Improvement of the beam quality of a gasdynamically cooled CO laser with an unstable resonator by use of a cylindrical mirror.
The beam quality of a gasdynamically cooled CO laser with an unstable resonator (M = 1.7) has been improved by use of an extracavity cylindrical mirror. This mirror corrects the phase distortion resulting from the supersonic f low. A 4.5-kW laser beam with a total divergence of 1.4 mrad is obtained with an efficiency of 9% and a Strehl ratio of 0.4. A strong degradation of the beam quality has been observed outside the resonator owing to water-vapor absorption. The use of dry air in the beam-guiding system signif icantly reduces this effect of thermal blooming.
Schellhorn
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Büllow
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