Abstract

The annular geometry represents an interesting alternative to the slab format for diffusion cooled RF excited CO₂ lasers. Typical draw backs of this scheme are related to the difficulties encountered in extracting a good quality beam [1] and in uniformly distributing the power in the discharge. Some effective solutions to the latter problem have recently been found [2,3], We have focused our attention to the former problem, experimentally testing the use of a Talbot cavity together with a phase-correcting mirror on the 100 W class annular laser described in Ref.[1]. The extraction efficiency obtained so far with this scheme is half that of a simple plane-plane guided resonator producing a multimode beam. The beam quality on the other hand appears sensibly enhanced.

© 1998 IEEE