3. Subwavelength Imaging by Arrays of Metallic Rods

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1、FilippoCapolino/ApplicationsofMetamaterials_CFinalsPage--#3SubwavelengthImagingbyArraysofMetallicRodsPavelA.Belov.Introduction.........................................-QueenMaryUniversityofLondon.WireMediumLens...................................-M

2、árioG.Silveirinha.TransmissionandReflectionCharacteristicsofWireMediumSlabs..................................-UniversityofCoimbraAnalyticalModeling●ParametricStudyofReflectionandTransmissionPropertiesConstantinR.Simovski.MagnifyingandDemagnifyingLenseswithHelsinkiUn

3、iversityofTechnologySuper-Resolution.....................................-YangHao.ImagingatTerahertzFrequenciesandBeyond.......-QueenMaryUniversityofLondonReferences.................................................-3.1IntroductionLens-basedimagingdevicessuchasc

4、onventionalmicroscopescannotprovideresolutionbetterthanλ/,whereλisthewavelengthofradiation.Thisrestrictionisknownasthediffractionlimitandholdsirrespectivelyofthefrequencyofoperation—frommicrowavefrequenciesuptothevisiblerange.Conventionallensesoperateonlywiththefar-field

5、ofthesource,whichisformedbyprop-agatingspatialharmonics.Theinformationrelatedtothenear-fieldofthesourceistransportedbyevanescentspatialharmonics,whichexhibitexponentialdecayinallnaturalmaterialsaswellasinfreespace.Forthisreason,thesubwavelengthdetailsofthenear-fieldarenot

6、directlyaccessiblewithconventionalimagingsystems.Inpractice,thenear-fieldcanbescanned,pointbypoint,usingsmallnear-fieldprobes.However,scanningnear-fieldmicroscopyisaratherslowprocess,andthuslensesthatmayenablethesimultaneousimagingofthewholeregionofinterestwithsuper-resol

7、utionwouldbeextremelyuseful.Thediffractionlimitcanbesurpassedonlyifoneadoptsaconceptuallydifferentimagingtech-nique.Inordertoobtainimagingwithsubwavelengthresolution,itmaybenecessarytooverstepbeyondthefrontiersofnaturallyavailablematerialsandtousespeciallyengineeredartifi

8、cialmediawithelectromagneticpropertiesnotreadilyavailableinnature.Inrecentyears,severaltechnique