The reduction in cost of low to medium-power industrial lasers has led to a significant increase in their use and ownership. As such, it is important that we ensure this is married with a sound understanding of the safety implications of lasers, and how we can ensure their safe use. In this blog, we take a look at some of the fundamental basics of laser safety.
What are the hazards?
The hazards of a laser system primarily depend on its power and wavelength, with eye damage being the most significant risk due to the eye's sensitivity to light. Here are key hazards based on laser type:
Eye Damage:
Fibre Lasers (wavelength around 1000 nm, in the infrared range): These are highly dangerous as their light passes through the cornea and lens to focus directly on the retina, which increases light intensity and can cause severe retinal damage, blind spots, or blindness. The invisible infrared light also prevents natural protective responses (like blinking), making accidental exposure especially hazardous.
CO₂ Lasers (wavelength around 10 μm, also in the infrared range): The cornea absorbs this laser type, leading to surface heating and risks of corneal burns. Long-term exposure can dry the eye, causing irritation similar to sunburn and premature aging of the eye’s surface.
Long-Term Effects:
Fibre Lasers: Prolonged exposure can lead to cataracts in the eye’s lens, resulting in cloudiness and potential blindness. Cataract surgery can restore vision by replacing the damaged lens.
CO₂ Lasers: Extended exposure can lead to chronic dryness, corneal distortion, and diminished clarity of vision.
The unique properties of lasers—such as the ability to focus into small, intense beams that diverge little over distance—enhance their danger, making high-intensity light harmful even at a distance from the source.
Where are the hazards?
Laser beams can travel long distances with minimal spreading, keeping their intensity high over great lengths. Laser safety standards provide guidelines for safe exposure levels.
For instance:
A 20 W fibre laser poses an eye hazard up to 3 km away, called the Nominal Ocular Hazard Distance (NOHD).
An 80 W CO₂ laser has a shorter NOHD of less than 1 km, due to lower hazard from its wavelength and more beam spread.
Using a lens to focus the laser reduces these distances:
The NOHD for a 20 W fibre laser is reduced to about 25 m.
For an 80 W CO₂ laser, it's under 5 m.
Thus, safety measures are necessary within these distances, such as blocking or enclosing the beam. Although full enclosure is ideal, it’s often impractical in production. Instead, beam stops and diffusely reflecting panels are used to contain hazards:
Diffuse reflections spread light like a bulb, reducing hazard range significantly to about 350 mm and 200 mm (fibre and CO₂ lasers respectively) when viewed head-on, and under 100 mm from the side.
With carefully designed barriers, panels, interlocks, and procedures, safe laser workspaces are achievable.
Laser safety classification system
The laser safety classification system categorizes lasers based on risk, with standards in Europe (EN60825-1) and the U.S. (ANSI Z136.1). Here’s a summary of the classes:
Class 1, 1M, 1C: Safe under typical operating conditions. Includes high-power lasers that are fully enclosed to prevent exposure to hazardous radiation.
Class 2, 2M: Emits only visible light. Eye protection relies on natural aversion responses, like blinking.
Class 3R: Can cause injury with prolonged or intentional exposure but is generally low-risk.
Class 3B: Direct viewing is hazardous, but diffuse reflections are usually safe. May cause minor skin injuries or ignite flammable materials.
Class 4: Hazardous even with diffuse reflections. Can cause skin injuries and pose fire risks, requiring strict safety measures. Most industrial lasers are Class 4 but can be treated as Class 1 if properly contained and controlled.
The Role of Laser Safety Officers:
A Laser Safety Officer (LSO) is a trained individual responsible for overseeing and ensuring the safe use of lasers in an organization. This role is critical in environments where lasers are used for industrial, medical, research, or educational purposes.
The Laser Safety Officer (LSO) is responsible for:
Coordinating the acquisition of laser devices and systems.
Ensuring all lasers comply with safety standards.
Implementing engineering and administrative controls, including personal protective equipment, with a Standard Operating Procedure (SOP) and laser safety manual.
Recording and reporting laser-related accidents.
Conducting regular safety inspections of laser areas and equipment.
Providing training, educational resources, and proficiency assessments for personnel.
Maintaining an up-to-date inventory of all lasers within the organization.
Assisting in investigations of laser-related incidents.
The role of an LSO is crucial for creating a safe work environment, preventing accidents, and ensuring proper handling of lasers. This position is required in many settings to meet regulatory guidelines, protect personnel, and minimize liability associated with laser hazards.
Conclusion
In conclusion, as lasers become more accessible and widely used in various industries, understanding and managing the associated safety risks are essential. The hazards of lasers—particularly the risks to vision and potential for long-term eye damage—demand strict adherence to safety standards, effective risk assessments, and proper training for all personnel involved. The laser safety classification system helps categorize risks, guiding necessary precautions, while the role of the Laser Safety Officer (LSO) is vital in ensuring compliance, safe practices, and protection for all laser operators. By following these guidelines and implementing robust safety measures, industries can harness the power of lasers effectively and responsibly within safe working environments.
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