This presentation covers basic laser safety. It discusses laser bioeffects such as damage to the eyes and skin. It describes laser hazards including reflective objects and accidental beam exposure. Laser classes are defined from Class 1 being safe to Class 4 being high power and a severe eye and skin hazard. Facility requirements include exposure limits, hazard zone markings, interlocks and protective equipment. A laser safety program requires engineering and administrative controls, training, permits and oversight by a Laser Safety Officer.

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Basic Laser SafetyBasic Laser Safety
Boston UniversityBoston University
Office of Medical PhysicsOffice of Medical Physics
and Radiation Safetyand Radiation Safety

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AgendaAgenda
1. Introduction
2. Bioeffects
3. Hazards
4. Hazard Classes
5. Facility Requirements
6. Program Requirements
7. Laser Permit Application
8. Laser Safety Exercise

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IntroductionIntroduction

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DefinitionDefinition
■ What is a Laser?
–Light Amplification by Stimulated Emission of
Radiation
– The energy generated by a laser is in or near the
optical portion of the electromagnetic spectrum

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The optical spectrum.
Laser light is nonionizing and ranges from the:
•ultra-violet (100 - 400nm)
•visible (400 - 700nm), and
•infrared (700nm - 1mm).
ElectroElectro--Magnetic SpectrumMagnetic Spectrum

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■ Laser light is:
– Monochromatic
– Directional
– Coherent
■ Lasers pose more hazard than ordinary light
because they focus energy onto a small area
Laser LightLaser Light

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BioeffectsBioeffects

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BioeffectsBioeffects
■ Primary sites of damage
– eyes
– skin
■ Laser damage can be:
– Thermal
– Acoustic
– Photochemical

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Human
Eye
For wavelengths that focus on the retina (400-
1400nm) the optical gain of the eye is about 100,000
times. If the irradiance entering the eye is 1mw/cm2,
then the irradiance at the retina will be 100W/cm2
Optical GainOptical Gain

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Mid-infrared and
Far Infrared
(IR-B and IR-C)
1400nm-1mm
and Middle
Ultraviolet
180nm - 315nm
Bioeffects of IR-B, IR-C and Mid UV

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Bioeffects of Near UV
Near Ultraviolet
(UV-A)
315-390nm

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Bioeffects of Visible and IR-A
Visible and
Near-infrared
(IR-A)
400-1400nm

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First Law of PhotobiologyFirst Law of Photobiology
Structure must absorb light to have an effect on it

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HazardsHazards

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■ Common Causes of Accidents
– Reflective objects in beam path (clutter)
– Grounding
– Movement of beam path
– Accidental energization or firing of laser
– Bypass of Interlocks
At CRC Call 3-SAFE
At BUMC Call 4-4444
AccidentsAccidents

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Types of IncidentsTypes of Incidents
Eye
62%
Death
3%Electric
1%
Embolism
1%
Skin
33%
Injury, death and incident data from Clark et al.“Trends in Laser Injury
Reporting” Joint International Laser Conference, 21-23 SEP03

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Common Causes of Death based onCommon Causes of Death based on
>1000 reports>1000 reports
■ 5 electrocution—all non-hospital events
■ 5 burns
■ 5 air or gas embolism—1 due to improper use
■ 3 airway tube fires
■ 2 bleeding
■ 2 improper use
■ 4 no information

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■ August 16, 1994 laser accident: A researcher working on the alignment
of the compressor for a femtosecond Ti:Sapphire laser system was struck
in the eye by a portion of the spectrally dispersed laser beam. The
resulting split-second exposure to a 1-kHz train of broadband 20-ps
pulses of at most 50 micro Joule centered at 800 nm, caused irreversible,
permanent retinal damage in the eye. The person in question lost vision
over a thin strip right in the middle of the central vision. While the brain
may adapt to correct for this loss of vision, the injury itself cannot
be remedied.
Ultrashort AccidentUltrashort Accident

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NonNon--Beam HazardsBeam Hazards
■ Electrical / High Voltage
– Most common
– Power supplies, capacitor banks
■ Chemical
– Dye lasers
– Compressed Gases
■ Laser Generated Air Contaminants
(LGAC)

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NonNon--Beam HazardsBeam Hazards
■ Optical
– UV from laser welding
– UV from discharge tubes and pumping
■ Fire/Explosion
– Ignition of gases and/or vapors
– Electrical Wiring and Capacitor banks
■ Noise
■ Safe during normal use

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Laser Hazard ClassesLaser Hazard Classes
Lasers are classified according to the level of laser
radiation that is accessible during normal operation.

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Class 1Class 1
CLASS I Laser Product
Nd:YAG Laser Marker
• Safe during normal use
• Incapable of causing injury
• Low power or enclosed beam
• Label not required
• May be higher class during maintenance or service
Label not required

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Class 2Class 2
CLASS II LASER PRODUCT
Laser Radiation
Do Not Stare Into Beam
Helium Neon Laser
1 milliwatt max/cw
Laser Scanners
• Staring into beam is eye hazard
• Eye protected by aversion response
• Visible lasers only
• CW maximum power 1 mW

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Class 3RClass 3R (Formerly 3a)
Small Beam
Expanded Beam
CLASS IIIa Laser Product
LASER RADIATION-
AVOID DIRECT EYE EXPOSURE
ND:YAG 532nm
5 milliwatts max/CW
Laser Pointers
CLASS IIIa LASER PRODUCT
Laser Radiation-
Do Not Stare Into Beam or View
Directly With Optical Instruments
Helium Neon Laser
5 milliwatt max/cw
•Aversion response may not provide adequate eye protection
•CDRH includes visible lasers only
•ANSI includes invisible lasers
•CW maximum power (visible) 5 mW

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Class 3BClass 3B
CLASS IIIb Laser Product
LASER RADIATION-
AVOID DIRECT EXPOSURE TO BEAM
2ω ND:YAG Wavelength: 532 nm
Output Power 80 mW
Courtesy of Sam’s Laser FAQ, www.repairfaq.org/sam/lasersam.htm, © 1994-2004
DPSS Laser with cover removed
•Direct exposure to beam is eye hazard
•Visible or invisible
•CW maximum power 500 mW

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Class 4Class 4
CLASS IV Laser Product
VISIBLE LASER RADIATION-
AVOID EYE OR SKIN EXPOSURE TO
DIRECT OR SCATTERED RADIATION
2ω Nd:YAG
Wavelength: 532 nm
Output Power 20 W
Photo: Keith Hunt - www.keithhunt.co.uk
Copyright: University of Sussex, Brighton (UK)
• Exposure to direct beam and scattered light is eye and
skin hazard
• Visible or invisible
• CW power >0.5 W
• Fire hazard

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M is for magnification.
A class 1M laser is class 1 unless magnifying optics are used.
A class 2M laser is class 2 unless magnifying optics are used.
M classes usually apply to expanded or diverging beams.
Class 1M & 2M
LASER
Condition 2
Diverging Beam
LASER
Condition 1
Expanded Beam

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Class 1Class 1 Incapable of causing injury during normal operation
Class 1MClass 1M Incapable of causing injury during normal operation
unless collecting optics are used
Class 2Class 2 Visible lasers incapable of causing injury in 0.25 s.
Class 2MClass 2M Visible lasers incapable of causing injury in 0.25 s
unless collecting optics are used
Class 3RClass 3R Marginally unsafe for intrabeam viewing; up to 5 times the
class 2 limit for visible lasers or 5 times the class 1 limit
for invisible lasers
Class 3BClass 3B Eye hazard for intrabeam viewing, usually not an eye
hazard for diffuse viewing
Class 4Class 4 Eye and skin hazard for both direct and scattered exposure
Laser Classification SummaryLaser Classification Summary

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Facility RequirementsFacility Requirements

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Exposure LimitsExposure Limits
■ MPE (Maximum Permissible Exposure)
– The highest laser energy exposure for eye or
skin for a given laser
■ NHZ (Nominal Hazard Zone)
– Area within which the MPE can be met or
exceeded

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Typical LaboratoryTypical Laboratory

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Laser Facility SpecificationLaser Facility Specification

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IlluminatedIlluminated ‘‘Laser In UseLaser In Use’’ SignSign

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EPO and Laser Power SwitchEPO and Laser Power Switch

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Braided Ground WireBraided Ground Wire

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TwistTwist--lock Receptacleslock Receptacles

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TwistTwist--lock Plugslock Plugs

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Laser CurtainsLaser Curtains

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Program RequirementsProgram Requirements

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■ ANSI Z136.1 specifies that any facility using Class 3b
or Class 4 lasers or laser systems should designate a
Laser Safety Officer to oversee safety for all
operational, maintenance, and servicing situations.
■ This person should have the authority and
responsibility to monitor and enforce the control of
laser hazards. This person is also responsible for the
evaluation of laser hazards and the establishment of
appropriate control measures.
Laser Safety Officer / LSOLaser Safety Officer / LSO

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■ Beam Housings
■ Shutters
■ Attenuators
■ Remote viewing devices
■ Interlocks/Twist-lock receptacles
■ Emergency Disconnects
■ Laser Curtains: Wilson LP 200
Engineering ControlsEngineering Controls

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■ Warning Signs
■ Labels
■ SOPs
■ Training
■ Security
Administrative ControlsAdministrative Controls

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TrainingTraining
■ Permit Holder
■ Authorized User
■ Coursework Experiments / Demonstrations
■ Initial
■ Annual Refresher

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■ Eyewear
– (appropriate for system – not necessarily
highest OD)
– Proper wavelength
– Sufficient number for users & visitors
– Centrally stored
■ Gloves
■ Viewing Devices
Personal Protective EquipmentPersonal Protective Equipment

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■ Laser Safety Committee/LSO
■ Laser Permits
■ Equipment Registration
■ Personnel Registration and Training
■ Eye Exams
■ SOPs and Signage
■ Emergency Procedures
■ Inspections and Monitoring
Elements of BU Laser Safety ProgramElements of BU Laser Safety Program

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■ Train users
■ Write SOPs
■ Select / provide PPE
■ Post emergency numbers and
procedures
■ Allow only authorized users to enter
hazard areas
■ Address non-beam hazards
Laser Permit HolderLaser Permit Holder’’s Roles Role

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Laser AlternateLaser Alternate’’s Roles Role
■ To fulfill all of the Permit Holder’s
responsibilities during his or her absence

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Laser LiaisonLaser Liaison’’s Roles Role
■ To serve as point of communication with LSO
■ To update all documentation and inform LSO
of additions / deletions / transfers
■ To coordinate training / eye exams /
inspections

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■ Eye Exam and Training
■ Follow SOP
■ Wear appropriate eyewear
■ Use minimum power required/reduce
output with attenuators
■ Keep beam path away from eye level
■ Remove unnecessary objects from table
Laser UserLaser User’’s Roles Role

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Communication with LSOCommunication with LSO
■ Equipment inventory updates 2 X per year
■ Personnel updates 3 X per year
■ Prior to acquiring a new laser
■ Prior to laser transfer / disposal
■ Immediately upon laser exposure incident or
near miss

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Equipment LabelsEquipment Labels

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Laser Permit Application

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Complete the Application Form
Submit the necessary attachments
1. Laser Equipment Inventory (3b /4)
2. Laser Personnel List
3. Laser User Authorization Form for each
Laser User
4. Laser SOP for each laser/laser system

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Laser Permit ApplicationLaser Permit Application

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Laser InventoryLaser Inventory

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Laser Personnel RosterLaser Personnel Roster

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Laser User AuthorizationLaser User Authorization

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Laser Standard Operating ProcedureLaser Standard Operating Procedure

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Laser Safety ExerciseLaser Safety Exercise

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Can you identify safe and/orCan you identify safe and/or
unsafe conditions?unsafe conditions?

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For Additional InformationFor Additional Information
■ Office of Medical Physics and Radiation Safety
– Laser Safety Officer: Ron Slade, 638-8828
– MC Main Office (Business Hours): 638-7052
– MC Emergency (24 Hours): 414-4444
– MC Fax: 638-7509
– CRC Main Office: 353-4094
– CRC Emergency (24 Hours): 353-7233 (SAFE)
– CRC Fax: 353-5646
– Web site: www.bu.edu/research/compliance/oehs/mprs
■ MA DPH Radiation Control Program
– 105 CMR 121.000 Regulations for the Control of Lasers
– Web site: www.state.ma.us/dph/rcp.radia.htm
■ ANSI Z-136 Series (esp. Z136.1 and Z136.5)