Performance of a 80Â W copper vapor laser with “alignment free” unstable CAT-EYE resonator and other configurations using intra-cavity apertures

Off-axis unstable CAT-EYE unstable resonator was also demonstrated for the first time with further reduction in beam divergence to ∼0.13 mrad and with output power of ∼28 W. The misalignment tolerance was found to be highest in case of off-axis unstable CAT-EYE resonator with decline/drift in laser power of only ∼10% for misalignment angle as high as ∼8 mrad. Performance with intra-cavity apertures in plane-plane type CAT-EYE resonator for transverse mode control is also presented for the first time in CVLs. It is observed that the laser beam divergence reduces significantly to 1.25 mrad (a factor of 2) on using an aperture of ∼3.5 mm at the CAT-EYE reflector as compared to its normal (R = F = d) configuration without aperture. In case of stable CAT-EYE resonator the average beam divergence reduces from 8 mrad to 4 mrad (factor of 2) on using intra-cavity aperture of about 3 mm. It was also observed that high misalignment tolerance was retained on using intra-cavity apertures in almost all the CAT-EYE resonators. Use of intra-cavity mesh was also demonstrated for the first time with stable CAT-EYE resonator for improving the beam focus-ability. Average beam divergence was reduced by a factor of 2.5 (from 8 mrad to 3 mrad) on using intra-cavity mesh. These new configurations in CAT-EYE resonators in KE-CVLs are found to be effective in improving and controlling the laser beam divergence significantly with additional characteristic of high misalignment tolerance.