ManualM7LL/M70LLLaser‐Sensors
HB‐M7LL‐M70LL‐E.docpage6of23V20130301
MELMikroelektronikGmbH,BreslauerStr.2,85386Eching/Germanywww.MELSensor.com
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Objektoberfläche
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Athicknessmeasurementsystemismadeoftwosensorsystems
withanadd‐onoptionthicknessmeasurement.Thesensorsare
directedontheupperandlowersurfaceoftheobject.Theslave
sensor(usuallyatbottom)sendshisdistancesignaltothemaster
sensor.Themasteroutputsthethicknessvaluewhichisthesumof
bothsensorsignals.
Athicknessmeasurementsystemismadeoftwosensorsystems
withanadd‐onoptionthicknessmeasurement.Thesensorsare
directedontheupperandlowersurfaceoftheobject.Theslave
sensor(usuallyatbottom)sendshisdistancesignaltothemaster
sensor.Themasteroutputsthethicknessvaluewhichisthesumof
bothsensorsignals.
Theoutputvoltageofthethicknesssignalis0…10Vfortherangeof
bothsensors.
Theoutputvoltageofthethicknesssignalis0…10Vfortherangeof
bothsensors.
Eachsensorheadhasitsownelectronicsystem(bluebox).Eachsensorheadhasitsownelectronicsystem(bluebox).
Measurement errorsMeasurement errors
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Objectscouldbevariousmaterialslikemetal,plastic,ceramics,
rubberandpaper.WithhighlyreflectivematerialsorliquidsitshouldbetestedfortheindividualmaterialiftheM7LLcouldmeasure
thissurface.
Objectscouldbevariousmaterialslikemetal,plastic,ceramics,
rubberandpaper.WithhighlyreflectivematerialsorliquidsitshouldbetestedfortheindividualmaterialiftheM7LLcouldmeasure
thissurface.
Onpartiallytransparentplasticorblearyliquidsthelaserbeampenetratesintothe“materialsurface”beforethediffusereflected
lightissentbackfromthesurface.Therealmeasureddistanceneedstobecorrectedbyafactorof“penetrationdepth”.
Onpartiallytransparentplasticorblearyliquidsthelaserbeampenetratesintothe“materialsurface”beforethediffusereflected
lightissentbackfromthesurface.Therealmeasureddistanceneedstobecorrectedbyafactorof“penetrationdepth”.
Scratches in the measurement spotScratches in the measurement spot
Ascratchacrossthelensaxismaycausestrongerreflections,withamaximumofenergyatthesideofthespot.Thiswillaffectthe
distanceinformation.Inthesametimetheintensityvaluewillchange.Fortestingonscratchesthismethodmaybemorehelpful
thanmonitoringthepuredistanceinformation.
Ascratchacrossthelensaxismaycausestrongerreflections,withamaximumofenergyatthesideofthespot.Thiswillaffectthe
distanceinformation.Inthesametimetheintensityvaluewillchange.Fortestingonscratchesthismethodmaybemorehelpful
thanmonitoringthepuredistanceinformation.
Whentheobjectismoving,theaverage(integrated)valuewillbeconstantwhenmovingoverthescratch.Thismeans:thepositive
andnegativeedgeofthesignalwillcompensateeachother.
Whentheobjectismoving,theaverage(integrated)valuewillbeconstantwhenmovingoverthescratch.Thismeans:thepositive
andnegativeedgeofthesignalwillcompensateeachother.
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Whenhighlyreflectiveobjectsareclosetothemeasurementspot,mirroringthelaserlightintothereceiveroptics,then
measurementerrorsmaybecaused.
Whenhighlyreflectiveobjectsareclosetothemeasurementspot,mirroringthelaserlightintothereceiveroptics,then
measurementerrorsmaybecaused.
Objectswithdiffusereflectivitymaynotcausethesameerrors.Whenthemirroringsurfaceisoutsideofrange,theresidualerror
maybeupto2%.Duetothesmallerspotsize,straylighterrorissmallerforLasersensorsthanforLEDsensors.
Objectswithdiffusereflectivitymaynotcausethesameerrors.Whenthemirroringsurfaceisoutsideofrange,theresidualerror
maybeupto2%.Duetothesmallerspotsize,straylighterrorissmallerforLasersensorsthanforLEDsensors.
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Whendistancemeasurementismadeinaplacewherethe
materialsurfaceischangingfromdiffusereflectingtomirroring
materialandthereforethereflectivityischangingstrongly,
duringthetransitmeasurementerrorsmayoccur.The
maximumoftheintensityisnotinthecenterofthespot.
Whendistancemeasurementismadeinaplacewherethe
materialsurfaceischangingfromdiffusereflectingtomirroring
materialandthereforethereflectivityischangingstrongly,
duringthetransitmeasurementerrorsmayoccur.The
maximumoftheintensityisnotinthecenterofthespot.
IndirectionA,theerrorisminimal;indirectionBitismaximal.IndirectionA,theerrorisminimal;indirectionBitismaximal.
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Thesensorsareequippedwithaautomaticintensityregulation
formatchingtomoreorlessreflectingobjects.Whenthe
surfaceischangingduringmeasurement,theintensityiskept
constantbytheregulationsystem.
Thesensorsareequippedwithaautomaticintensityregulation
formatchingtomoreorlessreflectingobjects.Whenthe
surfaceischangingduringmeasurement,theintensityiskept
constantbytheregulationsystem.
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Themeasurementhasasmalldependencyfrominclination
angle.RotationonaxisAupto30°androtationonaxisBupto
15°donotcausebigmeasurementerror.Measurementsonasurfacewithgooddiffusereflectionarelessdependingonanglethan
measurementsonmirroringsurfaces.(Seethepictureabove).
Themeasurementhasasmalldependencyfrominclination
angle.RotationonaxisAupto30°androtationonaxisBupto
15°donotcausebigmeasurementerror.Measurementsonasurfacewithgooddiffusereflectionarelessdependingonanglethan
measurementsonmirroringsurfaces.(Seethepictureabove).
Themeasurementerrorshowsupasachangeintheratioofoutputvoltage/distance.Whentheerrorisconstant,aspecial
calibrationcouldeliminatetheerror.
Themeasurementerrorshowsupasachangeintheratioofoutputvoltage/distance.Whentheerrorisconstant,aspecial
calibrationcouldeliminatetheerror.
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