Basic principles of lasers

The word laser is an acronym of Light Amplification by Stimulated Emission of Radiation. A laser emits a beam of electromagnetic radiation that is always monochromatic, collimated and coherent in nature. Lasers consist of three main components: a lasing medium (solid, liquid or gas), a stimulating energy source (pump) and an optical resonator; and have a wide variety of uses in clinical medicine. Lasers cause tissue damage by various mechanisms and these are mainly determined by power density (irradiance) of the beam and exposure time. It is imperative to be aware of the risks associated with laser use in terms of tissue damage (burns and eye injuries) and fire hazards. Strict controls should be implemented governing the safe use of lasers in hospital practice, and all staff must be familiar with all safety measures to prevent injury and fires.