5. Thermal effect

The thermal action of lasers is now the predominant mechanism of therapeutic laser applications. The thermal effect encompasses a broad group of interaction types characterized by a significant temperature change within the tissue illuminated by the laser. Thermal effects can be achieved with both continuous and pulsed lasers. The thermal effect of lasers is a complex process comprising three phenomena: conversion of laser light into heat, heat transfer to the tissue and a temperature-dependent tissue reaction. Depending on the duration of heating and the temperature rise in the tissue, one of the following effects can be obtained: hyperthermia, coagulation, or volatilization of a given tissue volume (table 1 ).

There are a huge number of clinical applications, and it is beyond the scope of this article...