Working with
Lasers
Deakin University
Working with Lasers
Part 1: Background information
Part 2: Laser hazards to consider
Part 3: Laser classification
Part 4: Laser safety
Part 5: Lasers at Deakin
Part 1:
Background Information
• How lasers work
• Why they are hazardous
How Lasers work
•
•
•
•
Laser Material (gas, liquid, solid, semiconductor)
Pump/Excitation Mechanism (discharge, flashlamp, laser)
Feedback Mechanism (mirror)
Output coupler (semi-transparent mirror)
Why Lasers Are Hazardous
Laser light differs from light from other sources in several
ways:
– Monochromatic (single wavelength)
– Directional (Low Divergence)
– Coherent
Laser light can pose an extreme hazard
because a lot of energy is concentrated in
a small area
Why Lasers Are Hazardous
2 Main Factors
1. Collimation Effects :
Collimated light means the
photons emitted from the laser are in parallel not
scattered like conventional light sources. Therefore more
light can be introduced into the eyes compared to other
light sources.
Why Lasers Are Hazardous
2 Main Factors
2. Spot Size Effects : Radiation in the 400 – 1400nm
region is brought to a sharp focus on the retina. This can
increase the radiant exposure (irradiance) by approx
100,000 times.
Part 2:
Laser Hazards to Consider
1. Beam Hazards
• Damage to the eye
• Damage to the skin
2. Non-Beam Hazards
• Electrical safety
• Chemical safety
• Airborne contaminants
• Noise safety
Beam hazardsEffects on Eyes and Skin by wavelength
Non-beam Hazards:
Chemical

Laser dyes – most dyes are carcinogenic
 Insulation Materials – Dusts, Fibres (Wear Masks)
 Optical Fibers – Eye hazards
 Solvents – flammability
Non-beam Hazards:
Electrical
• High voltages – Always ensure covers are in place.
• 240 v – No uninsulated connections permitted.
• Don’t leave live circuits unattended.
Non-beam hazards:
Gases

Compressed gases – toxicity, flammability and
asphyxiation hazards.

Vacuum system – implosion issues with glass
vessels. Safety glasses must be worn.
Non-beam hazards:
Cryogenics
 Liquid nitrogen – cold burns
and asphyxiation hazard.

Liquid N2 can condense O2
from the atmosphere and
may cause an explosion.

Ensure you have been
trained in the correct way to
handle liquid N2.
 Do not accompany full
Liquid N2 Dewars in Lifts.
Non-beam hazards:
Laser Generated Air Contaminants
•
Laser cutters can generate
hazardous dust particles
•
Familiarise yourself with any
potential by-products
•
Consult MSDS, reference
books and supervisors
•
Use adequate extraction
Lab Hazards Combinations
Toxic Gases
Laser Beam
200W
Vacuum System
High Voltage
40 kV
High Temp 800C
UV from
Discharge
Ionising
Radiation
Water Cooling
Insulation
Materials
Oil Cooling
(Hot Oil)
Part 3:
Laser Classification
Factors affecting Laser
classification level
6 main factors to consider:
- Wavelength
- Continuous Wave or Pulsed Operation
- Power or Pulse Energy
- Repetition Rate (PRF)
- Beam Diameter & Profile
- Beam Divergence
Laser Classification System
Approx. Power Limits for CW
Visible Wavelengths Only
Class 4
Unsafe for eyes
Unsafe for skin
0.5W
Class 3B
Unsafe for eyes
Generally safe for skin
5mW
Class 3R
Safe with (0.25 s.) aversion
response no viewing aids
0.5W
Class 2M
Safe with no viewing aids
Visible wavelengths only
1mW
Class 2
Visible wavelengths only
0.5W
Class 1M
220μW to 0.4μW
Class 1
Safe with (0.25 s.) aversion
response including viewing aids
Safe with no viewing aids
No precautions
required
Old Laser Classification System
Approx. Power Limits for CW
Visible Wavelengths Only
Class 4
0.5 W
Class 3B
5 mW
Class 3A
1 mW
Class 2
Visible wavelengths only
Unsafe for eyes
Unsafe for skin
Unsafe for eyes
Generally safe for skin
Safe with (0.25 s.) aversion
response no viewing aids
Safe with (0.25 s.) aversion
response including viewing aids
220μW to 0.4μW
Class 1
No precautions
required
Laser Safety Precautions
by classification
Class 1 Lasers :
- Safe
Class 1M Lasers:
- No viewing aids
Class 2 Lasers :
- Safe with aversion response
(No staring)
Class 2M Lasers:
- Safe with aversion response
(No staring); No viewing aids
Class 3R Lasers :
(also old Class 3A lasers)
- No Staring, No viewing aids,
Unsafe outside visible range
Laser Safety Precautions
by classification, cont.
Class 3B Lasers :
- Unsafe for eyes, generally
safe for skin
Class 4 Lasers :
- Unsafe for eyes, unsafe for
skin
Part 4:
Laser safety
General Laser Lab Safety
 Never directly view a laser beam.
 Never point a laser pointer at a person.
 Never over-ride interlocks
 Never remove covers from equipment without
approval from supervisors – laser, high voltages
and other hazards are present.
General Laser Lab Safety, cont.
 Clothing: Long sleeve clothing should be worn to
protect skin. Wear enclosed footwear in labs.
 Jewelry: watches & rings which could reflect
beams should not be worn.
 Viewing Aids: Never use microscopes, telescopes,
magnifying glasses etc to view laser beams
Special Considerations for
Class 3B & 4 Lasers
• Avoid Exposure of eyes & skin
• Work in Controlled Areas
• Diffuse Reflections are Hazardous
• Use Beam Stops
• Use Eye Protection
• Post Warning signs
• Interlocks Required

Laser Lab design
A labyrinth style entryway into labs, giving a safe
area to put on safety equipment (PPE).
 A storage rack for laser safety eyewear (labelled
with wavelengths etc).

Laser operators should not be seated at beam
height to avoid possible exposure
Laser hazard controls
Hierarchy of controls




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Elimination
Substitution
Isolation
Engineering
Administration
PPE
Laser Controls
Engineering
•
•
•
•
•
Protective Housings
Remote Interlocks
Access Panels
Master Switches
Enclosed beam baths
Laser Controls
Administrative
•
•
•
•
•
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Laser Safety Officer
Safe Working Procedures (SWPs)
User registration
Record keeping
Correct Labelling of device and area
Medical surveillance (Eye tests)
Laser Warning
signs
Medical Surveillance
> Eye testing before and after the use of
Class 3B & Class 4 lasers is recommended
Visual acuity
Ishihara test
Amsler Grid
Laser Controls
PPE
The main form of protective equipment is
protective eyewear, but when using Class 4
lasers protective clothing and footwear must
also be worn
Eye protection
> Ensure the correct wavelengths are
covered (not all safety eyewear materials
are the same) otherwise the safety
goggles may be offering no protection for
the laser you are working with
A note about
Eye safe lasers
Lasers with emission wavelengths longer than 1400nm are often labelled
as ‘eye-safe’ because wavelengths greater than 1400nm are strongly
absorbed in the cornea & lens of the eye rather than the relatively more
sensitive retina.
High powered or pulsed lasers at these wavelengths will still burn the
cornea and cause severe eye damage. Corneal injuries are very painful.
A laser labelled eye-safe should be treated the same as any other laser –
with extreme caution. NEVER stare at a laser beam.
Part 5:
Lasers at Deakin
 Majority of lasers are Low Power, Class 1 &


2 Laser Pointers
Laser, Chemical and Electrical safety
procedures must be followed
No Laser use after hours or by untrained
personnel
Deakin laser procedures
 All lasers must be on the University laser register
 All work should be covered by a Project Safety


Plan which has been signed off by a lab manager
and the University Radiation Safety Officer
A Laser Hazard Identification checklist must be
completed for Laser classes 3 and above
Class 3B and Class 4 lasers should have a
written Safe Working Procedure on hand –
guidelines available
Laser pointers
Laser pointers are effective tools when used properly. The following
considerations should be observed when using them:
• Use only laser pointers with AS/NZS 2211 classification Class 1 or
Class 2.
• Do not use or purchase a laser pointer that has a stated emission level
of greater than 1mW
• Ensure Class 2 lasers are labelled correctly "Caution: Laser Radiation.
Do not stare into the beam. Class 2 Laser Product."
• Never look directly into the laser beam.
• Never point a laser beam at a person.
• Do not aim the laser at reflective surfaces.
• Do not allow children to use laser pointers.
Conclusion

Consider all the implications of your laser use,
including those around you.

Never stare at a laser beam

Always wear correct Laser Safety Glasses

Report any lab problems or concerns to your
supervisor and/or the University radiation
safety officer