Research on near-field distributions of axisymmetric folded-combined CO2 laser

The near-field-intensity distributions of diffusion-cooled axisymmetric folded-combined CO2 lasers are investigated. Formulas representing the near-field distributions for some typical kinds of folded-combined CO2 lasers are suggested, and the near-field-intensity profiles are calculated numerically and simulated. For several centimeters from the output mirror along the direction of the symmetric axis, the intensity in the output beam is very high and its radius (or width) is very small (approximately double waist radius). The frequency differences between different cavities would induce fluctuations of the intensity distribution, but the fluctuations are not distinctive. The near-field beam can be used directly in some industrial material processing.