A simple pulsed CO 2 laser with long milliseconds pulse duration

We demonstrate a simple pulsed CO 2 laser with long pulse duration of millisecond order in a tube at a low pressure of less than 30 Torr. The power supply for our laser system switches the voltage of the ac power line (60 Hz) directly. The power supply does not need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to 60 Hz and the firing angle of the silicon controlled rectifier (SCR) gate is varied from 30° to 150°. The maximum laser output of 35 W is obtained at a total pressure of 18 Torr, a pulse repetition rate of 60 Hz, and a SCR gate firing angle of 90°. In addition, the resulting laser pulse width is approximately 3 ms (full width at half maximum). This is a relatively long pulse width, compared with other repetitively pulsed CO 2 lasers.