Introduction to Laser Safety

by Mar 26, 2024Hazardous materials, Machine Safety

The term is an acronym of light amplification by stimulated emission of radiation. The technologies at the source of laser beams used in industry are complex, but they boil down to a light source in a reflective medium that focuses and directs the light in a single direction. The important concept to understand in terms of machine safety is that since all the radiant energy of a laser is concentrated in a single point, it can be high and hazardous.

The main industrial applications of lasers are:

  • Measurement (laser thermometer, laser ruler, laser level, etc.);
  • Laser welding;
  • Laser cutting; and,
  • Laser engraving.

Identification of Laser Classes and Hazards

Since 2007, lasers are classified according to the IEC 60825-1 standard. Care must be taken when looking at the laser classes, as the class indicated does not depend on the source, but on the product as a whole. The class indicated includes the guards in place and the intended mounting. If you change the guards or the mounting so that the worker is now exposed to the source, the class may no longer be valid. For example, if you install a laser engraver 10 feet in the air or pointing up instead of down, the worker is exposed to laser energy that exceeds the class specified by the engraver manufacturer.

Here is a summary of the different laser classes:

  • Class 1: The laser is safe to use. Viewing directly and through an optical device for a long period is safe. The class also includes high-powered lasers that are totally enclosed so that no potentially harmful radiation is accessible;
  • Class 1M: The laser is safe for direct vision for a long period of time. Eye damage may occur after exposure through an optical device;
  • Class 1C: Laser devices intended for application to human tissue, e.g., laser hair removal, laser surgery, etc. These devices are considered safe if used according to established procedures, although they may also be of Class 3R, 3B or 4;
  • Class 2: The laser is safe for short-term exposure, e.g., 0.25 s, but may cause eye damage if deliberate staring into the beam. The laser beam is visible.
  • Class 2M: The laser is safe for short-term exposure only. Viewing through an optical device is hazardous. The laser beam is visible.
  • Class 3R: Laser that emits radiation that exceeds the MPE (Maximum Permissible Exposure). The risk of injury increases with exposure.
  • Class 3B: Hazardous laser when ocular exposure of the beam or direct reflection occurs. Accidental short-term exposure is hazardous. Viewing diffuse reflections is normally safe.

Importance of Adequate Safety

The main causes of accidents related to lasers are:

  • Exposure to beams during alignment or assembly;
  • Inadequate or unused eye protection;
  • Inadequate beam containment;
  • Poor design and use, e.g., exposure to hazardous direct or diffuse reflection; and,
  • Laser glare.

It is important to check the safety of one’s installations with regard to exposure to laser radiation and to use laser tools correctly. The class of the laser should not be relied upon alone. Improperly positioned Class 1 lasers could dazzle a forklift operator or machine operator and cause an accident. The use of laser safety glasses may be insufficient if the laser is hazardous to the skin. The use of a laser engraver that appears to be safe and is installed in accordance with the manufacturer’s intended class may be hazardous when the material is reflective and causes the laser to beam towards workers. A guard with the wrong properties could allow some of the radiation to pass through. It is therefore advisable to assess the safety of lasers in your installations.

 

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Intervention Prévention Inc.

Intervention Prévention œuvre dans le domaine de la sécurité au travail en offrant des services spécialisés répondant aux normes CSA Z462 – Sécurité électrique en milieu de travail, CSA Z460 – Maîtrise des énergies dangereuses : Cadenassage et autres méthodes, et CSA Z432 – Protection des machines. Nos domaines d’expertise sont donc reliés au cadenassage, à la sécurité électrique et à la sécurité machine. La satisfaction de nos clients est le gage de notre compétence

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