The modern phototherapy uses several types of sources of light, which are different in their physical properties and effects on a living organism. While some of them are known to us from medical offices for decades (especially SoLux or the sunlamp), others have been used by the medical science more extensively only in the last years.

The laser is an acronym, which stands for "Light Amplification by Stimulated Emission of Radiation". Lasers, which rank among the most significant discoveries of the 20^th century, are divided in medicine according to the output of the light ray into non-invasive (bio-stimulating) ones and invasive (surgical) ones.

A physically modified therapeutic laser ray differs from the light emitted by ordinary sources in several fundamental properties:

• it is MONOCHROMATIC (the light only has a single wavelength and therefore it has one colour)

• it is COHERENT (the rays oscillate in a phase accordance)

• it is POLARISED (the light waves oscillate in parallel planes, i.e. only in one direction).

·  These properties of laser allow for projecting the necessary energetic power of a light ray on a small area. In contact with a living tissue, it supports healthy development of cell structures. This effect is most frequently referred to as bio-stimulation. However, the spreading of the laser therapy outside of medical offices was prevented by its high price and strict safety and hygienic standards because if laser is handled in an unqualified way, there is even a risk of permanent damage to health.

It was not until later when the results of a number of laboratory experiments with bio-stimulating laser ray brought a breakthrough in the process of spreading light therapy outside of medical office. These experiments proved that the course of bio-stimulation is fundamentally influenced mainly by its polarisation, which does not represent any health risk to the users of this therapy. This was why scientific teams proceeded to carrying out experiments, which were to prove that it was possible to achieve a comparable bio-stimulating effect even with some other source of polarised light. The result of these efforts was a substantially simpler, cheaper and yet sufficiently effective source of therapeutic polarised light known as bioptron lamp .