[Photo-biomolecular effects of laser radiation]

The authors present the photo-biomolecular effects of laser rays by introducing their physical principles. The interaction between irradiated energy and matter is taken into consideration, by studying the wave length of the different types of laser, the emission and the energetic absorption. It is pointed out that the low-intensity laser radiations with given characteristics have no ionizing actions like X-rays or ultraviolet rays, and how the photo-biological and therapeutical action depends upon the absorption of rays and their diffusion.