Introduction

Lasers are now found in many sectors (optical telecommunications, storage of information (CD, DVD), instrumentation, measurement, biomedical, material processing). They are becoming increasingly reliable, compact and powerful. The range of applications will therefore expand. There are already so many that it is quite difficult to give an exhaustive list. However, they can be classified according to the properties of the laser radiation. As stated previously, it is a spatial, spectral and temporal concentration of light.