High-power lasers are used in, among others, surgery, industry, and light effects at concerts and discos. Less powerful lasers are used in various measurement devices and targeting equipment. Many are probably familiar with the use of small lasers as pointing devices. 

Why can lasers be dangerous?

A laser beam travelling through the air has a very long range because it does not diverge like a regular beam of light. The danger of a laser beam is that it can concentrate a great amount of energy in one small area. When carrying out surgery or in industrial applications, for example, a powerful laser beam burns and vaporises tissue and other material. This is why a powerful laser beam hitting the eye or skin can cause permanent injury. In particular, lasers which work on the wavelengths of visible light and near-infrared radiation are able to cause permanent damage to the retina of the eye.

The most important safety requirement is that laser beams are not directed towards people. When using a laser device, installation and operational instructions, and other safety regulations must be adhered to. 

Safety classes of laser products

Laser products are divided into safety classes, with the more dangerous products having a higher number. The current system contains the following classes: 1, 1M, 2, 2M, 3R, 3B, and 4. The letters signify the characteristics of the laser beam.

Class 1: The laser beam in class 1 laser products is so weak that it poses no threat in any situation, or when the product is designed so that the laser beam is limited to the inside of the device. A laser encased in a device can however still be powerful enough to qualify as a higher class of laser. This is the case with CD players, for example. These kinds of laser products have warnings not to open the protective case. Toys shall not be over class 1 laser products.

Class 2 laser products only produce visible light and are relatively low power. The maximum output power for class 2 laser products is 1 mW. Usually the blinking of an eye is enough protection for it. Staring at a laser beam that is part of this class however, can damage the eye. The most powerful laser pointers permitted in Finland , and lasers used educationally in schools belong to this class.

Class 1M and 2M: The beam of laser products which are class 1M and 2M has a large divergence or it is relatively wide at the source of the laser output. Looking at a class 1M or 2M laser can only be dangerous when using a radiation gathering optics, such as a pair of binoculars or a magnifying glass.

Class 3R lasers are slightly more powerful than classes 1 and 2. In the visible range the maximum output power for class 3R lasers is 5 mW. A direct hit or a reflection from a smooth surface can cause permanent damage in the eye. Some directional and levelling lasers, for professional use, belong to this class.

Class 3B: A beam hitting directly or reflected on a mirror that is a class 3B laser is always dangerous for the eyes. The maximum output power for class 3B lasers is 500 mW.

Class 4: The beam of a class 4 laser is so powerful that it can instantaneously burn the skin. The eye can be damaged even from a diffused reflection. A high-power laser can set wood or canvas alight. Class 4 laser products are used in places such as hospitals, in industry as cutting equipment, and in certain show performances as a lighting effect.

Laser products which run on batteries must be checked beforehand

Finland has set limits on the importation of laser products which run on batteries. The lasers in question must be type inspected before they can be sold, handed over to another party, or taken into use in Finland. Laser equipment must be accompanied by a certificate of type inspection. It is not enough for a battery-powered laser device to have a CE mark. Manufacturers of laser products which run on mains power must be able to show, if necessary, that it fulfils all the requirements of the relevant directives.

The necessary type inspection of the laser product can be carried out in Helsinki by the Finnish Institute of Occupational Health,. A requirement for approval is that the laser product has the necessary warning signs, safety class labels , and approval marks, and that the user instructions are in Finnish and Swedish.

Surveillance of laser display products

STUK inspects high-power laser products (classes 3B and 4) which are used in public displays, before they are taken into use. The operator has always a duty to present the device on-site to STUK for inspection before being taken into use.