Class II Lasers (Low Risk)
Lasers emitting visible light which due to normal human reflex responses, do not represent
a hazard. However, a safety risk would be posed if the output source was brought within
close proximity of the eye and was then viewed for an extended period of time.
Class III Lasers (Moderate Risk)
Lasers that cause an injury of the eye if viewed temporary. They are not capable of
causing serious skin injury or hazardous and diffuse reflections without using
collecting/conditioning optics (e. g. fibre optics, telescope, etc).
Class IV Lasers (High Risk)
Lasers that present an eye hazard from direct and diffuse reflections. Such lasers can
cause combustion of flammable materials. In addition they may cause serious skin burns
and injuries from direct exposure.
For the class 4 lasers (more than 0.5 W) which we mostly use, following points are to be
considered and avoided:
1. Danger to the eye
A human‘s most sensitive organ is the eye. A laser beam is coherent,
monochromatic light with very high energy. A laser beam keeps its intensity
even on a large distance. If a laser beam hits a human eye, it could lead to
irreparable damages, the retina could be destroyed. Therefore the following
has to be considered:
Never look into a laser beam directly, and do not place any objects in
the beam, because even diffusely reflected beams will cause eye
damage. Never point the laser beam at a person’s eyes.
2. Danger of skin damages
If a laser beam hits the human skin, it will cause painful burns due to its high
energy density. The beam also burns holes into textiles. Therefore never put
your hands in the laser beam and do not intercept the beam with any
other part of your body.
3. Danger due to High Voltage
Laser systems use fatally high voltages. When operating your laser
system, always observe the warning notes on the laser and the
instructions concerning laser safety in the manual of your laser.
Make sure that no unauthorized persons have access to your laser
system.
4. Danger of fire damages
If a laser beam hits easily inflammable material, for instance paper, this will
ignite and may suddenly cause a fire. Therefore you should always make
sure that there is no inflammable material in the path of the beam before
[22]
Lasers emitting visible light which due to normal human reflex responses, do not represent
source was brought within
close proximity of the eye and was then viewed for an extended period of time.
Lasers that cause an injury of the eye if viewed temporary. They are not capable of
zardous and diffuse reflections without using
Lasers that present an eye hazard from direct and diffuse reflections. Such lasers can
able materials. In addition they may cause serious skin burns
For the class 4 lasers (more than 0.5 W) which we mostly use, following points are to be
monochromatic light with very high energy. A laser beam keeps its intensity
damages, the retina could be destroyed. Therefore the following
If a laser beam hits the human skin, it will cause painful burns due to its high
energy density. The beam also burns holes into textiles. Therefore never put
If a laser beam hits easily inflammable material, for instance paper, this will
