马尔文激光粒度仪简介

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1、laParticlesizeanalysis-Laserdiffractionmethods(ISO-13320-1)IntroductionLaserdiffractionmethodsarenowadayswidelyusedforparticlesizinginmanydifferentapplications.Thesuccessofthetechniqueisbasedonthetactthatitcanbeappliedtovariouskindsofparticulatesystems,isfastandcanbeautoma

2、tedandthatavarietyofcommercialinstrumentsisavailable.Nevertheless,theproperuseoftheinstrumentandtheinterpretationoftheresultsrequirethenecessarycaution.Therefore,thereisaneedforestablishinganinternationalstandardforparticlesizeanalysisbylaserdiffractionmethods.Itspurposeis

3、toprovideamethodologyforadequatequalitycontrolinparticlesizeanalysis.Historically,thelaserdiffractiontechniquestartedbytakingonlyscatteringatsmallanglesintoconsiderationand,thus,hasbeenknownbythefollowingnames:-fraunhoferdiffraction;-(near-)forwardlightscattering;-low-angl

4、elaserlightscattering(LALLS).However,thetechniquehasbeenbroadenedtoincludelightscatteringinawiderangularrangeandapplicationoftheMietheoryinadditiontoapproximatingtheoriessuchasFraunhoferandanomalousdiffraction.Thelaserdiffractiontechniqueisbasedonthephenomenonthatparticles

5、scatterlightinalldirectionswithanintensitypatternthatisdependentonparticlesize.Allpresentinstrumentsassumeasphericalshapefortheparticle.Figure1illustratesthecharacteristicsofsingleparticlescatteringpatterns:alternationofhighandlowintensities,withpatternsthatextendforsmalle

6、rparticlestowideranglesthanforlargerparticles[2-7,10,15inthebibliography].Withincertainlimitsthescatteringpatternofanensembleofparticlesisidenticaltothesumoftheindividualscatteringpatternsofallparticlespresent.Byusinganopticalmodeltocomputescatteringforunitvolumesofparticl

7、esinselectedsizeclassesandamathematicaldeconvolutionprocedure,avolumetricparticlesizedistributioniscalculated,thescatteringpatternofwhichfitsbestwiththemeasuredpattern(seealsoannexA).Atypicaldiffractioninstrumentconsistsofalightbeam(usuallyalaser),aparticulatedispersingdev

8、ice,adetectorformeasuringthescatteringpatternandacomputerforbothcontroloftheinstrumentand