfrom,theuseoftelecentricoptics.TheseapplicationsincludeCCDbasedmeasurementsystems,metrologyequipment,andmicrolithographiccamerasystems. CCDbasedmeasurementsystemscanbeusedtomeasurethespacingand/orsizeofanumberofobjectsonanelectricalormechanicalcomponent.Theprecisemeasurementsofobjectsorfeatures,ortheirseparations,isaccomplishedthroughtheuseofmeasurementsoftware.Thistypeofsoftwareusescentroidingalgorithmsinthecalculationsofobjectseparationandsize.Atelecentriclensisidealforthisapplicationbecauseextendedobjectswillappearsymmetrical,whereastheimagefromanon-telecentricopticwillbeelliptical(seeFigureD).Theimprovementinmeasurementaccuracyresultingfromtheuseofatelecentriclenscanoftenmeanthedifferencebetweensuccessorfailure.   FigureDTelecentric,Non-telecentric Extendedobjectswillappearsymmetricalinatelecentricoptic,whereastheimagefromanon-telecentricopticwillbeelliptical. Manymetrologysystemsalsodependupontelecentricoptics.Aprofileprojectorisoneexampleofsuchasystem.Theprofileprojectorisusedtomeasureanobject,orafeaturewithinanobjectbyprojectinganimageoftheareaundertestontoascreen.Thisprojectedimageistheneithercomparedtoa"goldstandard"referenceatthepropermagnification,oritismeasureddirectlyanditsdimensionscomparedtothenominaldesignedpart.Thistypeofmeasurementabsolutelyrequiresthatmagnificationdoesnotchangewithobjectposition.Ifnottelecentric,thistypeofinstrumentwouldgiveadifferentmeasurementresulteachtimetheworkingdistancetotheobjectwaschanged.Thisisobviouslynotdesirableinaninstrumentdesignedtoprovideabsolutemeasurements. Microlithographiccamerasystemsalsodependuponthepropertyoftelecentricityintheirapplication.Theselenssystemsareoftendoublytelecentric-telecentricinbothimageandobjectspace.Theselenssystems,whichcancostinexcessofhundredsofthousandsofdollars,areusedinthemanufactureofintegratedcircuits(IC's).ThewafersorchipsuponwhichtheIC'sarefabricatedgothroughmanyimagingoperations,whichcreatethesurfacefeaturesonthewafer.Thesefeaturesareroutinelysub-microninsizeandgettingsmallerwitheverynewgenerationofmicrolithographicequipment.Thesizeofthesefeatures,alongwiththeirabsolutelocations,mustbecontrolledtosmallfractionsofamicron.ThisproblemisexacerbatedbytheoverlaynecessarywhennumerousresistexposuresandetchesarerequiredintheICproductionprocess.Maintainingaconstantmagnificationthroughtheuseoftelecentricopticsiscrucialinthiswholeprocess. SUMMARY Insummary,thisarticlehasdefinedthedifferencebetweentelecentricandnon-telecentricoptics.Ithasalsopresentedsomeofthebenefits,liabilitiesandlimitationsoftelecentricopticalsystems.Inaddition,anumberofapplicationsandsampledesignshavebeenpresented.Ifyouhaveanyquestionsoraneedforfurtherdiscussion,pleasefeelfreetocontactourApplicationsEngineeringdepartmentat(800)363-1992or online. DownloadPDFversionofthispage. (152KB)          ddc/Xuite日誌/回應(0)/引用(3)/好文轉寄沒有上一則|日誌首頁|沒有下一則回應