Laser Safety Basics for Laboratories
Workplace Noise Measurement Can Be Easier
A laser environment in a laboratory should reflect rational and deliberate economic choices that mitigate an identified sea of potential hazards. This article presents an overview of safe laser management in a lab environment. Hopefully, it will take you one step closer to creating a safe laser environment that meets the requirements of end-users with the demands of a laser safety program.
Laser Beam Safety The safest beam direction is usually straight down. Ideally, laser beams point down, sometimes point horizontal, and rarely point up. Of course, even when the beam is carefully controlled, accidents can happen. A misaligned optic or a carelessly placed processing article may send a laser beam in unexpected directions.
Laser beams should stay on a worktable or within an enclosure. The open segments of a beam line should remain within a carefully controlled work area or enclosed space. In a controlled area, the beam never crosses pedestrian paths unless a beam tube or other device encapsulates the energy. Similar care should be taken when laser beam energy is directed to upper levels of an experimental setup.
Avoid horizontal beams at eye level when sitting or standing. Labs typically use optical tables with laser experiments mounted on top. Most optical tables are also at desk height, which means the eye level of a person at a workstation is usually in the same plane as the laser experiment. If the laser beam can’t be enclosed, laser barriers or beam blocks should be installed at the table perimeter to protect staff sitting at desks and workstations.
Laser Safety Standards According to ANSI Z136.1, Safe Use of Lasers, a laser safety officer (LSO) is “one who has authority and responsibility to monitor and enforce the control of laser hazards and effect the knowledgeable evaluation and control of laser hazards.” The LSO is designated by management and helps determine the required safety protocols to keep the lab safe. The LSO’s specific duties and responsibilities are outlined in ANSI Z136.1.
Another useful standard is ANSI Z136.8, Safe Use of Lasers in Research, Development, or Testing, which was updated in 2021. This standard is intended to provide guidance for the safe use of lasers in environments where the requirements of ANSI Z136.1 are not practical.
Laser Lab Entryway Controls ANSI Z136.1 requires one of three entryway control methods: 1. Non-defeatable. Non-defeatable safety latches, entryway, or area interlocks are used to deactivate the laser or reduce the output to a safe level upon entry.
2. Defeatable. Defeatable safety latches, entryway, or area interlocks can be temporarily overridden by authorized personnel if there is no laser hazard at the point of entry, provided they have been trained and have adequate personal protective equipment.
3. Procedural. In this case, safety latches or interlocks are not feasible or are inappropriate. All authorized personnel are trained and adequate personal protective equipment is provided upon entry. A blocking barrier, screen, or curtain is used to attenuate the laser radiation at the entryway, an area warning device is located at the entryway indicating that the laser is energized and operating at Class 4 levels, and the appropriate laser warning sign is posted.
When entering a lab, you should not see a laser source. Consider running a linear laser process line away from the door or installing guards or blocks on the end of your optical table. Laser eyewear should be available when entering a lab and is normally required by all entering usage areas for Class 3B (medium-powered) or Class 4 (high-powered) lasers.
Choosing the proper laser eyewear can sometimes present a challenge. To improve safety for all staff, first determine who will be allowed access to the lab. Next, evaluate options for containing the beam. Finally, choose eyewear appropriate for the laser hazard that does not unnecessarily impair working conditions. Non-Beam Hazards Certain non-beam hazards exist in most lab environments. Be sure to minimize trip and electrical hazards where possible. Do not forget air quality; some laser processes create hazardous fumes.
Pathogens should not pass through extraction systems shared with other users, and dust or heat in materials processing must be managed. Also, pay attention to the management of gases used to generate the beam or to enhance a laser process as pressurized gas presents explosion and combustion hazards.
Laser Lab Control Measures Control measures are designed to reduce hazardous levels of laser radiation to the eyes and skin. Engineering controls are the preferred method and include items such as interlocks, protective housing, area warning devices, and barriers, curtains, or enclosures—anything that is always in place for safety. If engineering controls are not practical, administrative controls and PPE controls should be implemented. Administrative controls include standard operating procedures, training on laser safety, restricting lab access to authorized personnel, and setting up a temporary laser-controlled area. PPE includes laser eyewear, face shields, and protective clothing such as gloves.
Laser Safety Tools The laser safety process involves identifying the hazards, analyzing and measuring the hazards, and managing or mitigating the hazards. Many tools are available for analyzing and managing laser safety hazards. Though not a comprehensive list, the following are some of the most common tools available to the LSO: • IR viewers allow for active viewing of the IR beam as it travels. IR viewers are useful when there is a strong chance that a beam is escaping a controlled area. Some models can be connected to or integrated with cameras and other video output devices.
• IR viewing cards and discs convert infrared radiation to visible radiation. Some IR cards store energy from a conventional light source, such as indoor room lighting or sunlight, which is released in the form of visible light when stimulated by IR radiation. Other IR cards use photosensitive materials.
• Ultraviolet viewers and viewing cards are similar to IR viewers, viewing cards, and cameras, but are sensitive to the UV range.
• Specialized coated or layered burn papers are available to visually display a laser beam’s size, shape, or mode structure. Depending on the type of burn paper used, either a cross-sectional image of the beam is etched or burned onto the surface of the product or a temperature change reveals the laser.
As you consider the complexity of laser safety, also realize that no one person can possibly know how to solve all laser safety puzzles. The laser safety community comprises smart, generous people willing to share their extensive knowledge with you. Be smart and connect with this network, examine the safety products available, and take a course in laser safety.
RICH GREENE is a laser safety specialist at Kentek Corp.
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