光学显微镜应用：暗场照明.doc

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1、OpticalMicroscopyApplication:DarkfieldIlluminationDarkfieldilluminationisatechniqueinoptical microscopy thateliminatesscatteredlightfromthesampleimage.Thisyieldsanimagewithadarkbackgroundaroundthespecimen,andisessentiallythecompleteoppositeofthebrightfieldilluminationtechnique.Theprimaryimagingg

2、oalofthedarkfieldilluminationtechniqueistoenhancethecontrastofanunstainedsample,whichisincrediblypowerful,yetsimple,forlivecellularanalysisorsamplesthathavenotgonethroughthestainingprocess.IMAGEAPPEARANCEAtypicaldarkfield illumination imagehasawhite/brightspecimenwithadarkbackgroundandenvironmen

3、tfillingtheimage.Thisistheexactoppositeofabrightfieldilluminationimage,andisusefulforunstainedspecimensorimagesthatrequireincreasedcontrast.Theadvantagewithusingdarkfieldilluminationisthatunstainedspecimenscanremainaliveandvital,whereastheirbrightfieldcounterpartsmustbetreatedandarenolongeractiv

4、e.Also,itispossibletoacquiremorequalitativeresultswiththistechniquethroughlivecellularanalysis.Foradditionalinformationonthebrightfieldtechnique,pleaseread OpticalMicroscopyApplication:BrightfieldIllumination.Figure1: DarkfieldIlluminationImageofTissuePaperFigure2: OpticalPathforDarkfieldIllumin

5、ationTECHNICALDETAILSThelightpathofthedarkfield illumination techniqueistypicallyappliedtoanuprightmicroscope,asseeninFigure2.Thelightpathconsistsofthreekeycomponents.1.LightSource: entersthemicroscopeandhitsthe darkfieldpatchstop,whichisadiscusedtoblocklightfromenteringthecondenserandleavesacir

6、cularringofillumination.2.CondenserLens: collectsouterringofilluminationandfocusesitonthesample.3.ObjectiveLens: lighthitsthesample,andistransmittedorscatteredfromit.Scatteredlightenterstheobjectivelens,whereastransmittedlightisnotcollectedbythelens.The directilluminationblock assistsinthisstep.

7、Additionalopticalmicroscopyapplicationsinclude brightfieldillumination, phasecontrast,fluorescence,and differentialinterferencecontrast.