Laser classes
Laser-based warning systems are used in industrial applications to visibly mark hazard zones or traffic routes. For example, they can project lines, symbols or zones directly onto the floor or other surfaces and are used, amongst other things, on industrial trucks and machinery.
As laser radiation can pose a risk to the eyes and skin depending on its power, wavelength and exposure, laser products are categorised into different laser classes according to their hazard potential.
Overview of laser classes (in accordance with DIN EN 60825-1)
| Class | Meaning | Safety information |
|---|---|---|
| Class 1 | Under the specified operating conditions, the accessible laser radiation complies with the limit values for Class 1. | Safe when used as intended. |
| Class 1M | Safe to the naked eye under intended conditions. A hazard may arise when viewed through optical instruments. | Do not look into the beam through optical instruments. |
| Class 1C | Laser product for applications in which the laser radiation comes into contact with the intended target as intended. Technical measures prevent hazardous radiation outside the intended contact area. | Use only in accordance with the intended application. |
| Class 2 | Visible laser radiation from 400 to 700 nm. In the event of brief, unintentional exposure of up to 0.25 s, the risk is limited by natural avoidance reactions. | Do not look directly into the beam. |
| Class 2M | As for Class 2; however, viewing through optical instruments may pose an additional hazard. | Do not look into the beam through optical instruments. |
| Class 3R | Direct exposure of the eye may be hazardous. The risk is limited compared with Classes 3B and 4. | Avoid direct exposure of the eye to the beam. |
| Class 3B | Direct laser radiation is hazardous to the eye and, depending on power and exposure, may also pose a risk to the skin. Diffuse reflections generally present a significantly lower risk. | Appropriate protective measures are required. |
| Class 4 | High risk to the eyes and skin. Even diffuse reflections can be dangerous; there may also be a risk of fire. | Comprehensive technical, organisational and, where necessary, personal protective measures are required. |
For freely accessible warning and projection systems, lower laser classes are particularly relevant due to the lower risk potential. As the laser class increases, so do the requirements for the necessary technical, organisational and, where appropriate, personal protective measures.
What criteria are used to classify lasers into classes?
Lasers are classified in accordance with the international standard DIN EN 60825-1. The focus is not solely on power output, but on a comprehensive risk assessment. Five factors in particular are decisive for the classification of lasers:
- Firstly, the output power plays a key role – that is, how much energy is emitted per unit of time. The higher the power (measured in milliwatts), the greater the potential risk.
- Secondly, the wavelength is relevant: only visible radiation between 400 and 700 nanometres provides natural protection through the blink reflex. Invisible infrared or UV radiation, on the other hand, can be dangerous without the eye reacting.
- Thirdly, the duration of exposure is taken into account. Short-duration pulses may be less critical than continuous exposure at the same power.
- Fourthly, the beam geometry plays a role – a highly collimated beam has a significantly higher energy density than a widely divergent one.
- Finally, the standard also assesses the possible use of optical aids such as magnifying glasses or cameras. Laser sources in Classes 1M or 2M, for example, are safe when viewed directly with the naked eye, but can cause damage when viewed through a magnifying device. All these criteria together determine which laser class a product falls into and what protective measures are necessary.
Safety requirements and instructions
- Labelling requirements:
Laser products are subject to specific labelling and information requirements depending on their laser class and design. These may include details of the laser class, warning notices and appropriate warning symbols. - Installation & Alignment:
Laser-based warning systems should be installed and aligned in such a way as to prevent unintentional direct exposure of persons to the laser beam. - Visibility vs. Safety:
Lower laser classes limit the accessible laser radiation and thus the potential for direct hazard. However, even with Class 2, direct exposure as well as possible glare and after-image effects should be taken into account. - Training & documentation:
Users should be informed about the safe handling of laser-based warning systems and about potential hazards. The manufacturer’s specifications and the protective measures required for the specific application are decisive in this regard.
Laser class vs. photobiological safety
For conventional lamps and LED light sources, photobiological safety is assessed in particular in accordance with DIN EN 62471. Laser products, on the other hand, are generally covered by DIN EN 60825-1 and are assigned to a laser class according to their accessible laser radiation.
Both sets of standards use different assessment and classification procedures. Under certain conditions, however, DIN EN 60825-1 also provides for the photobiological assessment of certain laser-based light sources in accordance with the IEC 62471 series of standards. Laser classification and photobiological assessment are therefore not fundamentally mutually exclusive.
FAQ: Laser classes for warning systems
What is laser class 1?
Class 1 lasers are considered safe under normal operating conditions. The accessible laser radiation is below the maximum permissible irradiation values (MZB) and poses no danger to eyes or skin.
What does laser class 1M mean?
Class 1M lasers are not dangerous when viewed directly with the naked eye. However, the use of optical instruments such as magnifying glasses or binoculars can increase the risk as they focus the radiation.
What characterizes laser class 2?
Class 2 lasers emit visible light in the range from 400 to 700 nm. Short-term exposure (up to 0.25 seconds) is considered safe for the eye due to the natural blink reflex.
What is the difference between class 2 and 2M?
Class 2M lasers are similar to class 2, but the use of optical instruments can increase the risk. Without such aids, they are also classified as safe for short-term exposure.
What does laser class 3R mean?
Class 3R lasers can be dangerous to the eye, especially when viewed directly. The accessible radiation exceeds the MZB values for the eye, but remains below the values for class 3B.
What are the dangers of class 3B lasers?
Class 3B lasers are dangerous to the eye and can also damage the skin when directly irradiated. Diffuse scattered radiation, however, is considered harmless.
What must be observed with laser class 4?
Class 4 lasers pose a high risk to eyes and skin. Even diffuse reflections can be harmful. There is also a risk of fire or explosion.