Measured beam deformations in a guide made of tubular gas lenses

We discuss problems connected with the alignment of gas lenses and present experimental results showing the effects of off-axis injection of a light beam into a beam waveguide (offset a/r ≦ 0.315, r = radius of tubular lens) and of the introduction of various radii of curvatures (R ≧ 500 m) on the shape and position of the transmitted Gaussian beam. The theoretical prediction of reduced beam distortions for nonconfocal geometry was confirmed experimentally. We demonstrated low losses at small bending radii by using 12 lenses as focusing elements within a laser cavity in the bent state.