Noncavity copper vapor laser generating high-quality radiation

An investigation was made of the characteristics of radiation generated by a copper vapor laser operating in the superradiant regime and having a single convex mirror. An LG-201 commercial sealed active element was used, together with an experimental element having a discharge channel longer by a factor of 1.4. Highly stable radiation was obtained with characteristics which could be controlled by changing the mirror radius. For mirror radii two or three orders of magnitude smaller than the distance from the mirror to the exit aperture of the active element, the divergence angle of the beam was close to the diffraction limit. Average radiation power densities of 1–10 MW/cm² could be achieved in a focal spot. This is more than two or three orders of magnitude higher than those obtained in a plane–plane resonator. The energy per pulse, the peak power, and the axis of the radiation pattern were several times more stable than for an unstable resonator, and the intensity distribution in the focal plane was also more uniform. These advantages should improve the quality of high-precision materials processing.