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时间:2020-06-19
《如何挑选合适的光管匀光棒.doc》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、HowtoSelecttheRightLightPipeHomogenizingRodMuchlikeopticalfibers,lightpipehomogenizingrodsutilizetotalinternalreflection(TIR)totransmitlightfromtheentrancetotheexitofthelightpipe.Thesubstrate’srefractiveindexistheonlyfactorthatinfluencesthelightpipe’scriticalangle,whichdefi
2、nestheangleofacceptanceatwhichTIRwilloccur.LightpipesdesignedspecificallyforhighNA,standardNA,andlowNAlightsourceswillhavethesameacceptanceangleifdesignedwiththesamesubstrate.Thecriticalangle(θc)calculatedusingEquation1:(1)InthecaseofanN-BK7lightpipe,theindexofrefractionatH
3、elium’sd-lineof587.9nmis1.517,resultinginaθcof41°.Iftheincidentangleisgreaterthanθc,TIRwilloccurandlightwillbetransmittedthroughoutthelightpipe(Figure1).Sincelightraysenteralightpipeatavarietyofincidentangles,thenumberofreflectionsinsidethelightpipediffersfromraytoray.Thesm
4、allestincidentangle,whichisequaltoθc,willhavemorereflectionsthanlightenteringatanincidentanglethatismanytimeslargerthanθcwithinthesamelengthlightpipe(Figure2).DuetolowNAlightsourceshavingalargernumberofraysgreaterthanθcthanhighNAlightsources,lowNAlightpipesarelongerthanhigh
5、NAlightpipes,andarerecommendedforlightsourceswithnarrowbeamdivergence.Note:Lightpipesarenotdesignedforusewithcollimatedlasersources.Tohomogenizecollimatedlightsources,MicrolensArraysorflattoplaserbeamshapersarerecommended.Lightpipesareidealforhomogenizingpolychromaticsource
6、sthatemitnon-collimatedlight.Figure1:TotalInternalReflection(TIR)inaLightPipeHomogenizingRodFigure2:SmallIncidentAnglesHaveMoreReflectionsthanLargeIncidentAngles
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