Laser classes - definition and classification

Safety should always be a top priority when working with laser systems. Laser classes were created to help identify the level of danger coming from different types of laser beams. There are four different laser classes from 1 - 4 (with additional subclasses) that separate the devices. These range from absolutely harmless (“innately safe” = laser class 1) to highly damaging to eyes and skin (laser class 4.)

What makes a laser dangerous?

The variability of a laser is highly useful for processing material, but it can be destructive to biological tissues. A laser capable of cutting incredibly dense material is also capable of burning biological tissue or causing irreparable eye damage. This makes laser safety crucial.

The individual laser classes:

Class 1 - Not dangerous

Class 1 lasers are not dangerous under normal operating conditions. This means that the power radiating from the beam is very low or the laser system is enclosed in a way that does not allow radiation to escape.

Class 1M

For class 1M lasers, the accessible laser radiation is in the wavelength range of 302.5 nm to 4,000 nm. In this laser class, as long as the cross-section of the beam is not reduced by additional, optical instruments - such as lenses or telescopes - there is no danger to the human eye. Without optical reduction, the hazard potential of class 1M devices is the same as class 1.

Application:

  • Barcode readers, for example at supermarket checkouts

Class 2

For class 2 lasers, the accessible laser radiation is between 400 nm and 700 nm and thus in the visible spectral range. Class 2 lasers are not dangerous to the human eye if exposure is limited to less than 0.25 seconds. It is possible to operate these laser systems without additional protective equipment - as long as the operator does not regularly look into the beam for more than the recommended limit of 0.25 seconds to operate the laser.

Laser class 2 is the most underestimated laser because, though it is generally safer to operate than a class 4 laser, staring directly at the beam for more than 0.25 seconds can result in permanent (!) eye damage. Human eyelid closure reflexes or aversion reactions are not (!) present in these types of beams in 4 out of 5 individuals. Properly classified laser class 2 lasers are not toys and should be used responsibly.

Application:

  • Laser pointers
  • Laser spirit levels
  • Light curtains

Class 2M

For class 2M lasers, the accessible laser radiation is in the visible spectral range from 400 nm to 700 nm. Similar to class 2 lasers, it is only dangerous to the eyes if you look directly at the beam for more than 0.25 seconds. When using optics that reduce the cross-section of the laser light, you may see similar hazards to classes 3R and 3B.

Application:

  • Projection laser, for example in laser shows or an exhibition stand construction

Class 3R

For class 3R lasers, the laser radiation in the visible wavelength range is from 380nm to 780nm at a maximum of 5mW. This is five times greater than for laser class 2. This laser class forms the transition between laser class 2 and 3B. These lasers can cause eye damage! These lasers should only be operated by individuals who know of the risks. However, it is not required by law to receive laser training.

Application:

  • Target devices or distance measurement
  • Leveling lasers
  • Large-scale light curtains

Laser safety goggles - depending on the wavelength and power of the laser, there are different versions, recommended from and incl. laser class 3, mandatory for laser class 4

Class 3B

The radiation emanating from a class 3B is dangerous to both the eyes and the skin. Avoid looking directly into the laser beam at all costs. Looking at the laser beam through a protective barrier is possible, provided that there is a minimum distance of five inches between screen and cornea, the maximum viewing time is less than 10 seconds, and no beam refractions can directly hit the eye. Class 3B devices are dangerous to the skin if you exceed the maximum permissible radiation values.

Application:

  • Cosmetic lasers
  • Show lasers

Class 4

Only professionals should use class 4 laser systems. The radiation emanating from the laser can be incredibly damaging to the eyes and skin, even if it is diffused or scattered. Additionally, these types of lasers can cause a fire risk. Class 4 lasers are high power lasers for material processing. The output power of these lasers is unlimited, unlike class 3B and lower systems. The laser beam of class 4 devices is strong enough to damage eyes or skin as soon as it comes in contact. In the private sector, these lasers can be purchased and operated at home. However, we advise against use without proper knowledge and training in favor of the safety of you and others! It is possible to suffer eye damage even at several hundred or thousands of feet away. Depending on the wavelength, the laser can also pass through windowpanes without significant absorption.

Application:

  • Laser cutting machines
  • Laser welding machines
  • Science and research
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