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1、Diffraction?Interferencewithmorethan2beams–3,4,5beams–Largenumberofbeams?Diffractiongratings–Equation–Uses?Diffractionbyanaperture–Huygen’sprincipleagain,Fresnelzones,Arago’sspot–Qualitativeeffects,changeswithpropagationdistance–Fresnelnumberagain–Imagingwithanopticalsystem,nearandfarfield–Fraunhofe
2、rdiffractionofslitsandcircularapertures–Resolutionofopticalsystems?DiffractionofalaserbeamLASERS51April03InterferencefrommultipleaperturesLBrightfringeswhenOPD=nλ40xnLλdx=dIntensitysourceOPDtwoslitspositiononscreenscreenCompletedestructiveinterferencehalfwaybetweenOPD1OPD1=nλ,OPD2=2nλOPD2allthreewav
3、esinterfereconstructively40dIntensitysourcethreepositiononscreenequallyspacedslitsscreenOPD2=nλ,noddouterslitsconstructivelyinterferemiddleslitgivessecondarymaximaLASERS51April03Diffractionfrommultipleapertures?Fringesnotsinusoidalformorethantwoslits2slits?Mainpeakgetsnarrower–Centerlocationobeyssam
4、e3slitsequation?Secondarymaximaappear4slitsbetweenmainpeaks–Themoreslits,themore5slitssecondarymaxima–Themoreslits,theweakerthesecondarymaximabecome?Diffractiongrating–manyslits,verynarrowspacing–Mainpeaksbecomenarrowandwidelyspaced–SecondarypeaksaretoosmalltoobserveLASERS51April03Reflectionandtrans
5、missiongratings?Transmissiongrating–manycloselyspacedslits?Reflectiongrating–manycloselyspacedreflectingregionsInputscreenwavepathlengthtoInputobservationpointopaqueHuygenswavetransmittingwaveletsopeningwaveletspathlengthtoobservationpointscreenabsorbingreflectingTransmissiongratingReflectiongrating
6、LASERS51April03Gratingequation–transmissiongratingwithnormalincidenceDiffractedlightΘdpλinputsinθ=dl?ΘisangleofdiffractedrayExceptfornotmakingadsmallangleapproximation,?λiswavelengththisisidenticaltoformula?lisspacingbetweenslitsforlocationofmaximainmultipleslitproblemearlier?pisorderofdiffractionLA
7、SERS51April03Diffractiongratings–generalincidenceangle?Gratingequationpλsinθ?sinθ=dill=distancebetweengrooves(gratingspacing)ΘiΘi=incidenceangle(measuredfromnormal)ΘdΘd=diffractionangle(measuredfromno
