Universal system for extracting radiation from a gas-laser cavity

The design of a universal radiation-extraction system that can be used for extracting radiation from a gas-laser cavity in three different ways is described. The three variants encompass radiation extraction through a two-way or a centrally perforated mirror, radiation extraction from an unstable cavity, and radiation extraction as a result of Fresnel reflection from the surface of a transparent plate. Technological requirements of each variant are reviewed, radiation extraction as a result of Fresnel reflection is examined in detail, and focusing of radiation extracted in this way is discussed. It is noted that the described universal radiation-extraction system has been tested and successfully operated with a CO2 laser.