GENERATION OF CO2-LASER PULSES BY Q-SWITCHING AND CAVITY DUMPING AND THEIR AMPLIFICATION BY A MICROWAVE EXCITED CO2-LASER

Q-switched low-pressure CO2 lasers allow both the production of maximu m laser pulse power and high average laser power at high pulse repetit ion rates. A Q-switched CO2 laser oscillator amplifier system consisti ng of a DC discharged, wavelength tunable and diffusion cooled oscilla tor and a microwave excited amplifier is described. By mechanical Q-sw itching of the oscillator laser pulses with a pulse repetition rate of 4-200 kHz and TEM(00) beam quality can be produced. After the amplifi cation the peak power reaches 0.9 MW at a pulse repetition rate of 10 kHz and 0.2 MW at a 100 kHz repetition rate. The pulse duration (FWHM) is about 0.2 mu s. The maximum average power of 7 kW in the Q-switche d mode reaches nearly the maximum cw laser power of 10 kW (with TEM(00 ) beam quality). The laser pulse duration can be shortened by the comb ination of cavity dumping and electro-optical Q-switching. This pulsed operation leads to laser pulses with 35 ns pulse duration and 1.9 MW maximum power at a pulse repetition rate of 10 kHz and an average lase r power of 0.8 kW. The self-oscillation of the oscillator amplifier sy stem can be suppressed by an optical shutter between oscillator and am plifier. The laser beam power can be calculated by a six-temperature m odel including rotational relaxation, intramode and intermode vibratio nal energy exchange.