Longitudinally excited short-pulse CO2 laser with large discharge tube without preionization

A longitudinally excited CO2 laser with a large discharge tube having an inner diameter of 16 mm and a length of 80 cm produced short laser pulses with an energy of 38.1 mJ at a repetition rate of 700 Hz. The CO2 laser did not have a preionization system or a fast gas flow system. The dependence of the laser output and discharge voltage on the repetition rate, the gas pressure and the structure of the discharge tube in 1:1:4 and 1:1:2 mixtures of CO2/ N-2/He gas was investigated. At a repetition rate of 300 Hz or more, the laser energy decreased as the repetition rate increased. The 1:1:4 mixture of CO2/N-2/He gas produced a higher laser energy than the 1:1:2 mixture of CO2/N-2/He gas. At a repetition rate of 300 Hz or less, the laser beam profile was doughnut-shaped. At a repetition rate of 400 Hz or more, the center of the laser profile had a high energy. At a high repetition rate, the fast discharge may have collected in the center of the discharge tube. Moreover, an increase in the repetition rate decreased the discharge formation time and the energy of a pulse tail part of the laser pulse waveform.

Automated summary

This study investigated the dependence of laser output and discharge voltage on repetition rate and gas pressure by using a longitudinally excited CO2 laser with a large discharge tube. It was found that the laser energy decreased with increasing repetition rate and different gas mixtures had an impact on laser output.