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1、PrinciplesofinterferometryNealJacksonUniversityofManchester,JodrellBankObservatoryneal.j.jackson@manchester.ac.ukInthisreviewIoutlinetheprinciplesofinterferometryanddescribehowtheseareputintopracticeinarangeofmoderninterferometrictelescopes.Thebasicphilosophyofthereviewistoemphasiseapictorial
2、approachtothesubject,ratherthandelveintodetailedmathematicalderivations.MuchmorerigoroustreatmentofinterferometrycanbefoundinThompson,Moran&Swenson(2001).Inaddition,theUSNationalRadioAstronomyObservatory(NRAO)hostsalectureserieseverythreeyearsininterferometry,publishedinTaylor,Carilli&Perley(
3、1998).Throughout,Iconcentrateonapplicationsofinterferometrytointerferom-etersatlong(wave-regime)wavelengths,withoccasionalexcursionsintometh-odsusedinthenewgenerationofopticalinterferometers.Thefinalsectionisanoverviewofcurrentinterferometersworkinginthemetre-to-millimetreband.Theprinciplesbeh
4、indinterferometersatallwavebands,however,areverysimilar,includingallofsection1andmostofsection2.ArecentfullandcomplementaryreviewofopticalinterferometryisgivenbyMonnier(2003),andotherreviewsintheseproceedingscovertheVLTinterferometerindetail.1Basics:Young’sslitsandFouriertransforms1.1Young’ss
5、litsInterferometrybeginswiththeYoung’sslitsfringepattern(Fig.1).Withasinglepointsourceemittingcoherentradiation,interferencefringesareob-served,withconstructiveanddestructiveinterferenceobservedastherelativedelayofthetwointerferingrayschanges;theseparationofthefringesisλ/d,thewavelengthofthel
6、ightdividedbytheslitseparation.Ifthesourceismadewider(Fig.1b),wecanthinkofitasasequenceofpointsourceseachofwhichemitradiationwhichisuncorrelatedwiththeemissionfromtheothers.Itfollowsthatthetotalinterferenceintensitypat-ternisthesumoftheindividualpatterns.Sinceanangulardisplacementin2NealJacks
7、onabcdFig.1.Young’sslitsinvarioussituations.Ineachpanelthesourceisshownontheleft,andontherightoftheslitareshownthefringepatternsseparatelyforeachpartofthesourceandthentheaddedfringepattern.a:Thebasictwo-slitpattern,showingfringesanangulardist