Laser Safety FAQ - Frequently Asked Questions

Laser Class 1

Class 1 lasers are, under normal circumstances, not hazardous, even when viewed with optical instruments. If the radiation is accessible, it is so weak, that no damage can occur to the human eye. If the radiation is hazardous, then it is encapsulated in a way, that it is inaccessible - even when the device is manipulated.
Note: Cutting lasers are usually encapsulated in such a way, so the device is rated class 1.

Laser Class 1M

Class 1M lasers emit a beam of 302.5 to 4000nm, which is either widened, or divergent.
For the whole beam the limit is 500mW (limit for class 3b). The pupil cuts only a portion of the beam, this portion does not exceed the limit of class 1.

When viewed with optical instruments class 1M lasers can be dangerous. Viewing with a loupe or a telescope/binocular can reverse the widening/divergence of the beam and thus exceed the limit for class 1.
Glasses are not considered optical instruments in this regard.
The manufacturer has to indicate which optical instruments can be dangerous

Laser Class 1C

Laser class 1C has been newly established in IEC 60825 version 07-2015 and covers laser systems that are designed for direct contact with the "objective", like e.g. the skin.
This can be laser systems for hair removal, reduction of wrinkles, tattoo removal and treatment of akne. Included are laser systems for home use as well.
Protection measures for these laser systems must ensure to not allow any emission of radiation that exceeds the level of laser class 1. Usually the laser class 1C units have special contcat sensors that prevent laser emission if the laser is not used in a safe way. The electrical conductivity of human skin is often used for these kind of safety measures.

Laser Class 2

Class 2 lasers emit only visible radiation not exceeding 1mW power. Accidentally looking into the beam does not create damage to the eye, even when using optical instruments.
Warning: Looking into the beam intentionally may be dangerous (as the reflex of closing the eye or turning away is not working)!

Laser Class 2M

Class 2M lasers emit a visible beam (400-700nm), which is either widened or divergent.
The limit for the whole beam is 500mW (limit for class 3b). The pupil cuts only a portion of the beam. This portion must not exceed the limit of class 2.

When viewed with optical instruments class 2M lasers can be dangerous. Viewing with a loupe or a telescope/binocular can reverse the widening/divergence of the beam and thus exceed the limit for class 2.
Glasses are not considered optical instruments in this regard.
The manufacturer has to indicate which optical instruments can be dangerous.

Laser Class 3R

Class 3R emit a visible beam (400-700nm) that does not exceed 5 times the limit of class 1 for invisible, or 5 times the limit of class 2 for visible radiation (=5mW).
R stands for relaxed, lasers of class 3R do not require the same safety measures as lasers of class 3b and 4 do.
Warning: Class 3R lasers can damage the eye, even when only looking into the beam for a short time. Do not look into the beam!

Laser Class 3B

Lasers of class 3B emit in continuous wave mode a power of maximum 500mW. Direct viewing of the beam will cause damage to the eye!
When viewing the image of the beam/spot on a diffuse reflecting wall, the eye will not be damaged. (Distance to the spot 13cm, viewing time less than 10sec.)
Warning: Class 3B lasers can damage the eye, even when only looking into the beam or into specular reflections for a short time. Do not look into the beam!

Laser Class 4

All other lasers are class 4. There is no limit for class 4 lasers. Beam, specular reflections and diffuse reflections can very dangerous for both eyes and skin!
When viewing diffuse reflections, the MPE level of the reflection has to be assessed. 
Class 4 lasers can damage eye and skin by direct or indirect radiation!
The radiation of class 4 lasers can release toxic fumes from certain materials and ignite inflammable or explosive materials.