Gaussian beams Theory and measurements

Given the growing importance of Gaussian beams in a wide range of applications, their study requires special attention. This article presents not only the theoretical aspects of the fundamental Gaussian mode, but also measurement techniques for characterizing the quality of Gaussian beams.

The first part sets out the characteristics of these beams very progressively, taking care to separate Gaussian attenuation and the evolution of wave surfaces with propagation. Too often, these two aspects are intertwined, giving a mathematical rather than a physical appearance. Then, the influence of characteristics on each other is studied, in particular through the notions of intensity and luminous power. Finally, analysis criteria and beam quality coefficients are defined to bring this first part to a close.

A second section, building on the results of the previous section, is devoted to experimentation and measurement on Gaussian beams. Techniques commonly used in the laboratory and more recent, more computerized ones are explored to give the reader a wide range. Quality standards and measurement procedures for Gaussian beams are also introduced.

A number of illustrations and numerical examples are provided for better understanding. A glossary and table of symbols are included at the end of the article.

The article [E 4 043] follows, with the first part devoted to optics adapted to Gaussian beams in the paraxial frame, using matrix optics. This is followed by a second, applicative section describing commonly used stable linear resonant cavities and some applications of Gaussian beams.