[Physical and biophysical aspects of laser light]

The future applicability of lasers in medicine was evident when the first laser was developed some 30 years ago. Since then, laser-based techniques have been in continuous development in medical research, diagnostics and therapeutics. For example, the laser is used extensively today in ophthalmology, ranging from the well-established technique of photocoagulation of retinal vessels with blue light from continuous emitting argon ion lasers, through the more recently developed technique involving pulsed infrared emission from neodymium-yttrium-aluminum-garnet lasers for posterior capsulectomy, to more experimental modalities such as photo-refractive keratectomy using excimer lasers with ultraviolet emission. This paper briefly presents the physical basis of the laser, and discusses the basic mechanisms of interaction between laser emission and living tissues.