Laser Safety Presentation David Baer – Former Laser Safety Officer Centre for Lasers & Applications Macquarie University - April 2004

Plan your experiment Source correct optics and mounting hardware Map out beam paths Do the Laser Safety Calculations The First Step in Laser Safety

The Old Classification System Approx. Power Limits for CW Visible Wavelengths Only Class 4 Unsafe for eyes Unsafe for skin 0.5 W Class 3B Unsafe for eyes Generally safe for skin 5 mW Class 3A Safe with (0.25 s.) aversion response no viewing aids 1 mW Class 2 Visible wavelengths only Safe with (0.25 s.) aversion response including viewing aids 220μW to 0.4μW Class 1 No precautions required

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

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.

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

Eye Effects Video Please follow the link on the Laser Safety web site to watch a video on laser radiation effects on the eye (46 MB, 5 min). From Laser Safety Video from Uni. of Southampton.

Laser Effects on Eyes and Skin

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

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

Laser 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

Laser Safety Video Please follow the link on the Laser Safety web page to watch a Laser Safety Video presentation from the Laser Institute of America (230MB, ~30 min). Visit the LIA websites – valuable information on lasers and safety is available here.

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).

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.

Optical – Research Lasers Research Lasers present additional dangers Multiple wavelengths – complicates selection of laser eyewear No Aperture stickers – be aware of beam paths

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)

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

Optical – Laser Labs No line of sight between optical tables and hallways. (use internal partitions and optical barriers on tables) STAGED

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).

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

Other Lab Hazards - Chemical Laser dyes – most dyes are carcinogenic Insulation Materials – Dusts, Fibres (Wear Masks) Optical Fibers – Eye hazards Solvents – flammability

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.

Other Lab Hazards - Gases Vacuum system – implosion issues with glass vessels. Safety glasses must be worn. Compressed gases – toxicity, flammability and asphyxiation hazards.

Other Lab Hazards - Cryogenic Liquid nitrogen – burns and asphyxiation hazards. Liquid N 2 can condense O 2 from the atmosphere and may cause an explosion. Ensure you have been trained in the correct way to handle liquid N 2. Do not accompany full Liquid N 2 Dewars in Lifts.

Other Lab Hazards - Combinations High Volts and Solvents/ Oils – Fire risk. High Voltages and Water – Electric shock. High Voltage 40 kV Water Cooling Insulation Materials Oil Cooling (Hot Oil) Laser Beam 200W Vacuum System High Temp 800C Ionising Radiation from Thyratron Toxic Gases UV from Discharge

Plan your experiment Source correct optics and mounting hardware Map out beam paths Do the Laser Safety Calculations The First Step in Laser Safety

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