Studies on the pulsed UV lasers excited by longitudinal discharge with automatic preionization

Pulsed UV lasers (N[2] and XeCl excimer lasers) excited by longitudinal discharge with automatic preionization have been studied. By using spark UV preionization and a charge transfer excitation circuit, the laser performance has been considerably improved. When the laser system was operated as a XeCl excimer laser, laser pulses of about 200 [µ]J output energy, 15 ns width (FWHM) and 1 mrad beam divergence (full angle) were obtained in the compact laser system of 26 cm discharge length at the gas mixture of 1.3 atm (He:Xe:HCl = 1.3 atm:6.0 torr:2.4 torr) and driving voltage of 40 kV. When the laser system was operated as a low pressure N[2] laser (337 nm), laser pulses of about 65 kW peak power and 5 ns width (FMHM) were obtained at the N[2] gas pressure of 60 torr and driving voltage of 40 kV. By using a rectangular cross-section discharge tube instead of a circular cross-section discharge tube, the performance of an N[2] laser has been improved considerably, and laser pulses of about 160 kW peak power, 1.28 mJ output energy and 8 ns pulse width (FWHM) were obtained. The possibilities of the high repetition rate operation have been investigated for N[2] laser and XeCl excimer laser. For N[2] laser, maximum average output power above 100 mW was obtained at the repetition rate of 130 pps.