Laser Safety in the Lab

145 Pages·2013·6.262 MB·145\145

by  Barat, Kenneth

Laser
Safety
IN THE LAB
Ken Barat
Bellingham, Washington USA
LibraryofCongressCataloging-in-PublicationData
Barat,Kenneth.
Lasersafetyinthelab/KenBarat.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-8194-8819-0(alk.paper)
1. Lasers–Safety measures. 2. Laboratories–Safety measures. I.
Title.
TA1677.B3592013
621.36'60289–dc23
2011042692
Publishedby
SPIE
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Copyright cc 2013 Society of Photo-Optical Instrumentation
Engineers(SPIE)
All rights reserved. No part of this publication may be repro-
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permissionofthepublisher.
The content of this book (cid:85)(cid:72)(cid:192)(cid:72)(cid:70)(cid:87)s the work and thoughts of the
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accurate information herein, but the publisher is not responsible
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PrintedintheUnitedStatesofAmerica.
Second Printing
Preface
In 1960 T. Maiman demonstrated the first laser (ruby rod). I am
uncertainifheknewwhatanimpactitwouldhaveonsocietyand
theresearchcommunity.Atechnologyoncecommonlysaidtobe
looking for an application has now found a place in all sectors of
modernsociety.Inparticular,thelaserhasmadeadramaticimpact
onscientificresearch.
Within a few years of the development of that first laser, the
firstreportedeyeinjurybylaseroccurred.Evenbeforethen,itwas
clear to many that this new technology presented unique hazards,
andproductanduserguidancewasneeded.
In1973thefirstAmericanNationalStandardInstituteStandard
for the Safe Use of Lasers was published (ANSI Z136.1). From
thatyearforward,attemptstodeveloplasersafetyproceduresand
deviceshavebeeninprogress.
In addition to laying a foundation for laser safety, the goal of
thistextistogivethelaseruserausefulreferencesourceforlaser
safetysolutionsintheresearchanddevelopmentenvironment.
Special thanks to Dr. Robert Thomas, who kindly contributed
Chapter 4: Biological Effects and Appendix B: Laser Calculation
Hints. Robert is a physicist with the U.S. Army Research Lab., a
well-knowninstructorfortheHealthPhysicsSocietyProfessional
Enrichment Program courses, the webmaster for Z136.org, and a
finegentleman.
I would be remiss if I did not thank the people at SPIE who
have given me this opportunity—John Cain, Jane Lindelof, and
TimLamkins.
Sincere thanks to all I have encountered in my laser safety
career—Ifeeleachhasenrichedme.
xiii
xiv Preface
There is no more-challenging setting for laser use than a
research environment. In almost every other setting the laser
controls count on engineering controls, and human exposure is
kepttoaminimum,whereasinresearchtheuseroftenmanipulates
the optical layout and thereby places him or herself in peril. But
this does not mean that accidents and injury are unavoidable. On
thecontrary,laseraccidentscanbeavoidedbyfollowinganumber
ofsimpleapproaches.
A laser user may ask “Why do lasers receive such special
attention?” The chief reason is the optical gain of the eye for
wavelengths of 400–1400 nm. The average spot size of an image
focused onto a retina is 250 µm, while the retinal spot size for
a laser beam between 400–1400 nm focused by the lens onto
the retina is 20 µm; therefore, 1 mW is equal to 100 W/cm2
at the retina. A 1-W beam directed onto the retina is equal to
1,000,000 W/cm2, which is why even a 2–4% reflection from
an optical component could be over the threshold and cause eye
injury.Thisthresholdiscalledthemaximumpermissibleexposure
(MPE).
If you are not familiar with terms such as continuous wave
and pulsed laser, or with the basic properties of a laser, refer to
Appendix A before going on with this text. Another option is
to read SPIE’s Field Guide to Lasers, which gives an excellent
explanationoflaserproperties.
KenBarat
Berkeley,California
October2012
Contents
Preface....................................................................................xiii
Chapter1 HazardClassification.......................................... 1
1.1 Introduction........................................................................ 1
1.2 HazardClasses.................................................................. 2
Chapter2 RegulatoryLandscape....................................... 5
2.1 Introduction........................................................................ 5
2.2 ManufacturerRules......................................................... 6
2.2.1 FDA/CenterforDevicesandRadiolog-
icalHealth.......................................................... 6
2.2.2 InternationalElectrotechnicalCommis-
sion....................................................................... 7
2.3 UserRegulationsandGuidance.................................. 7
2.3.1 OccupationalandSafetyHealth
Administration.................................................. 7
2.3.2 FederalAviationAdministration................ 8
2.4 StateRegulations.............................................................. 9
2.4.1 ListofU.S.statesthathavelaserregu-
latoryprograms................................................. 10
2.5 UserStandards.................................................................. 11
2.6 ExportControls................................................................. 13
Chapter3 TheLaserSafetyOfficer..................................... 15
3.1 LaserSafetyOfficer/LaserSafetyAdvisor.............. 15
3.2 LSODuties......................................................................... 15
3.2.1 DelegationofLSOresponsibilities............ 17
vii
viii Contents
3.3 LaserSafetyCommittee................................................. 17
3.4 ManagementResponsibilityforLaserSafety........ 18
3.5 LaserSafetyProgram..................................................... 18
Chapter4 BiologicalEffects................................................ 21
ContributedbyRobertJ.Thomas
.
4.1 Introduction........................................................................ 21
4.2 ExposureType................................................................... 21
4.3 ExposurestotheEye....................................................... 22
4.3.1 Anatomyandopticsofthehumaneye..... 23
4.3.2 Aversionresponse............................................ 25
4.3.3 Dazzle/startleeffects....................................... 26
4.3.4 Wavelength-dependentbiologicaleffects 26
4.4 DamageMechanisms...................................................... 30
4.4.1 Photomechanical/Acousticdamage........... 30
4.4.2 Photoablation.................................................... 30
4.4.3 Thermaldamage............................................... 31
4.4.4 Photochemicaldamage.................................. 31
4.4.5 Effectoflow-powervisiblebeams............ 31
4.4.6 Extendedandpointsources.......................... 32
4.5 Laser-RadiationEffectsonSkin................................. 33
4.5.1 Epidermis............................................................ 34
4.5.2 Dermis................................................................. 34
4.5.3 Subcutaneoustissue........................................ 34
4.6 SkinInjury.......................................................................... 34
4.7 NominalHazardZone.................................................... 35
4.8 Specular Reflection Nominal Ocular Hazard
Distance............................................................................... 35
4.9 TheEffectofOpticalViewingInstruments............. 36
4.9.1 Normallight...................................................... 36
4.9.2 Laserlight........................................................... 36
FurtherReading............................................................................. 36
Chapter5 HazardEvaluationbyLSOorUser
Self-Assessment................................................. 39
5.1 HazardEvaluation............................................................ 39
5.2 DesigningaLaserLab/ExperimentalSetup............ 42
Contents ix
Chapter6 LaserProgramElementsandLaser
Controls............................................................... 43
6.1 LaserProgramElements................................................ 43
6.2 EngineeringControls...................................................... 43
6.3 AdministrativeControls................................................. 46
6.4 On-the-JobTraining(OJT)........................................... 49
6.5 StandardOperatingProcedures(SOP)...................... 51
6.6 BeamAlignmentProcedures........................................ 52
6.7 Class 3B and Class 4 Indoor Laser-Controlled
Area....................................................................................... 56
6.8 GuidanceforLaser-LabVisitors................................. 58
6.9 LaserLessons-LearnedProgram................................. 59
6.10 EventDescription............................................................. 60
6.10.1 Correctiveactions............................................ 60
6.11 LaserDisposal................................................................... 61
6.11.1 Laser-relatedwaste.......................................... 61
Chapter7 ProtectiveEyewear............................................. 63
7.1 Introduction........................................................................ 63
7.2 EyewearRequirements................................................... 64
7.3 Considerations in Choosing Laser-Protective
Eyewear............................................................................... 64
7.4 ComfortandFit................................................................. 65
7.5 OpticalDensity................................................................. 65
7.6 OpticalDensityTime-BasisCriteria......................... 66
7.7 VisibleLuminousTransmission(VLT).................... 67
7.8 IdentificationofEyewear.............................................. 69
7.9 CleaningandInspection................................................. 69
7.10 UltrafastLasers................................................................. 70
7.11 AlignmentEyewear......................................................... 70
7.11.1 Factorsinselectingalignmenteyewear.... 71
7.12 Eyewear Use with High-Power Lasers (High-
Power,MultikilowattLaserBeams).......................... 71
7.13 OtherFactors..................................................................... 72
x Contents
Chapter8 SpecialLasersandApplications....................... 75
8.1 FiberOpticSafety............................................................ 75
8.1.1 Diodes.................................................................. 78
8.2 Laser-ScanningConfocalMicroscope...................... 80
8.3 OutdoorLaserSafety...................................................... 81
8.3.1 Outdoorcontrolmeasures............................. 81
8.4 LaserPointersandHandheldLasers......................... 82
8.4.1 Userbeware:examples.................................. 83
8.4.2 Traditionaltypesoflaserpointers.............. 84
8.4.3 Newgenerationofhandheldlaser.............. 85
References....................................................................................... 86
Chapter9 NonbeamHazards............................................... 87
Chapter10 Life in the Laser Lab: Rules for Working in
theLaserLab....................................................... 91
10.1 PriortoStartingWork..................................................... 91
10.2 WorkLikeaLaserGuru................................................ 92
10.3 IndirectLaserBeamViewingTools........................... 93
10.3.1 LaminatedIR-viewingcards........................ 93
10.3.2 IRviewers.......................................................... 95
10.3.3 CCD/webcam.................................................... 96
10.3.4 Beamblocks...................................................... 96
10.3.5 Unsecuredbeamblocks................................. 97
10.3.6 Plasticlaserenclosures.................................. 98
10.3.7 Solidplasticbarriers....................................... 99
10.3.8 Metallaserenclosures.................................... 99
10.3.9 Lasercurtains.................................................... 101
10.4 OpticsonYourTable...................................................... 101
10.4.1 Checkformovement...................................... 102
10.4.2 Secureoptics..................................................... 102
10.4.3 Keepopticsclean............................................. 102
10.4.4 Transportingthebeama“longdistance”. 103
10.4.5 Dropping and picking up items from
thefloor............................................................... 103
10.4.6 Opticalmounts.................................................. 103
Contents xi
10.5 KnowYourOptics............................................................ 103
10.5.1 Cleaningoptics................................................. 105
Chapter11 LaserAccidents..................................................107
11.1 Introduction........................................................................ 107
11.2 SuspectedLaserInjury................................................... 108
11.3 AFewCaseHistories..................................................... 109
11.4 ThePerceivedIncident................................................... 110
Chapter12 BuildingaLaserSafetyCulture........................111
12.1 Introduction........................................................................ 111
12.2 ManagementTone............................................................ 111
12.3 InstitutionalTraining....................................................... 112
12.3.1 Lessons-learnedclass..................................... 113
12.3.2 On-the-jobtraining(mentoring)................. 113
12.3.3 Administrativecontrols................................. 114
12.3.4 Institutionalassurance.................................... 114
12.3.5 Useractions(stepback,housekeeping)... 115
Chapter13 Lay of the Lab: Hints for Designing Your
LaserLab.............................................................117
13.1 Checklist.............................................................................. 117
13.2 FurtherExamples............................................................. 119
AppendixALaserBasicsAbridged........................................129
A.1 LaserLightCharacteristics........................................... 129
A.2 CommonLaserComponents........................................ 130
A.3 ModesofOperation......................................................... 131
AppendixBLaserCalculationHints.......................................133
ContributedbyRobertJ.Thomas
.
B.1 UsefulApproximations.................................................. 133
B.2 ImportantConventions................................................... 134
B.2.1 Repetitivelypulsedlasers(RPLs).............. 135
xii Contents
B.2.2 Extended-sourceviewing.............................. 136
B.2.3 Diffusereflections........................................... 137
B.2.4 Nominalhazardzones.................................... 137
B.2.5 Protectiveeyewear........................................... 138
References(furtherreading)...................................................... 138
AppendixCLaserSafetyIllustrations....................................141
AppendixDGlossary...............................................................155
Index........................................................................................167