beam steering devices光束转向装置

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1、BEAMSTEERINGDEVICEST.Kranjc1andJ.Pirš2,1FacultyofEducation,UniversityofLjubljana,Slovenia2Institute“JožefStefan”,Ljubljana,SloveniaCorrespondingauthor’se-mail:tomaz.kranjc@pef.uni-lj.si1IntroductionSomeinterestingtopicsconcerningphysicsofliquidcrystals(LC)andtheirtechnologicalusefulnessmay

2、bepresentedinphysicsinstructionalreadyinthesecondaryschoolandinintroductoryuniversitycourses.Theymayservetointroducesomeimportantphysicsconcepts(atomicstructureandmicroscopicconfigurations,orderandorderparameters,symmetry,thermalmotionetc.)inordertoillustratephysicalpropertiesofmatterandto

3、showhowphysicslawscanbeusedandappliedtopracticalsituations.LCsareparticularlyappropriatetodemonstrateseveralopticalpropertiesofmatterandunderlyingphysicsprinciples.Forexample,inmatchingvariouslightbeams,thedesiredopticalpathdifferencesmaybeachievedeitherbyadjustingthethicknessofanopticalme

4、diumoritsindexorrefraction.TheindexofrefractionofLCscanbeeasilychangedandproperlyadjusted.AnimportantpartofmodernopticaltechnologiesisbasedonopticalpropertiesofLCswhichinturndependonaspecialinternalorderofLCmaterialaswellasingenuoustechnicalsolutions.Inopticalcommunicationsoververylongdist

5、ances,opticalbeamswithverysmalldivergencearerequired.Furthermore,withhighlycollimatedlightbeamsanultra-precisionalignmentisnecessary.Atpresent,typicalhighprecisionopto-mechanicaldevicesuseveryexpensiveopticalelements(precision(“l/10”)mirrors,galvo-motorsandotherprecisionmicro-mechanicalpos

6、itioningdevices).Suchelementsareexpensiveandtheirtimeresponseisratherslow(whichisinadequateformanyapplications).However,newtechnologicalsolutionsareemerging,basedonanentirelydifferentconcept,whichdoesnotrequireexpensiveprecisionmechanicalandopticalcomponents.Thesenewprecisionbeamsteeringde

7、vicesarebasedontheuseofmatrixarraysofreflectivetype“micro”LClightmodulators(~5μm×5μm)usingstandardLConsilicondisplaytechnology(LiquidCrystalOnSilicon–LCOS).Byaproperelectricallycontrolledadjustmentoftheeffective“opticalpathvalue”foreachoftheLCmatrixelementsone