Laser Safety Training

1. Laser Safety

2. Introduction
• A Laser is a device that controls the way
energized atoms release photons.
• LASER is an acronym for “Light Amplification
by Stimulated Emission of Radiation”
• The light emitted by a laser is non-ionizing
electromagnetic radiation, that is, ultraviolet,
visible or infrared light.

3. Properties
Laser light has the following properties:
• Monochromatic (it contains one specific
wavelength of light)
• Coherent (organized, each photon
moves in step with the others)
• Directional (very tight, strong,
concentrated beams)
• Polarized

4. Beam Hazards
• Not only can direct beams
from a laser be hazardous
but reflections from laser
beams can also be
hazardous.
• Specular Reflection – can
occur when the surface
roughness is less than the
wavelength (mirror like)
• Diffuse Reflection – can occur
when the surface irregularities
are randomly oriented
(greater in size than
wavelength)

5. Integrated Safety
ManagementIntegrated Safety Management is a hazard analysis process that can be
used to reduce the risk of accident and injury.
Five Steps of Integrated Safety Management
1.Define scope of work
• What will the work/job/experiment involve?
2.Analyze hazards
• What are the hazards associated with
this job?
3.Develop/implement hazard controls
• What can be done to mitigate those
hazards?
4.Perform work within controls
5.Feedback and improvement
• Were all of the hazard mitigations followed?
• Was there anything that could have been changed to improve the quality and
safety of the work?

6. Integrated Safety
Management

7. Type of Lasers
• Solid State Lasers (lasing material distributed in a solid
matrix such as the Ruby or Yag laser)
• Gas Laser (have a primary output of visible red light such
as Helium-Neon lasers)
• Excimer Lasers (use reactive gases such as chlorine and
fluorine mixed with inert gases such as argon)
• Dye Lasers (use complex organic dyes such as Rhodamine
6G, in liquid solution or suspension as lasing medium)
• Semiconductor Laser (sometimes called diode lasers are
generally very small and use low power)

8. Laser Applications
• Commercial
• HeNe, Diode Lasers
• Scanners, CD’s, Laser Pointes, Printers
• Industrial
• CO2 Laser
• Welding, Marking, Cutting
• Nd:Yag
• Welding, Marking, Drilling
• Medical
• Argon, CO2, Nd:Yag and Dye
• Photocoagulation, Photoablation,
Photodisruption
• Military
• Fire control, Training, Marking Targets,
Ranging
• Research
• Single molecule detection, Spectroscopy,
Non-linear optics

9. Laser Hazard Classification
• Laser Hazard Classification system used to communicate
the potential hazard of a laser
• Developed by regulatory and standard organizations
• CDRH-FDA
• IEC
• ANSI
• ANSI Z136:
• All regulatory bodies use ANSI Z136.1 as their guidance document
for laser safety, even if they do not understand it
• OSHA in 2009 official recognized ANSI Z136.1 as its guidance on
laser safety

10. Laser Hazard Classes
• The purpose of
laser hazard
classification is to
alert one to the
potential hazard of
the laser system
• Remembering that
our laser systems
are evaluated and
controls are put in
place to mitigate
that potential
Class 1
Class 2
Class 3R
Class 3B
Class 4
Most Hazardous
Least Hazardous

11. Class 1 Laser
• Power output is too low to
cause eye or skin injury
• Example: laser printer
• Power = few microwatts
• High-powered expanded
beam
Class 1 Product:
Produces no exposure during
normal use, but contains a
higher class laser inside
SPECIAL NOTE
If you can make your set up
class 1 during operation, only
those that do actual
alignment need to take laser
safety training

12. Class 2 Laser
• Output less than 1 mill watt in visible range (400-700 nm)
• Counts on human’s aversion
response of 0.25 seconds to
prevent eye damage.
• Can be a hazard if the
aversion response is
over-ridden or slowed (stare
directly into the laser beam
for a long time).

13. Class 3R/3A
• 3A is an older classification
• Safe for momentary viewing
• Can be a hazard if viewed
using collecting optics (i.e.
microscopes).
• Power output is between 1
& 5 mW
• Light must be visible to be a
commercial product

14. Class 3B
• Can produce a moderate to high
hazard if viewed directly with the
eye.
• Intrabeam viewing hazard
• Specular reflection hazard
• Diffuse reflections are not harmful
• Light can be visible or invisible
• Continuous wave output between
5-500 mW
• Pulse laser limit - cannot produce
125mJ in less than 0.25 second

15. Class 4
• Pose greatest danger
• Power output higher than Class 3B
• Intrabeam viewing hazard
• Specular reflection hazard
• Possible diffuse reflection hazard
• Fire hazard (can ignite combustible
materials)
• Skin hazard (laser can burn the skin)

16. New classification Z136.1-2007 & IEC*: 1M/2M
1 M
• Invisible
• Safe to view in
absence of collecting
optics
• Likelihood of viewing
with collecting optics
needs to be
evaluated
2M
• Visible
• Safe to view in absence
of collecting optics
• Likelihood of viewing
with collecting optics
needs to be evaluated
• Many metrology
devices could be
classified as Class 2 M
*IEC – International Electrotechnical Commission

17. Laser Hazard
If the laser irradiance
entering the eye is 1
mW/cm2
, the
irradiance at the
retina (back of the
eye) will be 100
W/cm2
. This is for
wavelength between
400-1400 nm
It is the high optical
gain of the eye that
makes lasers such a
hazard.
From D.H. Sliney and M.L. Wolbarsht, Safety with Lasers and Other Optical Sources, New
York and London: Plenum Press, 1980.

18. Biological Hazards - Skin
• Ultraviolet (UV)
• UV can cause skin injuries comparable to sun burn.
• As with damage from the sun, there is an increased risk
for developing skin cancer from UV laser exposure.
• Thermal Injuries
• High powered (Class 4) lasers, especially from the
infrared (IR) and visible range of the spectrum, can burn
the skin and even set clothes on fire.
18

19. Skin
Penetration
To Fast To
React!

20. 800 nm trap
Just like an iceberg your mind
can trick you into making a
serious mistake.
• The eye perceives only
about 0.1 % of the light of
wavelengths between 750-
830 nm
• Meaning if one can see a
faint dot at these
wavelengths there is a
great deal of energy
present. Similar to iceberg
analogy

21. Laser Safety
• PROTECT YOUR EYES! Only use laser eye
protection specifically labeled for the type
of laser used
• Just because the eyewear is the right color does
not mean it will stop the laser
• Unlike many hazards, the laser beam can pose a
hazard at a considerable distance
• Unlike ionizing radiation, laser radiation is only
hazardous when it is on and when you have line-of-
sight to the beam
• Identify and be aware of specular and diffuse
reflections
• Consider unanticipated reflections

22. Laser Bioeffects and Hazards
Corneal Injury
• Mid-Infrared and Far-Infared (1400nm-
1mm) and Middle-Ultraviolet (180nm-
315nm)
• A minor corneal injury can repair itself in
about 48 hours
• Deep burns to the cornea produce a
permanent opacity and my require a
corneal transplant for repair

23. Laser Bioeffects and Hazards
Lens Injury
•Near-Ultraviolet (315nm-390nm)
•Can cause cataracts (clouding of the
lens)

24. Laser Bioeffects and Hazards
Retinal Injury
• Visible and Near Infrared
(400nm-1400nm)
• Can cause blind spots in
vision
• Can cause retinal
hemorrhage
•The optical gain of the eye is
approximately 100,000!
•A corneal irradiance of 1
W/cm2 from a laser may
produce a retinal irradiance of
100 kW/cm2!

25. Laser Bioeffects and Hazards
• The most serious eye injuries have been caused by
the Q-switched Nd:YAG
• Xe-CL eximer laser at 308nm has the greatest
potential for producing cataracts
• Lasers most likely to produce retinal injury are the
Ruby 649.3nm and the YAG 1064nm
• Most laser injuries occur during alignment (always
use the appropriate alignment goggles)

26. Photobiological Spectral
Domain (CIE Band)
Eye
Effects
Skin
Effects
Ultraviolet C
(200-280 nm)
Photokeratitis
Erythema (Sunburn)
Skin Cancer
Ultraviolet B
(280-315 nm)
Photokeratitis
Erythema (Sunburn)
Accelerated Skin Aging
Increased Pigmentation
Ultraviolet A
(315-400 nm)
Photochemical UV
Cataract
Pigment Darkening
Skin Burn
Visible
(400-780 nm)
Photochemical and Thermal
Retinal Injury
Color and Night
Vision Degradation
Skin Burn
Photosensitive Reactions
Infrared A
(780-1400 nm)
Retinal Burns
Cataract
Skin Burn
Infrared B
(1400-3000 nm)
Corneal Burn
Aqueous Flare
IR Cataract
Skin Burn
Infrared C
(3000-1 million nm)
Corneal Burn Skin Burn

27. Eye Protection
• All laser eyewear must be
marked with the Optical
Density (OD) as a function of
wavelength
• Laser eyewear is not for
direct viewing of the beam
• Keep eyewear clean and free
from scratches
• Inspect eyewear before use
• Store eyewear away from
contaminants
• Do not store goggles by
hanging from the strap

28. EYEWEAR LABELS
All eyewear must be labeled with wavelength and optical density.

29. Wavelength Range
What if your eyewear is labeled 532 nm and
your laser is 537 nm or 540 nm can you use it?
Seems close so why not?
•Protection for any wavelength not listed on the
eyewear is uncertain. The wavelength coverage
may drop like a stone outside the labeled range
•Other cases there maybe a gradual drop off
•Manufacturer curves are helpful but not the
complete answer.

30. Optical Density
The protective goal of laser eyewear is such that if
laser radiation strikes the lens portion of the
eyewear, the lens will completely block or reduce
any transmitted radiation to below the Maximum
Permissible Exposure (MPE) level.
This filtration or protection level is called optical
density (OD).

31. OD Selection
• For Ultra-Violet and Infrared Radiation the
OD selected should offer full protection.
• For visible wavelengths it is a common
mistake to select full protection OD. For
alignment purposes, users should select
less than full protection OD to allow some
visibility of the beam.

32. Eyewear Considerations
Many factors should go into the selection of
laser protective eyewear
• Multiple wavelengths in use
• Fit
• OD
• Visual light transmission
• Room illuminations
• All eyewear selections should be
reviewed by the Laser Safety Officer
(LSO)

33. Types of Exposure
Direct/intrabeam exposure:
Exposed directly to all or part of the laser beam which leads to
the saying, “do not look at laser with your remaining eye”.
Specular:
A reflection from a mirror-like surface. A laser beam can
retain all of its original power or just a percentage when
reflected in this manner.
Diffuse:
A reflection from a dull surface. Safest way to view a beam

34. Reflection type depends on wavelength &
surface
Specular
Reflection
Diffuse
Reflection
Reflection
NOTE:A flat black surface can be specular in the near infrared

35. Non Beam Hazards
Do not develop tunnel vision
• Laser Safety is not only eye
hazards
• Most laser user deaths are a
result of Non-Beam Hazards
Electrocution or Fire

36. Non-Beam Hazards list from ANSI
Z136.1“Non-beam Hazards” section provides guidance
on:
• Electrical hazards (Sec. 7.2.1)
• Collateral and plasma radiation (Sec. 7.2.2)
• Fire hazards (Sec. 7.2.3)
• Explosion hazards (Sec. 7.2.4)
• Mechanical hazards associated with robotics
(Sec. 7.2.5)
• Noise (Sec 7.2.6)
• Laser generated airborne contaminants (Sec.
7.3.1)
• Compressed gases (Sec. 7.3.2)
• Laser dyes and solvents (Sec. 7.3.3)
• Assist gases (Sec 7.3.4)
• Biological agents (Sec. 7.4)
• Human factors (Sec. 7.5)

37. Control Measures
•A number of Engineering and
Administrative controls exist to help
you work safely
•They will be outlined in the SOP for
your laser work
•Engineering controls are preferred
because they remove the human
error element

38. Control Measures
Engineering:
• Automatic illumination of signs when laser is powered on
• Interlocks and controlled access
Administrative and Procedural:
• Training
• PPE
• Laser Curtains
• Standard Operating Procedures
• Emergency shut off buttons in laser labs
• Posting of laser warning signs

39. Laser Accidents:
• It is estimated that 60-70% of all (known)
R&D laser laboratory accidents occur
during alignment.
• Common scenario: unanticipated
reflection from an
optic while
not wearing
protective eyewear

40. Laser Accidents:
• Not wearing appropriate protective eyewear
• Wearing inappropriate eyewear
• Wrong OD, e.g.,
• Wearing low-OD alignment eyewear with operational power levels
• Wearing high-OD operational eyewear with low-power
(alignment) power levels
• Wavelength compatibility problem, especially for multiple
wavelengths
• Turning to look at source of bright light detected by peripheral vision
• Elevating (vertical) beams – aim it at your face
• Not determining location of stray / errant beams
• Poor communication between co-workers
Hazardous acts that can result in laser accidents
include:

41. TRICKS OF THE TRADE: Safety
•POLARIZATION BEAMSPLITTER CUBES OR GLAN-
TAYLOR: Beware of reflected beams when rotating the
cube/prisms.
Major eye killers…
•ND FILTERS: Beware of reflected beams when you put
an ND filters into a beam path.

42. •REFLECTIVE PERISCOPES: Beware of misadjusted
periscope, especially the 90o
reflective polarization rotator
TRICKS OF THE TRADE: Safety
Major eye killers (cont’d.)…
•HARMONIC GENERATION CRYSTALS: Beware of
reflected beams when crystals are rotated to find phase
matching angle

43. •REFLECTIVE ALIGNMENT TOOLS: Beware to ALWAYS
consider reflected beam off hemostats and IR card during
alignments
•FLIPPER MOUNT: Beware to ALWAYS consider reflected
beam DURING flipping motion. NEVER flip while a laser
beam is present !!!
TRICKS OF THE TRADE: Safety
Major eye killers (cont’d.)…

44. Safe Work Practices
• Always wear the appropriate eyewear
• Know the standard operating and alignment procedures for
the laser you are working with
• Identify necessary equipment and procedures before
beginning
• View beams indirectly
• Remove jewelry and items from shirt pockets
• Pay attention to housekeeping: remove unnecessary items
• Make sure beam shutter is closed before starting
• Use class 1 laser products when ever possible
• Enclose as much of the beam as possible
• Don’t direct beam towards door and windows
• Don’t locate beam at eye level
• Terminate beams or reflections with fire resistant beam stops

45. Safe Work Practices
• Utilize surfaces that scatter radiation and minimize specular
reflection
• Locate controls so operator is not exposed to beam and non-
beam hazards
• Make sure warning/indicator lights can be seen through
protective filters
• View application remotely when possible
• During alignment, use minimum beam power or low-power,
coaxial beam for path simulation
• Before alignment, prepare beam delivery system & check
optics
• During alignment, use beam blocks behind optics to be
adjusted to stop stray beams
• View diffuse reflections only
• Entry doors should be closed and locked and appropriate
signs posted when laser is operational

46. Users
• It is important that you follow the procedures and
requirements to use Class 3B & Class 4 Lasers at
the FAMU.
• Complete on-line training course(s)
• Receive use specific on the job training (OJT) by
the laser owner or supervisor of laser use area
• Read and comply with SOP
• Where protective eyewear
• Ask questions, your safety is important to all

47. Safety Guidelines
• Everyone using lasers at Florida A&M University must receive
safety training
• Installation of new lasers must be reviewed by the
Environmental Health & Safety Dept. before operation
• Appropriate laser safety glasses must be obtained and all
engineering or administrative controls in place before
operating lasers at FAMU
• Maintenance and service of lasers must be performed by
qualified technicians for all classes of lasers
• Manufacturer’s installed protective housing on all classes of
lasers and laser systems shall be maintained and not be
removed when the laser is operational
• Never leave an operating laser unattended
• For class 3 and 4 lasers, standard operating procedures shall be
developed and stored in prominent locations

48. WORK
SAFELY!