A simple pulsed CO/sub 2/ laser with long pulse duration of millisecond order

We demonstrate a simple pulsed CO/sub 2/ laser with long pulse duration of millisecond order at low pressure less than 30 Torr. A new power supply for our laser system switches the voltage of AC power line (60 Hz) directly. The power supply doesn't need elements such as a rectified bridge, energy-storage capacitors, and 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 SCR gate is varied from 30/spl deg/ to 150/spl deg/. A ZCS (zero cross switch) circuit and a PIC one-chip microprocessor are used to control the gate signal of SCR precisely. The maximum laser output is 35 W at the total pressure of 18 Torr, the pulse repetition rate of 60 Hz, and SCR gate firing angle of 90/spl deg/. In addition, the obtained laser pulse width is approximately 3 ms (FWHM). It is a relatively long pulse width, compared with any other repetitively pulsed CO/sub 2/ laser.