Beam Quality enhancement for unconventional laser formats

In this paper we review the general problem of Optical Beam Quality for beams that are not simple axial symmetric gaussian beams. We discuss the theoretical studies and experimental results obtained on the beams emitted by compact, medium power, diffusion cooled CO2 lasers and laser arrays. Our case-studies include a linear array of 9 CO2 lasers and an annular laser aperture with array-like emission produced by a Talbot cavity. We show that aspects of beam propagation that were founded on Gaussian beam theory need to be re-evaluated when considering these more complex beams. For example different polarization states in array elements lead to different field distributions in the far field and thus to a different beam quality. Furthermore we comment on the limited information given for such structured beams by traditional Beam Quality Factors, such as M-2, established for nearly-Gaussian beams.