抄録
A novel resonator, “Gauss-core resonator”, designed to yield a highly focusing beam wasapplied to a high-power cw CO2 laser. An output coupler has a circular partial-reflection regionin the center surrounded by an antireflection region. The phase difference betweenbeams passing through the two regions is structurally canceled out by the design of the outputcoupler. Main beam mode operating in TEM00 was determined by the partial-reflection regionexisting in the “core” of the output coupler. A diffraction beam spread from the center of theoptical path in the cavity is amplified by a laser medium. By combining part of the core beamtransmitted from the partial-reflection region with the amplified diffraction beam, a 6.2 kWdiffraction-limited output beam with the M2 factor of 1.7 was obtained. In laser materials processing, we can cut a 1 mm-thick mild steel with a cutting speed of 63 m/min at 5.9 kW.
