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1、Laser SafetySeptember2014LiverpoolUniversityContentsBasicsHealth&SafetyLegislationLaserClassificationLasersafetyLabellingLaserSafetyProceduresatLiverpoolPracticalLaserSafetyHazardEvaluation&RiskAssessmentThe lasing mediumA lasing medium is a material which has an atomic or molecular structure which
2、produces a coherent beam of light when sufficient energy is supplied. The energy supplied (usually electrical energy) is converted into laser light and heat.The medium can be a solid (e.g. ruby), a liquid (e.g. organic dye) or a gas (e.g. carbon dioxide).The performance of a laser is largely governe
3、d by the choice of material used as the lasing medium.SimplediagramofalasertubeBeamLasing mediumMirrorsEnergy input e.g. high voltageXTubecontaininglasingmediumXMirrorsateitherendXPowersupplyX“Pumping”-electricalorlightXCoolingsystemXDeliverysystemDesignofalaserUnitsWavelengthorcolournanometres1nm=1
4、/1000000000mPower-WattsEnergy-JoulesPulselength-secondsmsmillisecond1/1000ssmicrosecond1/1000000snsnanosecond1/1000000000spspicosecond1/1000000000000sfsfemtosecond1/1000000000000000sTypesoflaseremissionXContinuouswave(CW)XFreerunning(ms,s)XTriggeredpulse:ns,ps,fsBeamdeliveryXDirectbeamXHollowwavegui
5、deXArticulatedarmXOpticalfibreDirectbeamArticulatedarmDivergingbeamfromafibreFocusingalaserbeamvThebeamfromtheendofafibrewilldivergevAlaserbeamcanbefocusedbyalenstogiveaveryhighpoweroverasmallarea-comparewithmagnifyingthesunsraysvCanleadtoveryhazardoussituations.XFor a continuous beam:POWER DENSITY
6、= Power/Area i.e Watts per square metre:W.m-2XOr for a laser pulse:ENERGY DENSITY = Energy/Areai.e Joules per square metre:J.m-2When a laser beam is focused, there will be a greater effect where the power is concentrated over a small area:Devicemalfunctions-whatcangowrong?Shutterjammedopen.Brokenfib
7、re.Unprotectedexposureswitch.Laserlightleakage.Wrongoutputtoohighorlow.Failuretoterminate.Aimbeamnotco-incidentwithmainbeamProblemswithexperimentalset-up.InteractionsoflightontissueXTissuetypeXWavelengthXPower/energydensityXDurationofpulseXPulserepetitionrateXMedicalðnichistoryofpersonXEtcDepend
8、on:ThefourmaineffectsXThermalXheatingupto800oCXMechanicalXshockwavesbyhighenergydensities.XPhotoablationXbondbreakinge.g.UV(Excimer)lasersXPhotochemicalXchemicalreactionbutnoheatinge.g.PDT.So it is important to keep the aperture at the right distance from the tissue, in order to get the desired powe
9、r density and the intended effectTHERMAL EFFECTS50oC100oC70oC300oC Carbonisation 50oCDivergence 15oHarmfuleffectsofexposuretolaserXCorneaXLensXRetinaXBurnsXPhotochemicalEyeSkinPregnancy - NO HAZARD FOR STAFFAccidental laser burn to the retinaIGNORANCECOMPLACENCYLaser Safety - LegislationLegalRespons
10、ibilitiesforemployer&employeeHealth&SafetyatWorkActWorkEquipmentRegulationsManagementRegulationsriskassessmentsControl of Artificial Optical Radiation at Work Regulations 2010 (AOR Regs)MandatoryRulesforUniversityStaffandStudentsGuidanceBritishStandardBSEN60825-1(2007)Health & Safety Law Health&Safe
11、tyatWorkAct1974TheactplacesdutiesonbothemployersandemployeesItiscriminallawandcanbeenforcedagainstpersonsandorganisations.Theactcanbesummedupas;Employersduty:Tosafeguardsofarasreasonablypracticablethehealth,safetyandwelfareofemployeesandothersaffectedbythework.Employeesduty:Totakereasonablecareforth
12、esafetyofthemselvesandothers;tocooperate;nottoberecklessWork Equipment RegulationsAllequipmentmustbesuitableMaintainedinanefficientstateMaintenancerecordedRestrictedtotrainedusersUsersmusthaveinformationandtrainingAccesspreventedtodangerouspartsAdequatecontrolsandlock-offsSuitableenvironmentManageme
13、nt Regulations (Risk Assessment)1999ManagementRegulations(HSAW)Regulation3.Everyemployershallmakeasufficientassessmentoftheriskatworkto:EmployeesOthersaffectedRecordskeptof:RiskassessmentSafeMethodsofWork(LocalRules)ReviewandupdateasnecessaryBritish Standard for Laser Safety (Web: http:/www.hpa.org.
14、uk/radiation/)EN60825-1:2007-SafetyofLaserProductsEquipmentclassification,requirementsandusersguideEN60825-2:2004 - SafetyofLaserProductsSafetyofopticalfibercommunicationequipmentPD IEC TR 60825-14:2004 - SafetyofLaserProductsAUsersGuideObjectives of BS Laser Safety StandardsToprotectpersonsfromlase
15、rradiationbyindicatingsafe working leveloflaserradiationTointroduceasystemofclassificationoflasers&laserproductsaccordingtodegreeofhazardTolaydownrequirementsforbothuser&manufacturertoestablishprocedures&supplyinformationsothatprecautionscanbetakenToensurewarningoflaserhazardsbysigns, labels & instr
16、uctionsTominimiseaccessibleradiation,andcontrolradiationbyprotectivefeaturesandcontrol measuresToprotectpersonsfromother(non radiation) hazardsassociatedwithlasersBS EN 60825-1 Safety Standard (Web: http:/www.hpa.org.uk/radiation/)EN60825-1providestablesofAccessible Emission Limit (AEL)foreachclasso
17、flaser:Maximumoutputforgivenwavelength&emissiondurationLaserproductsinclude:pactdiscplayerisalaserproductbecauseitcontainsalasersystemNB:Lightemittingdiodes(LEDs)areimpliedbylaserinBSLaser ClassificationToclassifyalaser,needtoknow:LaserwavelengthMaximumpower(orpulseenergy)ExposuredurationViewingcond
18、itionsEachlaserclasshasasetofsafetycontrolmeasuresthatmanufacturersandusersmustobeyClassificationoflaserdeterminedby:AccessibleEmissionLimit(AEL)MaximumleveloflaserradiationthatthelasercanemitoveritsfullrangeofcapabilityduringoperationatanytimeafteritsmanufactureClass1Safeunderreasonablyforeseeableo
19、perationClass1MGenerallysafesomeprecautionsmayberequiredClass2Visiblelightatlowpower,blinklimitsriskClass2MUVorIRlightatlowpower,generallysafe-someprecautionsmayberequiredClass3RSafeforviewingwithunaidedeye,(i.e.notbytelescopeetc)Class3BViewingbeamhazardous,diffusereflectionssafeClass4Hazardousunder
20、allconditions,eyesandskinLaser ClassificationVIDEO CLIP 1 Laser ClassificationClass 1(Safe)Safeunderreasonablyforeseeableconditionsofoperation,includingtheuseofopticalinstrumentsforintrabeamviewingClass1AEL1mWMaycontainhighpowerlaserwithhigherclassificationEffectiveengineeringcontrolsusedtorestrictr
21、outineexposuretoClass1AELCompactdiscplayerlaserprintersCDROMplayersHANDOUTClass 1MNewclassfornewEN60825-2regulationstodealwithfibrecomms&LEDs302.5nmto4mGenerally“safe”asClass1Safeexceptfordivergingorlargeareabeamswhencollecting/focussingopticsusedHANDOUTClass 2 (Low Power)Maxoutput-1mWVisibleonly:40
22、0nmto700nmBlinkresponseofeyeaffordsprotectionOKevenforusewithopticalinstrumentsE.g:SupermarketscannerHeNelaserinteachinglabLaserdiodeinteachinglabClass2MOKunlesscollectingorfocusingopticsusedHANDOUTClass 3R (Low/Medium Power)Maxoutput5mWandirradiance MPERestrictedtoauthorisedpersonsByphysicalmeans:w
23、alls,doors,locks,numberpadsVIDEO CLIP 2 Control MeasuresPersonal Protective EquipmentLasersafetygogglesFireresistantclothingandglovesUsed when:RiskofinjuryorharmcannotbesuitablyminimisedbyengineeringcontrolsetcProtectionisrequiredagainsthazardsassociatedwithlasers(noise,chemicaletc)PPEisrequiredforC
24、lass3Band4Protectiveclothingwhenexposuretoradiationexceedingmaximumpermissibleforskin(MPE)PPE will be required for the following procedures:AlignmentOpenbeamexperimentsMaintenanceorservicinglasersystemsEmployers are obliged to provide employees with PPEProtective Eyewear Purpose:toreducelevelofincid
25、entlaserradiationuponcornea,tobelowMPE(MaximumPermissibleExposure)Filter:SufficientOpticalDensity(OD)toattenuateincidentradiationtoMPELegalrequirementtocomplywithBritishStandards:BS EN 207:Filters&equipmentusedforpersonaleyeprotectionagainstlaserradiationBS EN 208:Personaleye-protectorsusedforadjust
26、mentworkonlasersandlasersystemsEyeprotectionfiltersandequipmentmustbemarkedwith:1.Wavelength(orwavelengthrange)innmagainstwhichprotectionisafforded2.ScaleNumberatwhichwavelengths(oratleastOpticalDensity)3.Themanufacturersidentificationmark4.AppropriateCEmarkEyeprotectionnotusedwhenrequiredBadlyalign
27、edopticsAlteringbeampath(e.g.,addingopticalcomponentswithoutregardtobeampathInsertingreflectiveobjectsintobeampathBypassinginterlock(particularlyduringservicingandalignment)InappropriatelyturningonpowersupplyorfiringoflaserExposureofunprotectedthirdpartypersonnelEquipmentbreakdownCoversnotreplacedaf
28、terservice/alignmentLackofoperatortrainingNotanticipatingassociatedhazardsWorthNoting:MajorityofaccidentsarecausedbyassociatedhazardsCommon Causes of Incidents or AccidentsGeneral Safety Practices Whilst WorkingWearappropriateprotectiveeyewearwhenrequiredUseminimumpower/energyrequiredforprojectReduc
29、elaseroutputwithshutters/attenuators,ifpossibleTerminatelaserbeamwithbeamstopUsediffusereflectivescreens,remoteviewingsystems,lowpowerHeNelaseretc,duringalignments,ifpossibleRemoveunnecessaryobjectsfromvicinityoflaserKeepbeampathawayfromeyelevelDontputyourbodyparts(particularlyyoureyes)inthebeam!Con
30、trol all Hazards not just laser related Laserradiationhazards:Completecontainmentnotalwayspossibleforsomeapplicationse.g.alignment,servicingEnclosingasmuchbeampathasposs,interlocks,shuttersMechanicalorelectricalhazards:EngineeredoutofprocessEnclosedbyguardingorshields-interlockedEnvironmentalhazards
31、:VentilationorextractionsystemsHeating,lightingChemicalhazards:Ventilation,extraction,monitoring,substitutionofmaterialUseofPPEgloves,safetyeyewearVIDEO CLIP 3 Non-Beam HazardsHazard Evaluation and Risk AssessmentMajorityofaccidentsinworkplacearecausedby:InadequatetrainingFatigueErrorFailuretoplanan
32、dcarryoutworksafelyMH&SaWRegs1999andAORRegs2010EmployershaveadutytocarryoutfullriskassessmentsLaserusersmustuseequipmentinaccordancewithsafetytrainingorproceduresHazard:PotentialtocauseharmRiskfactor:P Productroductoflikelihood of hazard occurringandoutcome or harm that arises as a resultRisk Assess
33、ment Carriedoutbycompetentperson(LSOorlasersupervisorortrainedperson)IdentifysignificantrisksIdentify&prioritizemeasuresthatneedtobetaken 5steps:1.Lookforhazards2.Decidewhomightbeharmedandhow3.Evaluate,control,orreducetherisksi.e.decidewhetherexistingprecautionsareadequateoridentifyhowtocontrolorred
34、ucehazards4.Recordfindings5.Reviewassessmentfromtimetotimeandrevise RiskAssessment:1.Associatedlaserrisks:HeNe(Class3R)externalopticsalignmentS=staff,C=contractor,V=visitor,P=public,O=otherAssessmentnumber:Assessmentdate:18/03.02Assessedby:DavidJonesReviewdate:NextL.S.L.ResearchGroup:N/ALocation:J.A
35、.3.24STEP1STEP2STEP3List significant hazardsList groups of people at riskList existing controlsAre controls OK?Risk of hazard?Actions required ElectrocutionSHighvoltageterminalsproperlyshielded.Personsattemptinganyrepairmustbecompetent.YesLowNoneFloodingSAllwaterfittingstobeofsufficientstandard.Noel
36、ectricalpowersocketstobeonfloor.YesLowNoneSpillages / ingestion of contaminants.S,ONoeatingordrinkingintheLectureTheatreYesLowNoneHandling of liquid nitrogenNoLiquidNitrogenRequiredN/AN/AN/AInadequate lightingS,OPromptreportingandreplacementoffailedlighting.YesLowNoneTrip hazardsS,OAlltrailingcables
37、tobesecurelyanchoredatasafelevel(groundoraboveheadheight)andcoveredbycablestripswherecrossingpathwaysYesLowNoneFireS,OKnowledgeoffireexitsandassemblypointsYesLowNoneHandling of heavy or awkward objectsSPropermanualhandlingpracticetobeadheredto.Useofsuitableliftingequipmentandappropriatenumbersofpers
38、onnel.YesLowNoneAssessmentnumber:Assessmentdate:18/03/02Assessedby:DavidJonesReviewdate:N.L.S.L.ResearchGroup:N/ALocation:J.A.3.24STEP1STEP2STEP3List significant hazardsList groups of people at riskList existing controlsIs the control OK?Risk of hazard?Actions requiredPersonal injury due to lack of
39、care / improper useS,OTrainingofalllaserusers.Propagationofbestpracticeforlaseruse.Procedureforauthorisingcapableusers.YesLowInProgressUncontrolled accessS,C,V,P,OShieldlaserbeamfrompathtodoorswitchofflaserifexternalpersonsenterroomYesLowNoneEye damageS,O1.Caredonotlookalonglaserpath.2.Appropriateey
40、eprotectiontobeworn.3.Considerationoftheimplicationsofeachaligningstepbeforecommencement.4.Reflectionstobeminimisedandcontainedwithnohighlyreflectingobjectsinpathofbeam.1.Yes2.No3.Yes4.YesMediumObtainappropriateeyeprotectionglassesORLimitlaseroutputpowertobelow1mWduringalignmentAccidental diversion
41、of laser beamS,O1.Laserssecurelyfixedtoopticaltable2.Beamsteeringelementsheldsecurelyinposition.3.Nobeamcoveronperiscope.1.Yes2.Yes3.NoMediumFitsuitablecoveronperiscopeRiskAssessment:2.Specificlaserrisks:HeNe(Class3R)externalopticsalignmentS=staff,C=contractor,V=visitor,P=public,O=otherLocalRulesXDr
42、awn up by, or in consultation with, the Laser Protection AdviserXTo be read by all staff concernedXSign and date to say they have read and understood them and agree to follow themThepotentialhazardsControlledandsafeaccessAuthorisedusersresponsibilitiesMethodsofsafeworkingSafetychecksNormaloperatingp
43、roceduresPersonalprotectiveequipmentPreventionofusebyunauthorisedpersonsAdverseincidentproceduresListofauthorisedoperatorsOtherprotectionXWindowsanddoorsXFireextinguisherXWarningsignsandlightsXInterlocksXReflectivesurfacesLASER CONTROLLED AREAInvisible Laser BeamDO NOT ENTERSpecularanddiffusereflect
44、ionsEyeprotection:safetyglassesXMarkedforusewithcorrectlaser/IPLXMarkedwithODorScaleLandwavelength(s)XAllpersonsinthecontrolledareamustuseatalltimesunlessagreedbyLPAXCEmarking+compliantwithBSEN207XMustusecorrectonesXIfmorethanonetypeisneeded,keepglassesinseparatemarkedboxesXDesignedtoprotectfrombrie
45、faccidentalexposuresXDoNOTassumetheywillprotectfromdeliberate,prolongeddirectexposuresVIDEO CLIP 4 EyewearOtherhazardsXFireorexplosionXCryogensXBiologicaldyeXPlumeXSlips&tripsXManualhandlingXElectricalAccidentprocedureXSwitchofflaser.XImmediatefirstaid.XEyeexaminationifnecessary.XInformlocalLaserSaf
46、etyOfficer.XInformLaserProtectionAdviser.XIncidentreportform.XAccidentbook.XReporttoHSE,etc.Practical Laser Safety!?Practical Laser Safety - No!Dont drink or eatIn laser labEspecially; avoid alcohol!Avoid baggy jumpers and scarves(correct temp. in lab is essential)Remove watches and jewellery(includ
47、ing wedding rings)Tie long hair backPractical Laser Safety? - Yes!Hair restrained out of wayNo watch or jewelleryClear arms and clothing unlikely to snag optics or cross beam pathsAppropriate safety gogglePractical Laser Safety?!Practical Laser Safety Definitely No!Tools on tableNo laser screensFood
48、 and drink in labPeriscope not enclosedJewelleryHair unrestrainedCable hanging downLoose clothing in beampath Eyes at beam height - no safety gogglesUnsecured opticpost Loose coversArea poorly litPractical Laser Safety - Yes!Eyes well above beam height and safety goggles availableClear arms Laser sc
49、reensNo jewellery or watchProperly secured opticsUncluttered optical set-up and no tools on tableGeneral area well lit(1) EnsureEnsure all optics (lens, mirrors, etc) are securely fastened in the correct optical mount(2) EnsureEnsure all optical mounts (posts etc) are securely fastened to the optica
50、l table - not loose(3)(3)AlwaysAlways keep laser beams parallel to table surface and preferably at one common height(4) AlwaysAlways place beam stops as close as is practical to optics in set-up(5) NeverNever leave components or tools in optical set up5 safety bench rules Laser beam parallel to tabl
51、eBeam stopNote:Allcomponentsfastenedsecurelytotable-includingthelaser!NeverNever leave objects on optical tableNote:Beamcontainmentwallsaroundopticaltable(safetybelt!)Main laserHeNeDicroic or flip mirrorHeNe alignment laser - use this laser for initial alignment of opticsBeam containment wallsVariab
52、le or removable neutral density filterBeam alignment strategiesVisible main laser:(1) Use neutral density filter to reduce laser power to below 1 mW(2) Use low power ancillary laser ( 1 mW) for initial alignment of opticsInfrared laser or UV laser: ALWAYSALWAYS use low power ancillary laser ( 1 mW)
53、for initial alignment All lasers:All lasers:ALWAYSALWAYS - start at lowest power setting and first check for stray beams Changing beam height (1) NEVERNEVER incline laser beams always use periscopes (2) NEVER NEVER work with laser beams above the table beam stops Always enclose periscopeChanging bea
54、m height Use periscope to change beam height - NEVERNEVER incline laser beams Periscopes - initial alignment strategy (No laser required)(1) Make a height rule(2) Mark the in and out beam height on the rule(3) Position centre of mirrors at correct height (1) Position eye in line with rule and lower
55、mirror(2) Adjust bottom mirror until image of top mirror is centred on bottom mirror(1) Position eye in line with lower mirror(2) Adjust top mirror until image of mark on rule is centred on bottom mirrorSIMPLE - and much easer and safer that using a laserMUST HAVEMUST HAVE - no laser lab should be w
56、ithout at least one(1) EnsureEnsure all optics (lens, mirrors, etc) are securely fastened all optics (lens, mirrors, etc) are securely fastened in the correct optical mount in the correct optical mount(2) EnsureEnsure all optical mounts (posts etc) are securely fastened all optical mounts (posts etc
57、) are securely fastened to the optical table - not loose to the optical table - not loose(3)(3)AlwaysAlways keep laser beams parallel to table surface and preferably keep laser beams parallel to table surface and preferably at one common height at one common height(4) AlwaysAlways place beam stops a
58、s close as is practical to optics in set-upplace beam stops as close as is practical to optics in set-up(5) NeverNever leave components or tools in optical set upleave components or tools in optical set up The End Thank GodALWAYSALWAYS - start at lowest power setting and first check for stray beams start at lowest power setting and first check for stray beams 5 safety bench rules and
