Laser Safety

1

• Laser Safety
• Presentation

David Baer Former Laser Safety Officer Centre
for Lasers Applications Macquarie
University - April 2004
2
The First Step in Laser Safety

• Plan your experiment
• Source correct optics and mounting hardware
• Map out beam paths
• Do the Laser Safety Calculations

3
The Old Classification System
Approx. Power Limits for CW Visible Wavelengths Only Class 4 Unsafe for eyes Unsafe for skin
Approx. Power Limits for CW Visible Wavelengths Only 0.5 W Class 3B Unsafe for eyes Generally safe for skin
Approx. Power Limits for CW Visible Wavelengths Only 5 mW Class 3A Safe with (0.25 s.) aversion response no viewing aids
Approx. Power Limits for CW Visible Wavelengths Only 1 mW Class 2 Visible wavelengths only Safe with (0.25 s.) aversion response including viewing aids
Approx. Power Limits for CW Visible Wavelengths Only 220µW to 0.4µW Class 1 No precautions required
4
The New Classification System
Approx. Power Limits for CW Visible Wavelengths Only Class 4 Unsafe for eyes Unsafe for skin
Approx. Power Limits for CW Visible Wavelengths Only 500mW Class 3B Unsafe for eyes Generally safe for skin
Approx. Power Limits for CW Visible Wavelengths Only 5mW Class 3R Safe with (0.25 s.) aversion response no viewing aids
Approx. Power Limits for CW Visible Wavelengths Only 5mW Class 2M Visible wavelengths only Safe with no viewing aids
Approx. Power Limits for CW Visible Wavelengths Only 1mW Class 2 Visible wavelengths only Safe with (0.25 s.) aversion response including viewing aids
Approx. Power Limits for CW Visible Wavelengths Only 1mW Class 1M Safe with no viewing aids
Approx. Power Limits for CW Visible Wavelengths Only 39µW to 390µW (depending on ?) Class 1 No precautions required
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Why Lasers Are Hazardous

• 2 Main Factors.

• Collimation Effects More light can be
  introduced into the eyes compared to other light
  sources.
• 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.

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To Determine the Laser Hazard

• 6 main factors need to be taken Consideration.

• Wavelength
• CW or Pulsed Operation
• Power or Pulse Energy
• Repetition Rate (PRF)
• Beam Diameter Profile
• Beam Divergence

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Eye Effects Video Segment

• Laser radiation effects on the eye.
• From Laser Safety Video from Uni. of Southampton.

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Laser Safety Eye Effects Video
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Laser Effects on Eyes and Skin
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Lasers Safety Precautions

• Class 1 1M Lasers - No Precautions
• Class 2 2M Lasers - No Staring
• Class 3R Lasers - No Staring
• (also old Class 3A lasers) - No Magnifiers

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Lasers Safety Precautions

• Class 3B - Avoid Exposure
• Class 4 Lasers - Know the NOHD
• - Controlled Area
• - Use Beam Stops
• - Diffuse Reflections Hazardous
• - Use Eye Protection
• - Interlocks Required
• - Chemical / Electrical hazards

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Laser Safety _at_ the Faculty of Science

• Majority of lasers are High Power Class IV Lasers
• Research lasers may have many wavelengths
• Laser, Chemical and Electrical safety procedures
  must be followed
• No Laser maintenance after hours

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Laser Safety Video

• Laser Safety Video presentation from the Laser
  Institute of America.
• Visit the LIA websites valuable information on
  lasers and safety is available here.
• www.lasersafety.org
• www.laserinstitute.org

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Laser Safety Video
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General Laboratory Safety

• Clothing No watches rings. Long sleeve
  clothing encouraged. Wear enclosed footwear in
  labs.
• Tripping hazards cables, equipment on floors.
  Use cable trays whenever possible.
• Housekeeping When finished with equipment, put
  it away. If equipment is broken, get it fixed
  (see your supervisor).

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General Laser Lab Safety

• Never directly view a laser beam.
• Never remove covers from equipment without
  approval from supervisors laser, high voltages
  and other hazards are present.
• Although no deaths have been recorded from laser
  beam exposure, a number of people have been
  killed by Laser HV Excitation circuits.
• Familiarise yourselves with the Australian laser
  safety standard (present in most labs) and the
  MSDS folders regarding chemicals and materials
  you use. If relevant MSDSs are missing inform
  your Supervisor.

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Optical Research Lasers

• Research Lasers present additional dangers
• Multiple wavelengths complicates selection of
  laser eyewear

• No Aperture stickers be aware of beam paths

18
Optical Table Hardware

• Avoid the use of periscopes, keep laser beams in
  the one horizontal plane on optical tables. (A
  researcher at a university was permanently
  blinded aligning a periscope)
• Never use horizontal beam posts. (if a mirror is
  knocked, it can deflect a beam off the horizontal
  plane)

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Optical Laser Monitoring

• Use alignment jigs and attenuators during set up
• Consider using remote monitoring (cameras, laser
  beam analysers, fluorescent crystals and cards)

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Optical Laser Labs

• No line of sight between optical tables and
  hallways. (use internal partitions and optical
  barriers on tables)

STAGED
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Optical Laser Labs

• A labyrinth style entryway into labs, giving a
  safe area to put on safety equipment (PPE).
• A storage rack for laser safety eyewear (labeled
  with wavelengths etc).

22
Laser Generated Air Contaminants

• Machining polymers can release acidic and
  carcinogenic by-products
• Familiarise yourself with any potential
  by-products
• Consult MSDS, reference books and supervisors
• Use adequate extraction

23
Other Lab Hazards - Chemical

• Laser dyes most dyes are carcinogenic
• Insulation Materials Dusts, Fibres (Wear Masks)
• Optical Fibers Eye hazards
• Solvents flammability

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Other Lab Hazards - Electrical

• High voltages Always ensure covers are in
  place.
• 240 v No uninsulated connections permitted.
• Use removable insulated covers on experimental
  circuits. Dont leave live circuits unattended.
• Safety Concerns - Contact Greg Yates from METS.

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Other Lab Hazards - Gases

• Vacuum system implosion issues with glass
  vessels. Safety glasses must be worn.
• Compressed gases toxicity, flammability and
  asphyxiation hazards.

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Other Lab Hazards - Cryogenic

• Liquid nitrogen burns and asphyxiation hazards.
  
• 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.

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Other Lab Hazards - Combinations
Toxic Gases
Laser Beam 200W
Vacuum System
High Voltage 40 kV
High Temp 800C
Water Cooling
Insulation Materials
UV from Discharge
Oil Cooling (Hot Oil)
Ionising Radiation from Thyratron

• High Volts and Solvents/ Oils Fire risk.
• High Voltages and Water Electric shock.

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The First Step in Laser Safety

• Plan your experiment
• Source correct optics and mounting hardware
• Map out beam paths
• Do the Laser Safety Calculations

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Conclusion

• Always wear correct Laser Safety Glasses
• Consider all the implications of your project.
• Always think what your doing.
• Report any lab problems or concerns to your
  supervisor and/or Susan Law (E7B-351, x8126).

Updated Jan 2010