Lasers are powerful tools that are often used in labs requiring intense light sources to study or manipulate different kinds of materials. Due to the intensity of the light and the power of the laser beams, lasers present some significant hazards to lab staff. Especially for non-visible lasers, these risks can be unseen and not effectively addressed. Laser safety is defined by ANSI Z136.1, a widely recognized industry safety standard. Here are seven tips to help keep your lab safe when using high-power lasers:

Laser hazards

The direct hazards from laser beams in the lab are eye and skin damage. Laser light can cause severe damage to the eye, including retinal burns, cataracts, and blindness. Even indirect reflections can be sufficiently intense to cause significant damage. 

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The power of the laser beams can also damage other tissues, especially the skin. High-power lasers can generate severe acute burns and chronic burns on exposed skin.

Lasers also contain high-voltage power supplies and capacitors that present shock hazards. Lasers must be fully unplugged, locked out, and discharged before any repair or maintenance work is initiated.

Laser types and classifications

Lasers are categorized into four classes based on their power:

1. Class 1 lasers are completely safe under normal operation.
2. Class 2 lasers have low power and are only hazardous to direct observation.
3. Class 3 lasers are moderate to high risk to the eyes, and reflections can cause damage.
4. Class 4 lasers are high power and high risk, and even scattered reflections can cause damage.

Laser risks are also dependent on the wavelength of the light produced. Common lasers cover a wide range of wavelengths, like ultraviolet, visible, and infrared. Different wavelengths present different hazards to staff.

Beam path and exposure risk

To mitigate the risks of the laser, it is vital to map the beam’s path. Laser beams will travel in straight lines between optics, but all reflections from each optical surface must be mapped, understood, and contained. It is best practice to: 

• Shorten the beam path as much as possible
• Keep the height well below eye height for staff
• Remove any unnecessary optical elements
• Ensure all optical elements are rated for the power and wavelength of the laser
• Safely block or capture all reflections and the main beam at the end of the beam path

Nominal hazard zone

The ANSI standard defines the nominal hazard zone (NHZ) to be the area around the laser source that contains direct, reflected, or scattered laser light that can be hazardous to staff. Anyone working within the NHZ must wear appropriate personal protective equipment (PPE), especially laser protective eyewear chosen for the power and wavelength of the laser source. The NHZ can be reduced by containing the laser beam and removing all laser hazards from outside the containment. 

All staff members are required to understand where the NHZ is, with appropriate signage and barriers. No one should enter the NHZ accidentally or without the appropriate training and PPE. 

Containment methods

Laser beams can be contained by erecting barriers that completely absorb direct, reflected, and scattered laser light. A typical approach is to erect non-reflecting, often black, metal barriers around the beam path. It is important that these barriers contain all reflected and scattered light, so they may need to block reflections going up and down, as well as in the plane of the laser beam. Containing direct high-power laser beams may require more robust materials that can contain high-power beams for extended periods of time.

Laser safety officer

The laser safety officer (LSO) is responsible for all aspects of lab laser safety. These individuals require appropriate training and need to have a full understanding of the lasers used in the lab. An LSO is required by the Occupational Safety and Health Administration (OSHA) for organizations using class 3 and class 4 lasers. Key responsibilities include:

• Hazard evaluation
• Establishing control measures
• Approving procedures and modifications for lab activities using lasers
• Training staff using lasers
• Investigating any laser safety incidents
• Ensuring the lab is compliant with all laser standards and regulations

Laser safety training

It is vital that all staff using lasers are trained in:

• Their safe operation and use
• The PPE required when using the lasers
• How to safely shut down and discharge the equipment
• How to determine the beam path and contain reflections and scattered light
• How to keep other staff safe from accidental interaction with the laser beams

Lasers are powerful tools that are integral to many different lab activities, including analytical methods, characterization methods, and machining activities. While these tools contribute significantly to the lab’s capacity to make scientific discoveries, the intense light beams also create hazards that can burn or blind staff. Mitigating these risks is vital to using these tools appropriately.

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