March2010IntroductionofLaserScannerOpticsBackViewofLaservs.BarcodeVLD:650nm5mwHeatSinkYokeLens(f=4mm)BarrelVLDComponentsWaistoftheVLDLaserDiodeLensApertureoftheBarrelLaserBeamBeamProfileWhyweneedtopayattentiontoBeamProfile?BeamProfilevs.DOFProfileoftheLaserBeamDepthOfFieldBeamProfileElongationofLaserSpotHowtoDecidetheBeamProfile?ScanDirection:VLDtypeBarrelaperture(0.040”)LensDistancebetweenfromVLDtolensCrossDirection:FoldingmirrorCylindricallensHowtomeasureVLDbeamprofile?BeamscanRonchitestHowRonchiTestWorks?FocustoofarFocustoonearFocuscorrectRochiCheckingFocusDistanceLocatebeamwaistatornearcenterrulingEqualizesignalsfrom1stand3rdwheelsChecktranslationdistanceagainstspecIfwaististoofarfromnominallocation,VLDfailsCollectorMirrorFoldedmirror:ReflectLaserbeam;Elongatethelaserbeam;Collectmirror:CollectingthelightreturnedPhotodiodeFilterPhotodiodeImagingspotItisafunctionoftherelativesizesofthedetectorandtheimageatthedetector.Thetheoreticalrangeis0%to100%.ImageCollectionFactorBand-passfilterTheopticallayoutforsinglelinemoduleFlipperCollectmirrorVLDPD&CanFoldedmirrorLaserbeamPCBSingle-lineLaserbeamandlightreflectedWhat’sspeedofthelaserbeamacrossthebarcode?Single-linescanpatterngenerationIncidentLaserBeamTime=t1Time=t2Time=t1Time=t2Oscillatingmirror(Flipper)36Hz=72scans/second50Hz=100scans/second90Hz=180scans/second(TopView)SpotSpeed角速度:ω=θ/t(rad/s)線速度:ν=ω*R

(m/s)SpotSpeed=線速度(m/s)

Frequency=Barwidth/Spotspeed(Hz)Whyweneedomnidirectional?Reason1FrontBackLeftRightAtleast3scanningsides,possibly6sides.scannerReason2Whyweneedomnidirectional?Omni-direopticallayoutandstructureMirrorseriesIVLDPolygonMotorPhotodiodeCollectorMirrorseriesIINumberofscanlines=sidesofpolygon*setsofmirrorRotatingMirror(Polygon)StationaryMirrors(Cluster)Time=t1Time=t2Omni-directionalScanPatternGenerationRotatingmirror(Polygon)5000rpm,6000rpmfacetsonrotatingpolygon4Stationarymi