광음향초음파송신기희소어레이를활용한3차원이미징시스템개발

Abstract

Ultrasoundimagingisusedinmanyfieldssuchasbio-medical,non-destructive,andautomotivesensorsbyusingitsnon-invasiveproperties.Ultrasounddiagnosticequipmentisanessentialdevicefordiagnosingconditionsinsidethehumanbodyinthebio-medicalfield.commercialequipmentgenerallyperforms2-Dimagingwithanultrasonicprobecomposedofa1-Darray.Inrecentyears,thedemandfor3Dimagingisincreasingformoreprecisediagnosticandexaminationofvarioussymptoms.A2-Darrayisrequiredforreal-time3-Dimaging.Forthispurpose,a2-DarraycomposedofCMUTsorPMUTshasemerged.Thelargerthearraysize,thebetterintermsofresolution,butbecausethenumberofchannelsincreases,ittakesalotoftimeandmoneytoproduceit.Unlikeconventionalelectricultrasonictransducers,light-inducedultrasoundusesalasertotransmitultrasound.Thismethodiseasytomanufacturebecauseitdoesnotrequireahighvoltagepulser.Butithasthedisadvantageoftakingalongtimetomeasure.Thispaperproposesa3-Dimagingsystemusingalight-inducedultrasoundsparsearrayasatransmittertocompensatefortheseshortcomings. Asparsearraywasdesignedthatwasoptimizedfornoiseutilizingasimulatedannealing.Optimizesthearrangementofsparsearraystoachieveimagequalitysimilartodensearrays.ACMUTwasdesignedfora2-Darrayandcharacteristicswerecalculatedthroughfiniteelementanalysis.LoadresistorwascalculatedthatmodeledthenoisethatmightoccurintheCMUT,resultinginhighsensitivitytonoise.Afterimagingthepointspreadfunction,theperformancewasevaluatedasIntegratedSidelobeRatio(ISLR).TheeffectofnoiseaccordingtothenumberofchannelswascomparedbycalculatingtheISLRaccordingtothepresenceorabsenceofnoise.Weanalyzedtheoptimalnumberofchannelstominimizetheeffectofnoise. Light-inducedultrasoundtransmittershavebeenmanufacturedinvariousways.Acarbonnanotubelayerwasdepositedonaplate-shapedsubstratefor2-Dscanningbymethodssuchasbrushtouch,dipcoatingandspincoating.Byusingapulsedlaser,characteristicsoflight-inducedultrasoundtransmittersforeachmanufacturingmethodandcharacteristicsaccordingtothelaserbeamwidthweremeasured.AdeviceinwhichaCNT-PDMScompositewasdepositedonaglasssubstratebyspincoatingwasmeasuredwithahighcenterfrequency,widebandwidth,andthehighestsoundpressure.thissamplewasusedina3-Dimagingtest.Thefeasibilityofthesystemwasdemonstratedby3-Dimagingofcopperwiresandchickenhearts. Thenumberofimagingshotspersecondofphotoacousticultrasoundisdeterminedbythreefactors:thenumberofmeasurementpoints,thenumberofrepetitionspersecondofapulsedlaser,andtheimagereconstructiontime.Therepetitionrateofalaserandimagereconstructiontimearedeterminedbyhardwareperformance.Therefore,wereducedthenumberofmeasurementpointsbyapplyingasparsearraytolight-inducedultrasoundtransmitter.Basedonthelight-inducedultrasoundsignalmeasuredintheexperiment,theminimumnumberofchannelswasdetermined,andoptimizationwasperformedconsideringnoise.Previously,theperformanceofthesystemwasverifiedthroughcopperwireexperimentsandsuccessfullyimaged.Comparedwith128channels,imagingwaspossibleataspeedofabout37.5timesfaster,andiffurtherresearchonoptimizationisconducted,weexpecttobeabletoimagefaster.