Abstract

High peak powers, varying pulse lengths and fast repetition frequencies are all desirable features of CO₂ laser beams for materials processing applications. Previous device configurations include the TEA laser, generating pulse lengths of ~l-5µs at a pulsed repetition frequency (PRF) to ~400 Hz, and radio frequency (RF) discharge excited diffusion cooled slab waveguide and fast axial flow lasers, which both offer both continuous operation and pulse lengths of 50-100 µs at 5kHz. However, recent developments in materials processing have led to an interest in devices that can deliver shorter pulses than the existing slab or fast flow lasers, but with a much higher PRF than the TEA laser. Fast pulsing of gas lasers requires the switch-off time of the laser to be short compared with the pulse length, a need that is often satisfied by an increase in intracavity pressure. Previous studies of diffusion cooled slab waveguide lasers have shown that operation is possible at high pressures, but that the required cooling of the narrow gap discharge limits efficient operation to pressures of ≤ 300 Torr.

© 1998 IEEE