Abstract: A new resonator concept which is especially useful in chemical laser applications is disclosed. A ring end mirror, a conical folding mirror and a circular end mirror are combined to form an unstable resonator including a radial direction propagation having a gain medium region and a region of axial direction propagation. Alternate embodiments of the invention include the use of nonreflective fins in the region containing the working medium to suppress superfluorescence and an aerodynamic window to keep depleted working medium out of the path of the resonant beam.