Beam quality of a high-power CO2 laser MOPA system

In this paper, the effects of amplification of diffraction-limited pulsed CO2 laser radiation over several meters of amplification length on beam quality and pointing stability are documented. Millijoule pulses are amplified up to 3 J. Generation and amplification of the 10 mu m wavelength pulses were performed in the discharge volume of an e-beam sustained CO2 laser. Beam quality is measured according to the ISO/DIS 11146 standard in terms of the beam quality factor M-2. Fluence distributions were recorded with a beam analysing system of 100 mu m spatial resolution. M-2 parameter values ranged up to 1.55 for amplified pulse energies of 3 J. The necessity of beam-quality restoring techniques is inferred for the multijoule pulse energy regime. (C) 1999 Elsevier Science Ltd. All rights reserved.