Multipass-resonators for compact CO2-lasers.

The application of CO2-lasers for example in medicine requires compact laser heads by preserving high output power. This results in the necessity of multiple paths of the beam through the excited medium. The linear and the spherical multipass-resonator satisfy these conditions with a small number of mirrors. By making use of special stability-diagrams, criterions for practical construction of such resonators can be elaborated. Thus the sensitivity according to tolerances of the mirror curvatures and distancer can be determined. The experiments with a linear multipass-resonator by using a RF-excited CO2-laser yield a power increase with increasing number of paths. A beam quality of 0.9 has been achieved with 5 paths. The optimal range of application of the linear multipass-resonator reaches to 100 W while the spherical multipass-resonator may also be adapted to hihger power. Here, the limits of power dimensioning are not yet reached in the experiments.